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Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]5 <title>The XML C library for Gnome</title>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya 5.1">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]9
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]10<body bgcolor="#ffffff">
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]11<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]12
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]13<h1>Note: this is the flat content of the <a href="index.html">web
14site</a></h1>
15
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]16<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17
18<p></p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]19
20<p>Libxml is the XML C library developped for the Gnome project. XML itself
21is a metalanguage to design markup languages, i.e. text language where
22semantic and structure are added to the content using extra "markup"
23information enclosed between angle bracket. HTML is the most well-known
Daniel Veillard1eb24242002-03-18 11:33:03 +0000[diff] [blame]24markup language. Though the library is written in C <a href="python.html">a
25variety of language binding</a> makes it available in other environments.</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]26
27<p>Libxml2 implements a number of existing standards related to markup
28languages:</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]29<ul>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]30 <li>the XML standard: <a
31 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li>
32 <li>Namespaces in XML: <a
33 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li>
34 <li>XML Base: <a
35 href="http://www.w3.org/TR/xmlbase/">http://www.w3.org/TR/xmlbase/</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]36 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a> :
37 Uniform Resource Identifiers <a
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]38 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li>
39 <li>XML Path Language (XPath) 1.0: <a
40 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li>
41 <li>HTML4 parser: <a
42 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li>
43 <li>most of XML Pointer Language (XPointer) Version 1.0: <a
44 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li>
45 <li>XML Inclusions (XInclude) Version 1.0: <a
46 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li>
47 <li>[ISO-8859-1], <a
48 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8]
49 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a>
50 [UTF-16] core encodings</li>
51 <li>part of SGML Open Technical Resolution TR9401:1997</li>
52 <li>XML Catalogs Working Draft 06 August 2001: <a
53 href="http://www.oasis-open.org/committees/entity/spec-2001-08-06.html">http://www.oasis-open.org/committees/entity/spec-2001-08-06.html</a></li>
Daniel Veillard5c396542002-03-15 07:57:50 +0000[diff] [blame]54 <li>Canonical XML Version 1.0: <a
55 href="http://www.w3.org/TR/xml-c14n">http://www.w3.org/TR/xml-c14n</a>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]56 and the Exclusive XML Canonicalization CR draft <a
57 href="http://www.w3.org/TR/xml-exc-c14n">http://www.w3.org/TR/xml-exc-c14n</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]58</ul>
59
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]60<p>In most cases libxml tries to implement the specifications in a relatively
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]61strict way. As of release 2.4.16, libxml2 passes all 1800+ tests from the <a
62href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests
63Suite</a>.</p>
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]64
65<p>To some extent libxml2 provide some support for the following other
66specification but don't claim to implement them:</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]67<ul>
68 <li>Document Object Model (DOM) <a
69 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
70 it doesn't implement the API itself, gdome2 does this in top of
71 libxml2</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]72 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a> :
73 libxml implements a basic FTP client code</li>
74 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a> :
75 HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]76 <li>SAX: a minimal SAX implementation compatible with early expat
77 versions</li>
78 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
79 XML</li>
80</ul>
81
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]82<p>Libxml2 is known to be very portable, the library should build and work
83without serious troubles on a variety of systems (Linux, Unix, Windows,
84CygWin, MacOs, MacOsX, RISC Os, OS/2, VMS, QNX, MVS, ...)</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]85
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]86<p>Separate documents:</p>
87<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]88 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a> providing an
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]89 implementation of XSLT 1.0 and common extensions like EXSLT for
90 libxml2</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]91 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]92 : a standard DOM2 implementation for libxml2</li>
93 <li><a href="http://www.aleksey.com/xmlsec/">the XMLSec page</a>: an
94 implementation of <a href="http://www.w3.org/TR/xmldsig-core/">W3C XML
95 Digital Signature</a> for libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]96</ul>
97
98<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]99
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]100<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]101href="http://www.w3.org/XML/">XML</a> C library developped for the <a
102href="http://www.gnome.org/">Gnome</a> project. <a
103href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
104structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]105
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]106<p>Here are some key points about libxml:</p>
107<ul>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]108 <li>Libxml exports Push (progressive) and Pull (blocking) type parser
109 interfaces for both XML and HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]110 <li>Libxml can do DTD validation at parse time, using a parsed document
111 instance, or with an arbitrary DTD.</li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]112 <li>Libxml includes complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]113 href="http://www.w3.org/TR/xpath">XPath</a>, <a
114 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
115 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]116 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]117 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]118 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]119 <li>Basic support for HTTP and FTP client allowing aplications to fetch
120 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]121 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]122 <li>The internal document repesentation is as close as possible to the <a
123 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
124 <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]125 like interface</a>; the interface is designed to be compatible with <a
126 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]127 <li>This library is released under the <a
128 href="http://www.opensource.org/licenses/mit-license.html">MIT
129 Licence</a> see the Copyright file in the distribution for the precise
130 wording.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]131</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]132
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]133<p>Warning: unless you are forced to because your application links with a
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]134Gnome-1.X library requiring it, <strong><span
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]135style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
136libxml2</p>
137
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]138<h2><a name="FAQ">FAQ</a></h2>
139
140<p>Table of Content:</p>
141<ul>
142 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
143 <li><a href="FAQ.html#Installati">Installation</a></li>
144 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
145 <li><a href="FAQ.html#Developer">Developer corner</a></li>
146</ul>
147
148<h3><a name="Licence">Licence</a>(s)</h3>
149<ol>
150 <li><em>Licensing Terms for libxml</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]151 <p>libxml is released under the <a
152 href="http://www.opensource.org/licenses/mit-license.html">MIT
153 Licence</a>, see the file Copyright in the distribution for the precise
154 wording</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]155 </li>
156 <li><em>Can I embed libxml in a proprietary application ?</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]157 <p>Yes. The MIT Licence allows you to also keep proprietary the changes
158 you made to libxml, but it would be graceful to provide back bugfixes and
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]159 improvements as patches for possible incorporation in the main
160 development tree</p>
161 </li>
162</ol>
163
164<h3><a name="Installati">Installation</a></h3>
165<ol>
166 <li>Unless you are forced to because your application links with a Gnome
167 library requiring it, <strong><span style="background-color: #FF0000">Do
168 Not Use libxml1</span></strong>, use libxml2</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]169 <li><em>Where can I get libxml</em> ?
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]170 <p>The original distribution comes from <a
171 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
172 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
173 <p>Most linux and Bsd distribution includes libxml, this is probably the
174 safer way for end-users</p>
175 <p>David Doolin provides precompiled Windows versions at <a
176 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
177 </li>
178 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
179 <ul>
180 <li>If you are not concerned by any existing backward compatibility
181 with existing application, install libxml2 only</li>
182 <li>If you are not doing development, you can safely install both.
183 usually the packages <a
184 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
185 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
186 compatible (this is not the case for development packages)</li>
187 <li>If you are a developer and your system provides separate packaging
188 for shared libraries and the development components, it is possible
189 to install libxml and libxml2, and also <a
190 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
191 and <a
192 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
193 too for libxml2 &gt;= 2.3.0</li>
194 <li>If you are developing a new application, please develop against
195 libxml2(-devel)</li>
196 </ul>
197 </li>
198 <li><em>I can't install the libxml package it conflicts with libxml0</em>
199 <p>You probably have an old libxml0 package used to provide the shared
200 library for libxml.so.0, you can probably safely remove it. Anyway the
201 libxml packages provided on <a
202 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
203 libxml.so.0</p>
204 </li>
205 <li><em>I can't install the libxml(2) RPM package due to failed
206 dependancies</em>
207 <p>The most generic solution is to refetch the latest src.rpm , and
208 rebuild it locally with</p>
209 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
210 <p>if everything goes well it will generate two binary rpm (one providing
211 the shared libs and xmllint, and the other one, the -devel package
212 providing includes, static libraries and scripts needed to build
213 applications with libxml(2)) that you can install locally.</p>
214 </li>
215</ol>
216
217<h3><a name="Compilatio">Compilation</a></h3>
218<ol>
219 <li><em>What is the process to compile libxml ?</em>
220 <p>As most UNIX libraries libxml follows the "standard":</p>
221 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
222 <p><code>cd libxml-xxxx</code></p>
223 <p><code>./configure --help</code></p>
224 <p>to see the options, then the compilation/installation proper</p>
225 <p><code>./configure [possible options]</code></p>
226 <p><code>make</code></p>
227 <p><code>make install</code></p>
228 <p>At that point you may have to rerun ldconfig or similar utility to
229 update your list of installed shared libs.</p>
230 </li>
231 <li><em>What other libraries are needed to compile/install libxml ?</em>
232 <p>Libxml does not requires any other library, the normal C ANSI API
233 should be sufficient (please report any violation to this rule you may
234 find).</p>
235 <p>However if found at configuration time libxml will detect and use the
236 following libs:</p>
237 <ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]238 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a
239 highly portable and available widely compression library</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]240 <li>iconv: a powerful character encoding conversion library. It's
241 included by default on recent glibc libraries, so it doesn't need to
242 be installed specifically on linux. It seems it's now <a
243 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
244 of the official UNIX</a> specification. Here is one <a
245 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
246 of the library</a> which source can be found <a
247 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
248 </ul>
249 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]250 <li><em>make check fails on some platforms</em>
251 <p>Sometime the regression tests results don't completely match the value
252 produced by the parser, and the makefile uses diff to print the delta. On
253 some platforms the diff return breaks the compilation process, if the
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]254 diff is small this is probably not a serious problem.</p>
255 <p>Sometimes (especially on Solaris) make checks fails due to limitations
256 in make. Try using GNU-make instead.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]257 </li>
258 <li><em>I use the CVS version and there is no configure script</em>
259 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
260 script to regenerate the configure and Makefiles, like:</p>
261 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
262 </li>
263 <li><em>I have troubles when running make tests with gcc-3.0</em>
264 <p>It seems the initial release of gcc-3.0 has a problem with the
265 optimizer which miscompiles the URI module. Please use another
266 compiler</p>
267 </li>
268</ol>
269
270<h3><a name="Developer">Developer</a> corner</h3>
271<ol>
272 <li><em>xmlDocDump() generates output on one line</em>
273 <p>libxml will not <strong>invent</strong> spaces in the content of a
274 document since <strong>all spaces in the content of a document are
275 significant</strong>. If you build a tree from the API and want
276 indentation:</p>
277 <ol>
278 <li>the correct way is to generate those yourself too</li>
279 <li>the dangerous way is to ask libxml to add those blanks to your
280 content <strong>modifying the content of your document in the
281 process</strong>. The result may not be what you expect. There is
282 <strong>NO</strong> way to guarantee that such a modification won't
283 impact other part of the content of your document. See <a
284 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
285 ()</a> and <a
286 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
287 ()</a></li>
288 </ol>
289 </li>
290 <li>Extra nodes in the document:
291 <p><em>For a XML file as below:</em></p>
292 <pre>&lt;?xml version="1.0"?&gt;
293&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
294&lt;NODE CommFlag="0"/&gt;
295&lt;NODE CommFlag="1"/&gt;
296&lt;/PLAN&gt;</pre>
297 <p><em>after parsing it with the function
298 pxmlDoc=xmlParseFile(...);</em></p>
299 <p><em>I want to the get the content of the first node (node with the
300 CommFlag="0")</em></p>
301 <p><em>so I did it as following;</em></p>
302 <pre>xmlNodePtr pode;
303pnode=pxmlDoc-&gt;children-&gt;children;</pre>
304 <p><em>but it does not work. If I change it to</em></p>
305 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
306 <p><em>then it works. Can someone explain it to me.</em></p>
307 <p></p>
308 <p>In XML all characters in the content of the document are significant
309 <strong>including blanks and formatting line breaks</strong>.</p>
310 <p>The extra nodes you are wondering about are just that, text nodes with
311 the formatting spaces wich are part of the document but that people tend
312 to forget. There is a function <a
313 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
314 ()</a> to remove those at parse time, but that's an heuristic, and its
315 use should be limited to case where you are sure there is no
316 mixed-content in the document.</p>
317 </li>
318 <li><em>I get compilation errors of existing code like when accessing
319 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
320 <p>You are compiling code developed for libxml version 1 and using a
321 libxml2 development environment. Either switch back to libxml v1 devel or
322 even better fix the code to compile with libxml2 (or both) by <a
323 href="upgrade.html">following the instructions</a>.</p>
324 </li>
325 <li><em>I get compilation errors about non existing
326 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
327 fields</em>
328 <p>The source code you are using has been <a
329 href="upgrade.html">upgraded</a> to be able to compile with both libxml
330 and libxml2, but you need to install a more recent version:
331 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
332 </li>
333 <li><em>XPath implementation looks seriously broken</em>
334 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]335 a recent version, there is no known bug in the current version.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]336 </li>
337 <li><em>The example provided in the web page does not compile</em>
338 <p>It's hard to maintain the documentation in sync with the code
339 &lt;grin/&gt; ...</p>
340 <p>Check the previous points 1/ and 2/ raised before, and send
341 patches.</p>
342 </li>
343 <li><em>Where can I get more examples and informations than in the web
344 page</em>
345 <p>Ideally a libxml book would be nice. I have no such plan ... But you
346 can:</p>
347 <ul>
348 <li>check more deeply the <a href="html/libxml-lib.html">existing
349 generated doc</a></li>
350 <li>looks for examples of use for libxml function using the Gnome code
351 for example the following will query the full Gnome CVs base for the
352 use of the <strong>xmlAddChild()</strong> function:
353 <p><a
354 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
355 <p>This may be slow, a large hardware donation to the gnome project
356 could cure this :-)</p>
357 </li>
358 <li><a
359 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]360 the libxml source</a> , I try to write code as clean and documented
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]361 as possible, so looking at it may be helpful. Especially the code of
362 xmllint.c and of the various testXXX.c tests programs should provide
363 good example on how to do things with the library.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]364 </ul>
365 </li>
366 <li>What about C++ ?
367 <p>libxml is written in pure C in order to allow easy reuse on a number
368 of platforms, including embedded systems. I don't intend to convert to
369 C++.</p>
370 <p>There is however a C++ wrapper provided by Ari Johnson
371 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
372 <p>Website: <a
373 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
374 <p>Download: <a
375 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
376 </li>
377 <li>How to validate a document a posteriori ?
378 <p>It is possible to validate documents which had not been validated at
379 initial parsing time or documents who have been built from scratch using
380 the API. Use the <a
381 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
382 function. It is also possible to simply add a Dtd to an existing
383 document:</p>
384 <pre>xmlDocPtr doc; /* your existing document */
385 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
386 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
387
388 doc-&gt;intSubset = dtd;
389 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
390 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
391 </pre>
392 </li>
393 <li>etc ...</li>
394</ol>
395
396<p></p>
397
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]398<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]399
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]400<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]401<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]402 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]403 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]404 documentation</a> automatically extracted from code comments (using <a
405 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
406 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]407 <li>Look at the documentation about <a href="encoding.html">libxml
408 internationalization support</a></li>
Daniel Veillardbc66f852002-01-14 09:49:20 +0000[diff] [blame]409 <li>This page provides a global overview and <a href="example.html">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]410 examples</a> on how to use libxml.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]411 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]412 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
413 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]414 <li>George Lebl wrote <a
415 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]416 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]417 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
418 file</a></li>
419 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
420 starting a new project using libxml you should really use the 2.x
421 version.</li>
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]422 <li>And don't forget to look at the <a
423 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]424</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]425
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]426<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]427
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]428<p>Well, bugs or missing features are always possible, and I will make a
429point of fixing them in a timely fashion. The best way to report a bug is to
430use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
431bug tracking database</a> (make sure to use the "libxml" module name). I look
432at reports there regularly and it's good to have a reminder when a bug is
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]433still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]434
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]435<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]436href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
437href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]438href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
439please visit the <a
440href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
441follow the instructions. <strong>Do not send code, I won't debug it</strong>
442(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]443
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]444<p>Check the following <strong><span style="color: #FF0000">before
445posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]446<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]447 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]448 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
449 version</a>, and that the problem still shows up in those</li>
450 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
451 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]452 there is probably a fix available, similary check the <a
453 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]454 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]455 <li>make sure you can reproduce the bug with xmllint or one of the test
456 programs found in source in the distribution</li>
457 <li>Please send the command showing the error as well as the input (as an
458 attachement)</li>
459</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]460
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]461<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]462href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]463related I will approve it.. Please do not send me mail directly, it makes
464things really harder to track and in some cases I'm not the best person to
465answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]466
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]467<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]468probably be processed faster.</p>
469
470<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]471href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]472provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]473questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]474documentantion</a> is not as polished as I would like (i need to learn more
475about Docbook), but it's a good starting point.</p>
476
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]477<h2><a name="help">How to help</a></h2>
478
479<p>You can help the project in various ways, the best thing to do first is to
480subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]481href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
482href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]483database:</a>:</p>
484<ol>
485 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]486 <li>provide the diffs when you port libxml to a new platform. They may not
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]487 be integrated in all cases but help pinpointing portability problems
488 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]489 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]490 as HTML diffs).</li>
491 <li>provide new documentations pieces (translations, examples, etc ...)</li>
492 <li>Check the TODO file and try to close one of the items</li>
493 <li>take one of the points raised in the archive or the bug database and
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]494 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
495 </a>before to avoid synchronization problems and check that the suggested
496 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]497</ol>
498
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]499<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]500
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]501<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]502href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
503href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
504href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]505href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]506as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]507archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]508href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
509packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]510href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
511href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]512packages installed to compile applications using libxml.) <a
513href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
514of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]515href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]516provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]517Pennington</a> provides <a href="http://garypennington.net/libxml2/">Solaris
518binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]519
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]520<p><a name="Snapshot">Snapshot:</a></p>
521<ul>
522 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]523 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]524 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]525 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]526</ul>
527
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]528<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]529
530<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]531platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]532languages have been provided, and can be found in the <a
533href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]534
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]535<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]536<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]537 <li><p>The <a
538 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]539 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]540 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
541 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]542 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]543 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]544</ul>
545
546<h2><a name="News">News</a></h2>
547
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]548<h3>CVS only : check the <a
549href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]550for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]551
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]552<p>Items floating around but not actively worked on, get in touch with me if
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]553you want to test those</p>
554<ul>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]555 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
556 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]557</ul>
558
Daniel Veillard19274092002-03-25 16:48:03 +0000[diff] [blame^]559<h3>2.4.19: Mar 25 2002</h3>
560<ul>
561 <li>bug fixes: half a dozen XPath bugs, Validation, ISO-Latin to UTF8
562 encoder</li>
563 <li>portability fixes in the HTTP code</li>
564 <li>memory allocation checks using valgrind, and profiling tests </li>
565 <li>revamp of the Windows build and Makefiles</li>
566</ul>
567
Daniel Veillard34ce8be2002-03-18 19:37:11 +0000[diff] [blame]568<h3>2.4.18: Mar 18 2002</h3>
569<ul>
570 <li>bug fixes: tree, SAX, canonicalization, validation, portability,
571 xpath</li>
572 <li>removed the --with-buffer option it was becoming unmaintainable</li>
573 <li>serious cleanup of the Python makefiles</li>
574 <li>speedup patch to XPath very effective for DocBook stylesheets</li>
575 <li>Fixes for Windows build, cleanup of the documentation</li>
576</ul>
577
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]578<h3>2.4.17: Mar 8 2002</h3>
579<ul>
580 <li>a lot of bug fixes, including "namespace nodes have no parents in
581 XPath"</li>
582 <li>fixed/improved the Python wrappers, added more examples and more
583 regression tests, XPath extension functions can now return node-sets</li>
584 <li>added the XML Canonalization support from Aleksey Sanin</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]585</ul>
586
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]587<h3>2.4.16: Feb 20 2002</h3>
588<ul>
589 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite
590 from OASIS and W3C. Compliance has been significantly improved.</li>
591 <li>a couple of portability fixes too.</li>
592</ul>
593
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]594<h3>2.4.15: Feb 11 2002</h3>
595<ul>
596 <li>Fixed the Makefiles, especially the python module ones</li>
597 <li>A few bug fixes and cleanup</li>
598 <li>Includes cleanup</li>
599</ul>
600
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]601<h3>2.4.14: Feb 8 2002</h3>
602<ul>
603 <li>Change of Licence to the <a
604 href="http://www.opensource.org/licenses/mit-license.html">MIT
605 Licence</a> basisally for integration in XFree86 codebase, and removing
606 confusion around the previous dual-licencing</li>
607 <li>added Python bindings, beta software but should already be quite
608 complete</li>
609 <li>a large number of fixes and cleanups, especially for all tree
610 manipulations</li>
611 <li>cleanup of the headers, generation of a reference API definition in
612 XML</li>
613</ul>
614
615<h3>2.4.13: Jan 14 2002</h3>
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]616<ul>
617 <li>update of the documentation: John Fleck and Charlie Bozeman</li>
618 <li>cleanup of timing code from Justin Fletcher</li>
619 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei
620 Narojnyi</li>
621 <li>Cygwin patch from Robert Collins</li>
622 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li>
623</ul>
624
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]625<h3>2.4.12: Dec 7 2001</h3>
626<ul>
627 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman),
628 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups
629 (robert)</li>
630 <li>Eric Lavigne contributed project files for MacOS</li>
631 <li>some makefiles cleanups</li>
632</ul>
633
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]634<h3>2.4.11: Nov 26 2001</h3>
635<ul>
636 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
637 cleanups</li>
638 <li>xmllint man pages improvement by Heiko Rupp</li>
639 <li>updated VMS build instructions from John A Fotheringham</li>
640 <li>Windows Makefiles updates from Igor</li>
641</ul>
642
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]643<h3>2.4.10: Nov 10 2001</h3>
644<ul>
645 <li>URI escaping fix (Joel Young)</li>
646 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
647 <li>Fixes namespace handling problems when using DTD and validation</li>
648 <li>improvements on xmllint: Morus Walter patches for --format and
649 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
650 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
651 <li>fixes to the HTML parser</li>
652</ul>
653
654<h3>2.4.9: Nov 6 2001</h3>
655<ul>
656 <li>fixes more catalog bugs</li>
657 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
658</ul>
659
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]660<h3>2.4.8: Nov 4 2001</h3>
661<ul>
662 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
663 tool</li>
664 <li>fixed a compile errors and some includes troubles.</li>
665</ul>
666
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]667<h3>2.4.7: Oct 30 2001</h3>
668<ul>
669 <li>exported some debugging interfaces</li>
670 <li>serious rewrite of the catalog code</li>
671 <li>integrated Gary Pennington thread safety patch, added configure option
672 and regression tests</li>
673 <li>removed an HTML parser bug</li>
674 <li>fixed a couple of potentially serious validation bugs</li>
675 <li>integrated the SGML DocBook support in xmllint</li>
676 <li>changed the nanoftp anonymous login passwd</li>
677 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
678 <li>general bug fixes</li>
679 <li>updated xmllint man page by John Fleck</li>
680 <li>some VMS and Windows updates</li>
681</ul>
682
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]683<h3>2.4.6: Oct 10 2001</h3>
684<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]685 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]686 <li>portability and configure fixes</li>
687 <li>an infinite loop on the HTML parser was removed (William)</li>
688 <li>Windows makefile patches from Igor</li>
689 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
690 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
691</ul>
692
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]693<h3>2.4.5: Sep 14 2001</h3>
694<ul>
695 <li>Remove a few annoying bugs in 2.4.4</li>
696 <li>forces the HTML serializer to output decimal charrefs since some
697 version of Netscape can't handle hexadecimal ones</li>
698</ul>
699
700<h3>1.8.16: Sep 14 2001</h3>
701<ul>
702 <li>maintenance release of the old libxml1 branch, couple of bug and
703 portability fixes</li>
704</ul>
705
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]706<h3>2.4.4: Sep 12 2001</h3>
707<ul>
708 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
709 Catalog</li>
710 <li>a few bug fixes and some portability changes</li>
711 <li>some documentation cleanups</li>
712</ul>
713
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]714<h3>2.4.3: Aug 23 2001</h3>
715<ul>
716 <li>XML Catalog support see the doc</li>
717 <li>New NaN/Infinity floating point code</li>
718 <li>A few bug fixes</li>
719</ul>
720
721<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]722<ul>
723 <li>adds xmlLineNumbersDefault() to control line number generation</li>
724 <li>lot of bug fixes</li>
725 <li>the Microsoft MSC projects files shuld now be up to date</li>
726 <li>inheritance of namespaces from DTD defaulted attributes</li>
727 <li>fixes a serious potential security bug</li>
728 <li>added a --format option to xmllint</li>
729</ul>
730
731<h3>2.4.1: July 24 2001</h3>
732<ul>
733 <li>possibility to keep line numbers in the tree</li>
734 <li>some computation NaN fixes</li>
735 <li>extension of the XPath API</li>
736 <li>cleanup for alpha and ia64 targets</li>
737 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]738</ul>
739
740<h3>2.4.0: July 10 2001</h3>
741<ul>
742 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
743 <li>Fixed XML Base implementation, added a coupel of examples to the
744 regression tests</li>
745 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]746</ul>
747
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]748<h3>2.3.14: July 5 2001</h3>
749<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]750 <li>fixed some entities problems and reduce mem requirement when
751 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]752 <li>lots of improvements in the XPath queries interpreter can be
753 substancially faster</li>
754 <li>Makefiles and configure cleanups</li>
755 <li>Fixes to XPath variable eval, and compare on empty node set</li>
756 <li>HTML tag closing bug fixed</li>
757 <li>Fixed an URI reference computating problem when validating</li>
758</ul>
759
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]760<h3>2.3.13: June 28 2001</h3>
761<ul>
762 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
763 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
764</ul>
765
766<h3>1.8.14: June 28 2001</h3>
767<ul>
768 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
769 <li>Small Makefile fix</li>
770</ul>
771
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]772<h3>2.3.12: June 26 2001</h3>
773<ul>
774 <li>lots of cleanup</li>
775 <li>a couple of validation fix</li>
776 <li>fixed line number counting</li>
777 <li>fixed serious problems in the XInclude processing</li>
778 <li>added support for UTF8 BOM at beginning of entities</li>
779 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
780 miscompile uri.c (William), Thomas Leitner provided a fix for the
781 optimizer on Tru64</li>
782 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
783 compilation on Windows MSC</li>
784 <li>update of libxml-doc.el (Felix Natter)</li>
785 <li>fixed 2 bugs in URI normalization code</li>
786</ul>
787
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]788<h3>2.3.11: June 17 2001</h3>
789<ul>
790 <li>updates to trio, Makefiles and configure should fix some portability
791 problems (alpha)</li>
792 <li>fixed some HTML serialization problems (pre, script, and block/inline
793 handling), added encoding aware APIs, cleanup of this code</li>
794 <li>added xmlHasNsProp()</li>
795 <li>implemented a specific PI for encoding support in the DocBook SGML
796 parser</li>
797 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
798 node selection)</li>
799 <li>fixed a performance problem and an error in the validation code</li>
800 <li>fixed XInclude routine to implement the recursive behaviour</li>
801 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
802 <li>added --version to xmllint for bug reports</li>
803</ul>
804
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]805<h3>2.3.10: June 1 2001</h3>
806<ul>
807 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]808 <li>a number of reported bugs got fixed, in XPath, iconv detection,
809 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]810 <li>XPath string function should now handle unicode correctly</li>
811</ul>
812
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]813<h3>2.3.9: May 19 2001</h3>
814
815<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
816<ul>
817 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
818 <li>some serious speed optimisation again</li>
819 <li>some documentation cleanups</li>
820 <li>trying to get better linking on solaris (-R)</li>
821 <li>XPath API cleanup from Thomas Broyer</li>
822 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
823 xmlValidGetValidElements()</li>
824 <li>Added an INSTALL file</li>
825 <li>Attribute removal added to API: #54433</li>
826 <li>added a basic support for SGML catalogs</li>
827 <li>fixed xmlKeepBlanksDefault(0) API</li>
828 <li>bugfix in xmlNodeGetLang()</li>
829 <li>fixed a small configure portability problem</li>
830 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
831</ul>
832
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]833<h3>1.8.13: May 14 2001</h3>
834<ul>
835 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
836</ul>
837
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]838<h3>2.3.8: May 3 2001</h3>
839<ul>
840 <li>Integrated an SGML DocBook parser for the Gnome project</li>
841 <li>Fixed a few things in the HTML parser</li>
842 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
843 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]844 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
845 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]846 <li>incorporated more Windows cleanup</li>
847 <li>added xmlSaveFormatFile()</li>
848 <li>fixed problems in copying nodes with entities references (gdome)</li>
849 <li>removed some troubles surrounding the new validation module</li>
850</ul>
851
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]852<h3>2.3.7: April 22 2001</h3>
853<ul>
854 <li>lots of small bug fixes, corrected XPointer</li>
855 <li>Non determinist content model validation support</li>
856 <li>added xmlDocCopyNode for gdome2</li>
857 <li>revamped the way the HTML parser handles end of tags</li>
858 <li>XPath: corrctions of namespacessupport and number formatting</li>
859 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
860 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
861 <li>Improved validation speed sensible for DocBook</li>
862 <li>fixed a big bug with ID declared in external parsed entities</li>
863 <li>portability fixes, update of Trio from Bjorn Reese</li>
864</ul>
865
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]866<h3>2.3.6: April 8 2001</h3>
867<ul>
868 <li>Code cleanup using extreme gcc compiler warning options, found and
869 cleared half a dozen potential problem</li>
870 <li>the Eazel team found an XML parser bug</li>
871 <li>cleaned up the user of some of the string formatting function. used the
872 trio library code to provide the one needed when the platform is missing
873 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]874 <li>xpath: removed a memory leak and fixed the predicate evaluation
875 problem, extended the testsuite and cleaned up the result. XPointer seems
876 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]877</ul>
878
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]879<h3>2.3.5: Mar 23 2001</h3>
880<ul>
881 <li>Biggest change is separate parsing and evaluation of XPath expressions,
882 there is some new APIs for this too</li>
883 <li>included a number of bug fixes(XML push parser, 51876, notations,
884 52299)</li>
885 <li>Fixed some portability issues</li>
886</ul>
887
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]888<h3>2.3.4: Mar 10 2001</h3>
889<ul>
890 <li>Fixed bugs #51860 and #51861</li>
891 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
892 size to be application tunable.</li>
893 <li>Some cleanup in the validation code, still a bug left and this part
894 should probably be rewritten to support ambiguous content model :-\</li>
895 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
896 parser</li>
897 <li>Fixed another bug in xmlNodeGetContent()</li>
898 <li>Bjorn fixed XPath node collection and Number formatting</li>
899 <li>Fixed a loop reported in the HTML parsing</li>
900 <li>blank space are reported even if the Dtd content model proves that they
901 are formatting spaces, this is for XmL conformance</li>
902</ul>
903
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]904<h3>2.3.3: Mar 1 2001</h3>
905<ul>
906 <li>small change in XPath for XSLT</li>
907 <li>documentation cleanups</li>
908 <li>fix in validation by Gary Pennington</li>
909 <li>serious parsing performances improvements</li>
910</ul>
911
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]912<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]913<ul>
914 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
915 <li>fixed a Dtd parsing bug</li>
916 <li>fixed a bug in xmlNodeGetContent</li>
917 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
918</ul>
919
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]920<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]921<ul>
922 <li>some XPath and HTML bug fixes for XSLT</li>
923 <li>small extension of the hash table interfaces for DOM gdome2
924 implementation</li>
925 <li>A few bug fixes</li>
926</ul>
927
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]928<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]929<ul>
930 <li>Lots of XPath bug fixes</li>
931 <li>Add a mode with Dtd lookup but without validation error reporting for
932 XSLT</li>
933 <li>Add support for text node without escaping (XSLT)</li>
934 <li>bug fixes for xmlCheckFilename</li>
935 <li>validation code bug fixes from Gary Pennington</li>
936 <li>Patch from Paul D. Smith correcting URI path normalization</li>
937 <li>Patch to allow simultaneous install of libxml-devel and
938 libxml2-devel</li>
939 <li>the example Makefile is now fixed</li>
940 <li>added HTML to the RPM packages</li>
941 <li>tree copying bugfixes</li>
942 <li>updates to Windows makefiles</li>
943 <li>optimisation patch from Bjorn Reese</li>
944</ul>
945
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]946<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]947<ul>
948 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
949 <li>added htmlHandleOmittedElem()</li>
950 <li>Applied Bjorn Reese's IPV6 first patch</li>
951 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]952 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]953</ul>
954
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]955<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]956<ul>
957 <li>Fix the Windows problems of 2.2.8</li>
958 <li>integrate OpenVMS patches</li>
959 <li>better handling of some nasty HTML input</li>
960 <li>Improved the XPointer implementation</li>
961 <li>integrate a number of provided patches</li>
962</ul>
963
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]964<h3>2.2.9: Nov 25 2000</h3>
965<ul>
966 <li>erroneous release :-(</li>
967</ul>
968
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]969<h3>2.2.8: Nov 13 2000</h3>
970<ul>
971 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
972 support</li>
973 <li>Patch in conditional section handling</li>
974 <li>updated MS compiler project</li>
975 <li>fixed some XPath problems</li>
976 <li>added an URI escaping function</li>
977 <li>some other bug fixes</li>
978</ul>
979
980<h3>2.2.7: Oct 31 2000</h3>
981<ul>
982 <li>added message redirection</li>
983 <li>XPath improvements (thanks TOM !)</li>
984 <li>xmlIOParseDTD() added</li>
985 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
986 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
987</ul>
988
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]989<h3>2.2.6: Oct 25 2000:</h3>
990<ul>
991 <li>Added an hash table module, migrated a number of internal structure to
992 those</li>
993 <li>Fixed a posteriori validation problems</li>
994 <li>HTTP module cleanups</li>
995 <li>HTML parser improvements (tag errors, script/style handling, attribute
996 normalization)</li>
997 <li>coalescing of adjacent text nodes</li>
998 <li>couple of XPath bug fixes, exported the internal API</li>
999</ul>
1000
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]1001<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1002<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]1003 <li>XPointer implementation and testsuite</li>
1004 <li>Lot of XPath fixes, added variable and functions registration, more
1005 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1006 <li>Portability fixes, lots of enhancements toward an easy Windows build
1007 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]1008 <li>Late validation fixes</li>
1009 <li>Integrated a lot of contributed patches</li>
1010 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]1011 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]1012</ul>
1013
1014<h3>2.2.4: Oct 1 2000:</h3>
1015<ul>
1016 <li>main XPath problem fixed</li>
1017 <li>Integrated portability patches for Windows</li>
1018 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1019</ul>
1020
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1021<h3>2.2.3: Sep 17 2000</h3>
1022<ul>
1023 <li>bug fixes</li>
1024 <li>cleanup of entity handling code</li>
1025 <li>overall review of all loops in the parsers, all sprintf usage has been
1026 checked too</li>
1027 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
1028 works smoothly now.</li>
1029</ul>
1030
1031<h3>1.8.10: Sep 6 2000</h3>
1032<ul>
1033 <li>bug fix release for some Gnome projects</li>
1034</ul>
1035
1036<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1037<ul>
1038 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]1039 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1040</ul>
1041
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1042<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1043<ul>
1044 <li>a purely bug fixes release</li>
1045 <li>fixed an encoding support problem when parsing from a memory block</li>
1046 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1047 <li>removed a bug in the function allowing to override the memory
1048 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1049</ul>
1050
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1051<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]1052<ul>
1053 <li>applied a lot of portability fixes</li>
1054 <li>better encoding support/cleanup and saving (content is now always
1055 encoded in UTF-8)</li>
1056 <li>the HTML parser now correctly handles encodings</li>
1057 <li>added xmlHasProp()</li>
1058 <li>fixed a serious problem with &amp;#38;</li>
1059 <li>propagated the fix to FTP client</li>
1060 <li>cleanup, bugfixes, etc ...</li>
1061 <li>Added a page about <a href="encoding.html">libxml Internationalization
1062 support</a></li>
1063</ul>
1064
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1065<h3>1.8.9: July 9 2000</h3>
1066<ul>
1067 <li>fixed the spec the RPMs should be better</li>
1068 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
1069 rpmfind users problem</li>
1070</ul>
1071
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]1072<h3>2.1.1: July 1 2000</h3>
1073<ul>
1074 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1075 <li>improvements on the HTML parser</li>
1076</ul>
1077
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1078<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1079<ul>
1080 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1081 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1082 about &amp;#38; charref parsing</li>
1083 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1084 also contains numerous fixes and enhancements:
1085 <ul>
1086 <li>added xmlStopParser() to stop parsing</li>
1087 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1088 <li>includes XPath patches provided by Picdar Technology</li>
1089 <li>tried to fix as much as possible DtD validation and namespace
1090 related problems</li>
1091 <li>output to a given encoding has been added/tested</li>
1092 <li>lot of various fixes</li>
1093 </ul>
1094 </li>
1095</ul>
1096
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1097<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1098<ul>
1099 <li>First public release of libxml2. If you are using libxml, it's a good
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1100 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1101 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1102 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1103 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1104 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1105 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1106 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1107 <pre>#include "xxx.h"</pre>
1108 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1109 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1110 <li>the memory allocation routines used by libxml can now be overloaded
1111 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1112 <li>The previously CVS only tool tester has been renamed
1113 <strong>xmllint</strong> and is now installed as part of the libxml2
1114 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1115 <li>The I/O interface has been revamped. There is now ways to plug in
1116 specific I/O modules, either at the URI scheme detection level using
1117 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1118 parser context using xmlCreateIOParserCtxt()</li>
1119 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1120 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1121 <li>a number of optional features of libxml can now be excluded at
1122 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1123</ul>
1124
1125<h3>2.0.0beta: Mar 14 2000</h3>
1126<ul>
1127 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1128 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1129 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1130 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1131 <li>This version is now the head in the Gnome CVS base, the old one is
1132 available under the tag LIB_XML_1_X</li>
1133 <li>This includes a very large set of changes. Froma programmatic point of
1134 view applications should not have to be modified too much, check the <a
1135 href="upgrade.html">upgrade page</a></li>
1136 <li>Some interfaces may changes (especially a bit about encoding).</li>
1137 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1138 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1139 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1140 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1141 <li>Better handling of entities, especially well formedness checking
1142 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1143 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1144 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1145 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1146 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1147 </ul>
1148 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1149 <li>Serious progress were made toward compliance, <a
1150 href="conf/result.html">here are the result of the test</a> against the
1151 OASIS testsuite (except the japanese tests since I don't support that
1152 encoding yet). This URL is rebuilt every couple of hours using the CVS
1153 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1154</ul>
1155
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1156<h3>1.8.7: Mar 6 2000</h3>
1157<ul>
1158 <li>This is a bug fix release:</li>
1159 <li>It is possible to disable the ignorable blanks heuristic used by
1160 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1161 that for adherence to XML spec, this behaviour will be disabled by
1162 default in 2.x . The same function will allow to keep compatibility for
1163 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1164 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1165 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1166 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1167 compilation on some platforms has been fixed</li>
1168 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1169 URIs</li>
1170</ul>
1171
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1172<h3>1.8.6: Jan 31 2000</h3>
1173<ul>
1174 <li>added a nanoFTP transport module, debugged until the new version of <a
1175 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1176 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1177</ul>
1178
1179<h3>1.8.5: Jan 21 2000</h3>
1180<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1181 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1182 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1183 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1184 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1185 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1186 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1187 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1188 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1189</ul>
1190
1191<h3>1.8.4: Jan 13 2000</h3>
1192<ul>
1193 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1194 <li>all exit() call should have been removed from libxml</li>
1195 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1196 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1197</ul>
1198
1199<h3>1.8.3: Jan 5 2000</h3>
1200<ul>
1201 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1202 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1203 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1204 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1205 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1206 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1207 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1208 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1209 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1210</ul>
1211
1212<h3>1.8.2: Dec 21 1999</h3>
1213<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1214 <li>I got another problem with includes and C++, I hope this issue is fixed
1215 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1216 <li>Added a few tree modification functions: xmlReplaceNode,
1217 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1218 xmlDocSetRootElement</li>
1219 <li>Tried to improve the HTML output with help from <a
1220 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1221</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1222
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1223<h3>1.8.1: Dec 18 1999</h3>
1224<ul>
1225 <li>various patches to avoid troubles when using libxml with C++ compilers
1226 the "namespace" keyword and C escaping in include files</li>
1227 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1228 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1229 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1230 <li>fixed a posteriori validation (validation after parsing, or by using a
1231 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1232 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1233</ul>
1234
1235<h3>1.8.0: Dec 12 1999</h3>
1236<ul>
1237 <li>cleanup, especially memory wise</li>
1238 <li>the parser should be more reliable, especially the HTML one, it should
1239 not crash, whatever the input !</li>
1240 <li>Integrated various patches, especially a speedup improvement for large
1241 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1242 configure with --with-buffers to enable them.</li>
1243 <li>attribute normalization, oops should have been added long ago !</li>
1244 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1245 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1246</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1247
1248<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1249<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1250 <li>Lots of HTML improvement</li>
1251 <li>Fixed some errors when saving both XML and HTML</li>
1252 <li>More examples, the regression tests should now look clean</li>
1253 <li>Fixed a bug with contiguous charref</li>
1254</ul>
1255
1256<h3>1.7.3: Sep 29 1999</h3>
1257<ul>
1258 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1259 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1260 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1261</ul>
1262
1263<h3>1.7.1: Sep 24 1999</h3>
1264<ul>
1265 <li>The basic type for strings manipulated by libxml has been renamed in
1266 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1267 is that CHAR was conflicting with a predefined type on Windows. However
1268 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1269 <strong>#define </strong>.</li>
1270 <li>Changed another error : the use of a structure field called errno, and
1271 leading to troubles on platforms where it's a macro</li>
1272</ul>
1273
1274<h3>1.7.0: sep 23 1999</h3>
1275<ul>
1276 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1277 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1278 <li>Added an errno to report errors by another mean than a simple printf
1279 like callback</li>
1280 <li>Finished ID/IDREF support and checking when validation</li>
1281 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1282 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1283 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1284 implementation</li>
1285 <li>Added an HTML parser front-end</li>
1286</ul>
1287
1288<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1289
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1290<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1291markup-based structured documents. Here is <a name="example">an example XML
1292document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1293<pre>&lt;?xml version="1.0"?&gt;
1294&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1295 &lt;head&gt;
1296 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1297 &lt;/head&gt;
1298 &lt;chapter&gt;
1299 &lt;title&gt;The Linux adventure&lt;/title&gt;
1300 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1301 &lt;image href="linus.gif"/&gt;
1302 &lt;p&gt;...&lt;/p&gt;
1303 &lt;/chapter&gt;
1304&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1305
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1306<p>The first line specifies that it's an XML document and gives useful
1307information about its encoding. Then the document is a text format whose
1308structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1309to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1310(no content), a single tag can serve as both the opening and closing tag if
1311it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1312that, for example, the image tag has no content (just an attribute) and is
1313closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1314
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1315<p>XML can be applied sucessfully to a wide range of uses, from long term
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1316structured document maintenance (where it follows the steps of SGML) to
1317simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1318spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1319it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1320
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1321<h2><a name="XSLT">XSLT</a></h2>
1322
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1323<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1324
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1325<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1326language for transforming XML documents into other XML documents (or
1327HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1328
1329<p>A separate library called libxslt is being built on top of libxml2. This
1330module "libxslt" can be found in the Gnome CVS base too.</p>
1331
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1332<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1333href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1334supported and the progresses on the <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1335href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog"
1336name="Changelog">Changelog</a></p>
1337
1338<h2><a name="Python">Python and bindings</a></h2>
1339
1340<p>There is a number of language bindings and wrappers available for libxml2,
1341the list below is not exhaustive. Please contact the <a
1342href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
1343(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
1344order to get updates to this list or to discuss the specific topic of libxml2
1345or libxslt wrappers or bindings:</p>
1346<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1347 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
1348 for libxml:<br>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1349 Website: <a
1350 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
1351 Download: <a
1352 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
1353 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
1354 based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
1355 <li><a
1356 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1357 Sergeant</a> developped <a
1358 href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
1359 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
1360 application server</a></li>
1361 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
1362 earlier version of the libxml/libxslt <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1363 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
1364 <li>Petr Kozelka provides <a
1365 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
1366 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
1367 <li>Wai-Sun "Squidster" Chia provides <a
1368 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
1369 libxml2 bindings are also available in Ruby through the <a
1370 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
1371 maintained by Tobias Peters.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1372 <li>Steve Ball and contributors maintains <a
1373 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
1374 Tcl</a></li>
1375 <li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1376</ul>
1377
1378<p>The distribution includes a set of Python bindings, which are garanteed to
1379be maintained as part of the library in the future, though the Python
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]1380interface have not yet reached the maturity of the C API.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1381
1382<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]1383<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1384 <li>If you use an RPM based distribution, simply install the <a
1385 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python
1386 RPM</a> (and if needed the <a
1387 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
1388 RPM</a>).</li>
1389 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
1390 module distribution</a> corresponding to your installed version of
1391 libxml2 and libxslt. Note that to install it you will need both libxml2
1392 and libxslt installed and run "python setup.py build install" in the
1393 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]1394</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1395
1396<p>The distribution includes a set of examples and regression tests for the
1397python bindings in the <code>python/tests</code> directory. Here are some
1398excepts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1399
1400<h3>tst.py:</h3>
1401
1402<p>This is a basic test of the file interface and DOM navigation:</p>
1403<pre>import libxml2
1404
1405doc = libxml2.parseFile("tst.xml")
1406if doc.name != "tst.xml":
1407 print "doc.name failed"
1408 sys.exit(1)
1409root = doc.children
1410if root.name != "doc":
1411 print "root.name failed"
1412 sys.exit(1)
1413child = root.children
1414if child.name != "foo":
1415 print "child.name failed"
1416 sys.exit(1)
1417doc.freeDoc()</pre>
1418
1419<p>The Python module is called libxml2, parseFile is the equivalent of
1420xmlParseFile (most of the bindings are automatically generated, and the xml
1421prefix is removed and the casing convention are kept). All node seen at the
1422binding level share the same subset of accesors:</p>
1423<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1424 <li><code>name</code> : returns the node name</li>
1425 <li><code>type</code> : returns a string indicating the node
1426 typ<code>e</code></li>
1427 <li><code>content</code> : returns the content of the node, it is based on
1428 xmlNodeGetContent() and hence is recursive.</li>
1429 <li><code>parent</code> , <code>children</code>, <code>last</code>,
1430 <code>next</code>, <code>prev</code>, <code>doc</code>,
1431 <code>properties</code>: pointing to the associated element in the tree,
1432 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1433</ul>
1434
1435<p>Also note the need to explicitely deallocate documents with freeDoc() .
1436Reference counting for libxml2 trees would need quite a lot of work to
1437function properly, and rather than risk memory leaks if not implemented
1438correctly it sounds safer to have an explicit function to free a tree. The
1439wrapper python objects like doc, root or child are them automatically garbage
1440collected.</p>
1441
1442<h3>validate.py:</h3>
1443
1444<p>This test check the validation interfaces and redirection of error
1445messages:</p>
1446<pre>import libxml2
1447
1448#desactivate error messages from the validation
1449def noerr(ctx, str):
1450 pass
1451
1452libxml2.registerErrorHandler(noerr, None)
1453
1454ctxt = libxml2.createFileParserCtxt("invalid.xml")
1455ctxt.validate(1)
1456ctxt.parseDocument()
1457doc = ctxt.doc()
1458valid = ctxt.isValid()
1459doc.freeDoc()
1460if valid != 0:
1461 print "validity chec failed"</pre>
1462
1463<p>The first thing to notice is the call to registerErrorHandler(), it
1464defines a new error handler global to the library. It is used to avoid seeing
1465the error messages when trying to validate the invalid document.</p>
1466
1467<p>The main interest of that test is the creation of a parser context with
1468createFileParserCtxt() and how the behaviour can be changed before calling
1469parseDocument() . Similary the informations resulting from the parsing phase
1470are also available using context methods.</p>
1471
1472<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
1473C function interfaces in terms of objects method as much as possible. The
1474best to get a complete view of what methods are supported is to look at the
1475libxml2.py module containing all the wrappers.</p>
1476
1477<h3>push.py:</h3>
1478
1479<p>This test show how to activate the push parser interface:</p>
1480<pre>import libxml2
1481
1482ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
1483ctxt.parseChunk("/&gt;", 2, 1)
1484doc = ctxt.doc()
1485
1486doc.freeDoc()</pre>
1487
1488<p>The context is created with a speciall call based on the
1489xmlCreatePushParser() from the C library. The first argument is an optional
1490SAX callback object, then the initial set of data, the lenght and the name of
1491the resource in case URI-References need to be computed by the parser.</p>
1492
1493<p>Then the data are pushed using the parseChunk() method, the last call
1494setting the thrird argument terminate to 1.</p>
1495
1496<h3>pushSAX.py:</h3>
1497
1498<p>this test show the use of the event based parsing interfaces. In this case
1499the parser does not build a document, but provides callback information as
1500the parser makes progresses analyzing the data being provided:</p>
1501<pre>import libxml2
1502log = ""
1503
1504class callback:
1505 def startDocument(self):
1506 global log
1507 log = log + "startDocument:"
1508
1509 def endDocument(self):
1510 global log
1511 log = log + "endDocument:"
1512
1513 def startElement(self, tag, attrs):
1514 global log
1515 log = log + "startElement %s %s:" % (tag, attrs)
1516
1517 def endElement(self, tag):
1518 global log
1519 log = log + "endElement %s:" % (tag)
1520
1521 def characters(self, data):
1522 global log
1523 log = log + "characters: %s:" % (data)
1524
1525 def warning(self, msg):
1526 global log
1527 log = log + "warning: %s:" % (msg)
1528
1529 def error(self, msg):
1530 global log
1531 log = log + "error: %s:" % (msg)
1532
1533 def fatalError(self, msg):
1534 global log
1535 log = log + "fatalError: %s:" % (msg)
1536
1537handler = callback()
1538
1539ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
1540chunk = " url='tst'&gt;b"
1541ctxt.parseChunk(chunk, len(chunk), 0)
1542chunk = "ar&lt;/foo&gt;"
1543ctxt.parseChunk(chunk, len(chunk), 1)
1544
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame]1545reference = "startDocument:startElement foo {'url': 'tst'}:" + \
1546 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1547if log != reference:
1548 print "Error got: %s" % log
1549 print "Exprected: %s" % reference</pre>
1550
1551<p>The key object in that test is the handler, it provides a number of entry
1552points which can be called by the parser as it makes progresses to indicate
1553the information set obtained. The full set of callback is larger than what
1554the callback class in that specific example implements (see the SAX
1555definition for a complete list). The wrapper will only call those supplied by
1556the object when activated. The startElement receives the names of the element
1557and a dictionnary containing the attributes carried by this element.</p>
1558
1559<p>Also note that the reference string generated from the callback shows a
1560single character call even though the string "bar" is passed to the parser
1561from 2 different call to parseChunk()</p>
1562
1563<h3>xpath.py:</h3>
1564
1565<p>This is a basic test of XPath warppers support</p>
1566<pre>import libxml2
1567
1568doc = libxml2.parseFile("tst.xml")
1569ctxt = doc.xpathNewContext()
1570res = ctxt.xpathEval("//*")
1571if len(res) != 2:
1572 print "xpath query: wrong node set size"
1573 sys.exit(1)
1574if res[0].name != "doc" or res[1].name != "foo":
1575 print "xpath query: wrong node set value"
1576 sys.exit(1)
1577doc.freeDoc()
1578ctxt.xpathFreeContext()</pre>
1579
1580<p>This test parses a file, then create an XPath context to evaluate XPath
1581expression on it. The xpathEval() method execute an XPath query and returns
1582the result mapped in a Python way. String and numbers are natively converted,
1583and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
1584the document, the XPath context need to be freed explicitely, also not that
1585the result of the XPath query may point back to the document tree and hence
1586the document must be freed after the result of the query is used.</p>
1587
1588<h3>xpathext.py:</h3>
1589
1590<p>This test shows how to extend the XPath engine with functions written in
1591python:</p>
1592<pre>import libxml2
1593
1594def foo(ctx, x):
1595 return x + 1
1596
1597doc = libxml2.parseFile("tst.xml")
1598ctxt = doc.xpathNewContext()
1599libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
1600res = ctxt.xpathEval("foo(1)")
1601if res != 2:
1602 print "xpath extension failure"
1603doc.freeDoc()
1604ctxt.xpathFreeContext()</pre>
1605
1606<p>Note how the extension function is registered with the context (but that
1607part is not yet finalized, ths may change slightly in the future).</p>
1608
1609<h3>tstxpath.py:</h3>
1610
1611<p>This test is similar to the previousone but shows how the extension
1612function can access the XPath evaluation context:</p>
1613<pre>def foo(ctx, x):
1614 global called
1615
1616 #
1617 # test that access to the XPath evaluation contexts
1618 #
1619 pctxt = libxml2.xpathParserContext(_obj=ctx)
1620 ctxt = pctxt.context()
1621 called = ctxt.function()
1622 return x + 1</pre>
1623
1624<p>All the interfaces around the XPath parser(or rather evaluation) context
1625are not finalized, but it should be sufficient to do contextual work at the
1626evaluation point.</p>
1627
1628<h3>Memory debugging:</h3>
1629
1630<p>last but not least, all tests starts with the following prologue:</p>
1631<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1632libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1633
1634<p>and ends with the following epilogue:</p>
1635<pre>#memory debug specific
1636libxml2.cleanupParser()
1637if libxml2.debugMemory(1) == 0:
1638 print "OK"
1639else:
1640 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
1641 libxml2.dumpMemory()</pre>
1642
1643<p>Those activate the memory debugging interface of libxml2 where all
1644alloacted block in the library are tracked. The prologue then cleans up the
1645library state and checks that all allocated memory has been freed. If not it
1646calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1647
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1648<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1649
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1650<p>Libxml is made of multiple components; some of them are optional, and most
1651of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1652<ul>
1653 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1654 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1655 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1656 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1657 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1658 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1659 <li>a SAX tree module to build an in-memory DOM representation</li>
1660 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1661 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1662 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1663 (optional)</li>
1664 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1665</ul>
1666
1667<p>Graphically this gives the following:</p>
1668
1669<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1670
1671<p></p>
1672
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1673<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1674
1675<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1676returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1677<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1678as the file name, the document type, and a <strong>children</strong> pointer
1679which is the root of the document (or more exactly the first child under the
1680root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1681chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1682relationship. An xmlNode can also carry properties (a chain of xmlAttr
1683structures). An attribute may have a value which is a list of TEXT or
1684ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1685
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1686<p>Here is an example (erroneous with respect to the XML spec since there
1687should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1688
1689<p><img src="structure.gif" alt=" structure.gif "></p>
1690
1691<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1692called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1693prints them back as parsed. This is useful for detecting errors both in XML
1694code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1695which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1696result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1697<pre>DOCUMENT
1698version=1.0
1699standalone=true
1700 ELEMENT EXAMPLE
1701 ATTRIBUTE prop1
1702 TEXT
1703 content=gnome is great
1704 ATTRIBUTE prop2
1705 ENTITY_REF
1706 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1707 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1708 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1709 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1710 TEXT
1711 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1712 ELEMENT chapter
1713 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1714 TEXT
1715 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1716 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1717 TEXT
1718 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1719 ELEMENT image
1720 ATTRIBUTE href
1721 TEXT
1722 content=linus.gif
1723 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1724 TEXT
1725 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1726
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1727<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1728
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1729<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1730
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1731<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1732memory. In that case (and if you don't expect to save back the XML document
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1733loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1734a <strong>callback-based interface</strong> to the parser. Before parsing,
1735the application layer registers a customized set of callbacks which are
1736called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1737
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1738<p>To get more detailed step-by-step guidance on using the SAX interface of
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1739libxml, see the <a
1740href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1741documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1742Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1743
1744<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1745program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1746binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1747distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1748testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1749<pre>SAX.setDocumentLocator()
1750SAX.startDocument()
1751SAX.getEntity(amp)
1752SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1753SAX.characters( , 3)
1754SAX.startElement(head)
1755SAX.characters( , 4)
1756SAX.startElement(title)
1757SAX.characters(Welcome to Gnome, 16)
1758SAX.endElement(title)
1759SAX.characters( , 3)
1760SAX.endElement(head)
1761SAX.characters( , 3)
1762SAX.startElement(chapter)
1763SAX.characters( , 4)
1764SAX.startElement(title)
1765SAX.characters(The Linux adventure, 19)
1766SAX.endElement(title)
1767SAX.characters( , 4)
1768SAX.startElement(p)
1769SAX.characters(bla bla bla ..., 15)
1770SAX.endElement(p)
1771SAX.characters( , 4)
1772SAX.startElement(image, href='linus.gif')
1773SAX.endElement(image)
1774SAX.characters( , 4)
1775SAX.startElement(p)
1776SAX.characters(..., 3)
1777SAX.endElement(p)
1778SAX.characters( , 3)
1779SAX.endElement(chapter)
1780SAX.characters( , 1)
1781SAX.endElement(EXAMPLE)
1782SAX.endDocument()</pre>
1783
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1784<p>Most of the other interfaces of libxml are based on the DOM tree-building
1785facility, so nearly everything up to the end of this document presupposes the
1786use of the standard DOM tree build. Note that the DOM tree itself is built by
1787a set of registered default callbacks, without internal specific
1788interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1789
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1790<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1791
1792<p>Table of Content:</p>
1793<ol>
1794 <li><a href="#General5">General overview</a></li>
1795 <li><a href="#definition">The definition</a></li>
1796 <li><a href="#Simple">Simple rules</a>
1797 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1798 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1799 <li><a href="#Declaring">Declaring elements</a></li>
1800 <li><a href="#Declaring1">Declaring attributes</a></li>
1801 </ol>
1802 </li>
1803 <li><a href="#Some">Some examples</a></li>
1804 <li><a href="#validate">How to validate</a></li>
1805 <li><a href="#Other">Other resources</a></li>
1806</ol>
1807
1808<h3><a name="General5">General overview</a></h3>
1809
1810<p>Well what is validation and what is a DTD ?</p>
1811
1812<p>DTD is the acronym for Document Type Definition. This is a description of
1813the content for a familly of XML files. This is part of the XML 1.0
1814specification, and alows to describe and check that a given document instance
1815conforms to a set of rules detailing its structure and content.</p>
1816
1817<p>Validation is the process of checking a document against a DTD (more
1818generally against a set of construction rules).</p>
1819
1820<p>The validation process and building DTDs are the two most difficult parts
1821of the XML life cycle. Briefly a DTD defines all the possibles element to be
1822found within your document, what is the formal shape of your document tree
1823(by defining the allowed content of an element, either text, a regular
1824expression for the allowed list of children, or mixed content i.e. both text
1825and children). The DTD also defines the allowed attributes for all elements
1826and the types of the attributes.</p>
1827
1828<h3><a name="definition1">The definition</a></h3>
1829
1830<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1831href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1832Rev1</a>):</p>
1833<ul>
1834 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1835 elements</a></li>
1836 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1837 attributes</a></li>
1838</ul>
1839
1840<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1841ancient...</p>
1842
1843<h3><a name="Simple1">Simple rules</a></h3>
1844
1845<p>Writing DTD can be done in multiple ways, the rules to build them if you
1846need something fixed or something which can evolve over time can be radically
1847different. Really complex DTD like Docbook ones are flexible but quite harder
1848to design. I will just focuse on DTDs for a formats with a fixed simple
1849structure. It is just a set of basic rules, and definitely not exhaustive nor
1850useable for complex DTD design.</p>
1851
1852<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1853
1854<p>Assuming the top element of the document is <code>spec</code> and the dtd
1855is placed in the file <code>mydtd</code> in the subdirectory
1856<code>dtds</code> of the directory from where the document were loaded:</p>
1857
1858<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1859
1860<p>Notes:</p>
1861<ul>
1862 <li>the system string is actually an URI-Reference (as defined in <a
1863 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1864 full URL string indicating the location of your DTD on the Web, this is a
1865 really good thing to do if you want others to validate your document</li>
1866 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1867 magic string) so that the DTd is looked up in catalogs on the client side
1868 without having to locate it on the web</li>
1869 <li>a dtd contains a set of elements and attributes declarations, but they
1870 don't define what the root of the document should be. This is explicitely
1871 told to the parser/validator as the first element of the
1872 <code>DOCTYPE</code> declaration.</li>
1873</ul>
1874
1875<h4><a name="Declaring2">Declaring elements</a>:</h4>
1876
1877<p>The following declares an element <code>spec</code>:</p>
1878
1879<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1880
1881<p>it also expresses that the spec element contains one <code>front</code>,
1882one <code>body</code> and one optionnal <code>back</code> children elements
1883in this order. The declaration of one element of the structure and its
1884content are done in a single declaration. Similary the following declares
1885<code>div1</code> elements:</p>
1886
Daniel Veillard51737272002-01-23 23:10:38 +0000[diff] [blame]1887<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2?)&gt;</code></p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1888
1889<p>means div1 contains one <code>head</code> then a series of optional
1890<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1891optional <code>div2</code>. And last but not least an element can contain
1892text:</p>
1893
1894<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1895
1896<p><code>b</code> contains text or being of mixed content (text and elements
1897in no particular order):</p>
1898
1899<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1900
1901<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1902<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1903order.</p>
1904
1905<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1906
1907<p>again the attributes declaration includes their content definition:</p>
1908
1909<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1910
1911<p>means that the element <code>termdef</code> can have a <code>name</code>
1912attribute containing text (<code>CDATA</code>) and which is optionnal
1913(<code>#IMPLIED</code>). The attribute value can also be defined within a
1914set:</p>
1915
1916<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1917"ordered"&gt;</code></p>
1918
1919<p>means <code>list</code> element have a <code>type</code> attribute with 3
1920allowed values "bullets", "ordered" or "glossary" and which default to
1921"ordered" if the attribute is not explicitely specified.</p>
1922
1923<p>The content type of an attribute can be text (<code>CDATA</code>),
1924anchor/reference/references
1925(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1926(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1927(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1928<code>chapter</code> element can have an optional <code>id</code> attribute
1929of type <code>ID</code>, usable for reference from attribute of type
1930IDREF:</p>
1931
1932<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1933
1934<p>The last value of an attribute definition can be <code>#REQUIRED
1935</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1936meaning that it is optional, or the default value (possibly prefixed by
1937<code>#FIXED</code> if it is the only allowed).</p>
1938
1939<p>Notes:</p>
1940<ul>
1941 <li>usually the attributes pertaining to a given element are declared in a
1942 single expression, but it is just a convention adopted by a lot of DTD
1943 writers:
1944 <pre>&lt;!ATTLIST termdef
1945 id ID #REQUIRED
1946 name CDATA #IMPLIED&gt;</pre>
1947 <p>The previous construct defines both <code>id</code> and
1948 <code>name</code> attributes for the element <code>termdef</code></p>
1949 </li>
1950</ul>
1951
1952<h3><a name="Some1">Some examples</a></h3>
1953
1954<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1955contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1956example shows an XML file where the simple DTD is directly included within
1957the document.</p>
1958
1959<h3><a name="validate1">How to validate</a></h3>
1960
1961<p>The simplest is to use the xmllint program comming with libxml. The
1962<code>--valid</code> option turn on validation of the files given as input,
1963for example the following validates a copy of the first revision of the XML
19641.0 specification:</p>
1965
1966<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1967
1968<p>the -- noout is used to not output the resulting tree.</p>
1969
1970<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1971a given DTD.</p>
1972
1973<p>Libxml exports an API to handle DTDs and validation, check the <a
1974href="http://xmlsoft.org/html/libxml-valid.html">associated
1975description</a>.</p>
1976
1977<h3><a name="Other1">Other resources</a></h3>
1978
1979<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1980will just list one for now, others pointers welcome:</p>
1981<ul>
1982 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1983</ul>
1984
1985<p>I suggest looking at the examples found under test/valid/dtd and any of
1986the large number of books available on XML. The dia example in test/valid
1987should be both simple and complete enough to allow you to build your own.</p>
1988
1989<p></p>
1990
1991<h2><a name="Memory">Memory Management</a></h2>
1992
1993<p>Table of Content:</p>
1994<ol>
1995 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1996 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1997 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1998 <li><a href="#Debugging">Debugging routines</a></li>
1999 <li><a href="#General4">General memory requirements</a></li>
2000</ol>
2001
2002<h3><a name="General3">General overview</a></h3>
2003
2004<p>The module <code><a
2005href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
2006provides the interfaces to the libxml memory system:</p>
2007<ul>
2008 <li>libxml does not use the libc memory allocator directly but xmlFree(),
2009 xmlMalloc() and xmlRealloc()</li>
2010 <li>those routines can be reallocated to a specific set of routine, by
2011 default the libc ones i.e. free(), malloc() and realloc()</li>
2012 <li>the xmlmemory.c module includes a set of debugging routine</li>
2013</ul>
2014
2015<h3><a name="setting">Setting libxml set of memory routines</a></h3>
2016
2017<p>It is sometimes useful to not use the default memory allocator, either for
2018debugging, analysis or to implement a specific behaviour on memory management
2019(like on embedded systems). Two function calls are available to do so:</p>
2020<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2021 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet
2022 ()</a> which return the current set of functions in use by the parser</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2023 <li><a
2024 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2025 which allow to set up a new set of memory allocation functions</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2026</ul>
2027
2028<p>Of course a call to xmlMemSetup() should probably be done before calling
2029any other libxml routines (unless you are sure your allocations routines are
2030compatibles).</p>
2031
2032<h3><a name="cleanup">Cleaning up after parsing</a></h3>
2033
2034<p>Libxml is not stateless, there is a few set of memory structures needing
2035allocation before the parser is fully functionnal (some encoding structures
2036for example). This also mean that once parsing is finished there is a tiny
2037amount of memory (a few hundred bytes) which can be recollected if you don't
2038reuse the parser immediately:</p>
2039<ul>
2040 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2041 ()</a> is a centralized routine to free the parsing states. Note that it
2042 won't deallocate any produced tree if any (use the xmlFreeDoc() and
2043 related routines for this).</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2044 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2045 ()</a> is the dual routine allowing to preallocate the parsing state
2046 which can be useful for example to avoid initialization reentrancy
2047 problems when using libxml in multithreaded applications</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2048</ul>
2049
2050<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
2051at the next invocation of parser routines, but be careful of the consequences
2052in multithreaded applications.</p>
2053
2054<h3><a name="Debugging">Debugging routines</a></h3>
2055
2056<p>When configured using --with-mem-debug flag (off by default), libxml uses
2057a set of memory allocation debugging routineskeeping track of all allocated
2058blocks and the location in the code where the routine was called. A couple of
2059other debugging routines allow to dump the memory allocated infos to a file
2060or call a specific routine when a given block number is allocated:</p>
2061<ul>
2062 <li><a
2063 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2064 <a
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2065 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
2066 and <a
2067 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
2068 are the memory debugging replacement allocation routines</li>
2069 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2070 ()</a> dumps all the informations about the allocated memory block lefts
2071 in the <code>.memdump</code> file</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2072</ul>
2073
2074<p>When developping libxml memory debug is enabled, the tests programs call
2075xmlMemoryDump () and the "make test" regression tests will check for any
2076memory leak during the full regression test sequence, this helps a lot
2077ensuring that libxml does not leak memory and bullet proof memory
2078allocations use (some libc implementations are known to be far too permissive
2079resulting in major portability problems!).</p>
2080
2081<p>If the .memdump reports a leak, it displays the allocation function and
2082also tries to give some informations about the content and structure of the
2083allocated blocks left. This is sufficient in most cases to find the culprit,
2084but not always. Assuming the allocation problem is reproductible, it is
2085possible to find more easilly:</p>
2086<ol>
2087 <li>write down the block number xxxx not allocated</li>
2088 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
2089 <li>run the program under a debugger and set a breakpoint on
2090 xmlMallocBreakpoint() a specific function called when this precise block
2091 is allocated</li>
2092 <li>when the breakpoint is reached you can then do a fine analysis of the
2093 allocation an step to see the condition resulting in the missing
2094 deallocation.</li>
2095</ol>
2096
2097<p>I used to use a commercial tool to debug libxml memory problems but after
2098noticing that it was not detecting memory leaks that simple mechanism was
2099used and proved extremely efficient until now.</p>
2100
2101<h3><a name="General4">General memory requirements</a></h3>
2102
2103<p>How much libxml memory require ? It's hard to tell in average it depends
2104of a number of things:</p>
2105<ul>
2106 <li>the parser itself should work in a fixed amout of memory, except for
2107 information maintained about the stacks of names and entities locations.
2108 The I/O and encoding handlers will probably account for a few KBytes.
2109 This is true for both the XML and HTML parser (though the HTML parser
2110 need more state).</li>
2111 <li>If you are generating the DOM tree then memory requirements will grow
2112 nearly lineary with the size of the data. In general for a balanced
2113 textual document the internal memory requirement is about 4 times the
2114 size of the UTF8 serialization of this document (exmple the XML-1.0
2115 recommendation is a bit more of 150KBytes and takes 650KBytes of main
2116 memory when parsed). Validation will add a amount of memory required for
2117 maintaining the external Dtd state which should be linear with the
2118 complexity of the content model defined by the Dtd</li>
2119 <li>If you don't care about the advanced features of libxml like
2120 validation, DOM, XPath or XPointer, but really need to work fixed memory
2121 requirements, then the SAX interface should be used.</li>
2122</ul>
2123
2124<p></p>
2125
2126<h2><a name="Encodings">Encodings support</a></h2>
2127
2128<p>Table of Content:</p>
2129<ol>
2130 <li><a href="encoding.html#What">What does internationalization support
2131 mean ?</a></li>
2132 <li><a href="encoding.html#internal">The internal encoding, how and
2133 why</a></li>
2134 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
2135 <li><a href="encoding.html#Default">Default supported encodings</a></li>
2136 <li><a href="encoding.html#extend">How to extend the existing
2137 support</a></li>
2138</ol>
2139
2140<h3><a name="What">What does internationalization support mean ?</a></h3>
2141
2142<p>XML was designed from the start to allow the support of any character set
2143by using Unicode. Any conformant XML parser has to support the UTF-8 and
2144UTF-16 default encodings which can both express the full unicode ranges. UTF8
2145is a variable length encoding whose greatest point are to resuse the same
2146emcoding for ASCII and to save space for Western encodings, but it is a bit
2147more complex to handle in practice. UTF-16 use 2 bytes per characters (and
2148sometimes combines two pairs), it makes implementation easier, but looks a
2149bit overkill for Western languages encoding. Moreover the XML specification
2150allows document to be encoded in other encodings at the condition that they
2151are clearly labelled as such. For example the following is a wellformed XML
2152document encoded in ISO-8859 1 and using accentuated letter that we French
2153likes for both markup and content:</p>
2154<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2155&lt;très&gt;là&lt;/très&gt;</pre>
2156
2157<p>Having internationalization support in libxml means the foolowing:</p>
2158<ul>
2159 <li>the document is properly parsed</li>
2160 <li>informations about it's encoding are saved</li>
2161 <li>it can be modified</li>
2162 <li>it can be saved in its original encoding</li>
2163 <li>it can also be saved in another encoding supported by libxml (for
2164 example straight UTF8 or even an ASCII form)</li>
2165</ul>
2166
2167<p>Another very important point is that the whole libxml API, with the
2168exception of a few routines to read with a specific encoding or save to a
2169specific encoding, is completely agnostic about the original encoding of the
2170document.</p>
2171
2172<p>It should be noted too that the HTML parser embedded in libxml now obbey
2173the same rules too, the following document will be (as of 2.2.2) handled in
2174an internationalized fashion by libxml too:</p>
2175<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
2176 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
2177&lt;html lang="fr"&gt;
2178&lt;head&gt;
2179 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
2180&lt;/head&gt;
2181&lt;body&gt;
2182&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
2183&lt;/html&gt;</pre>
2184
2185<h3><a name="internal">The internal encoding, how and why</a></h3>
2186
2187<p>One of the core decision was to force all documents to be converted to a
2188default internal encoding, and that encoding to be UTF-8, here are the
2189rationale for those choices:</p>
2190<ul>
2191 <li>keeping the native encoding in the internal form would force the libxml
2192 users (or the code associated) to be fully aware of the encoding of the
2193 original document, for examples when adding a text node to a document,
2194 the content would have to be provided in the document encoding, i.e. the
2195 client code would have to check it before hand, make sure it's conformant
2196 to the encoding, etc ... Very hard in practice, though in some specific
2197 cases this may make sense.</li>
2198 <li>the second decision was which encoding. From the XML spec only UTF8 and
2199 UTF16 really makes sense as being the two only encodings for which there
2200 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
2201 considered an intelligent choice too since it's a direct Unicode mapping
2202 support. I selected UTF-8 on the basis of efficiency and compatibility
2203 with surrounding software:
2204 <ul>
2205 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
2206 more costly to import and export CPU wise) is also far more compact
2207 than UTF-16 (and UCS-4) for a majority of the documents I see it used
2208 for right now (RPM RDF catalogs, advogato data, various configuration
2209 file formats, etc.) and the key point for today's computer
2210 architecture is efficient uses of caches. If one nearly double the
2211 memory requirement to store the same amount of data, this will trash
2212 caches (main memory/external caches/internal caches) and my take is
2213 that this harms the system far more than the CPU requirements needed
2214 for the conversion to UTF-8</li>
2215 <li>Most of libxml version 1 users were using it with straight ASCII
2216 most of the time, doing the conversion with an internal encoding
2217 requiring all their code to be rewritten was a serious show-stopper
2218 for using UTF-16 or UCS-4.</li>
2219 <li>UTF-8 is being used as the de-facto internal encoding standard for
2220 related code like the <a href="http://www.pango.org/">pango</a>
2221 upcoming Gnome text widget, and a lot of Unix code (yep another place
2222 where Unix programmer base takes a different approach from Microsoft
2223 - they are using UTF-16)</li>
2224 </ul>
2225 </li>
2226</ul>
2227
2228<p>What does this mean in practice for the libxml user:</p>
2229<ul>
2230 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
2231 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
2232 is simply to append 0 byte, as usual.</li>
2233 <li>One just need to make sure that when using chars outside the ASCII set,
2234 the values has been properly converted to UTF-8</li>
2235</ul>
2236
2237<h3><a name="implemente">How is it implemented ?</a></h3>
2238
2239<p>Let's describe how all this works within libxml, basically the I18N
2240(internationalization) support get triggered only during I/O operation, i.e.
2241when reading a document or saving one. Let's look first at the reading
2242sequence:</p>
2243<ol>
2244 <li>when a document is processed, we usually don't know the encoding, a
2245 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
2246 ASCII range (0-0x7F) maps with ASCII</li>
2247 <li>the xml declaration if available is parsed, including the encoding
2248 declaration. At that point, if the autodetected encoding is different
2249 from the one declared a call to xmlSwitchEncoding() is issued.</li>
2250 <li>If there is no encoding declaration, then the input has to be in either
2251 UTF-8 or UTF-16, if it is not then at some point when processing the
2252 input, the converter/checker of UTF-8 form will raise an encoding error.
2253 You may end-up with a garbled document, or no document at all ! Example:
2254 <pre>~/XML -&gt; ./xmllint err.xml
2255err.xml:1: error: Input is not proper UTF-8, indicate encoding !
2256&lt;très&gt;là&lt;/très&gt;
2257 ^
2258err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
2259&lt;très&gt;là&lt;/très&gt;
2260 ^</pre>
2261 </li>
2262 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
2263 then search the default registered encoding converters for that encoding.
2264 If it's not within the default set and iconv() support has been compiled
2265 it, it will ask iconv for such an encoder. If this fails then the parser
2266 will report an error and stops processing:
2267 <pre>~/XML -&gt; ./xmllint err2.xml
2268err2.xml:1: error: Unsupported encoding UnsupportedEnc
2269&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
2270 ^</pre>
2271 </li>
2272 <li>From that point the encoder process progressingly the input (it is
2273 plugged as a front-end to the I/O module) for that entity. It captures
2274 and convert on-the-fly the document to be parsed to UTF-8. The parser
2275 itself just does UTF-8 checking of this input and process it
2276 transparently. The only difference is that the encoding information has
2277 been added to the parsing context (more precisely to the input
2278 corresponding to this entity).</li>
2279 <li>The result (when using DOM) is an internal form completely in UTF-8
2280 with just an encoding information on the document node.</li>
2281</ol>
2282
2283<p>Ok then what's happen when saving the document (assuming you
2284colllected/built an xmlDoc DOM like structure) ? It depends on the function
2285called, xmlSaveFile() will just try to save in the original encoding, while
2286xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
2287encoding:</p>
2288<ol>
2289 <li>if no encoding is given, libxml will look for an encoding value
2290 associated to the document and if it exists will try to save to that
2291 encoding,
2292 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
2293 </li>
2294 <li>so if an encoding was specified, either at the API level or on the
2295 document, libxml will again canonalize the encoding name, lookup for a
2296 converter in the registered set or through iconv. If not found the
2297 function will return an error code</li>
2298 <li>the converter is placed before the I/O buffer layer, as another kind of
2299 buffer, then libxml will simply push the UTF-8 serialization to through
2300 that buffer, which will then progressively be converted and pushed onto
2301 the I/O layer.</li>
2302 <li>It is possible that the converter code fails on some input, for example
2303 trying to push an UTF-8 encoded chinese character through the UTF-8 to
2304 ISO-8859-1 converter won't work. Since the encoders are progressive they
2305 will just report the error and the number of bytes converted, at that
2306 point libxml will decode the offending character, remove it from the
2307 buffer and replace it with the associated charRef encoding &amp;#123; and
2308 resume the convertion. This guarante that any document will be saved
2309 without losses (except for markup names where this is not legal, this is
2310 a problem in the current version, in pactice avoid using non-ascci
2311 characters for tags or attributes names @@). A special "ascii" encoding
2312 name is used to save documents to a pure ascii form can be used when
2313 portability is really crucial</li>
2314</ol>
2315
2316<p>Here is a few examples based on the same test document:</p>
2317<pre>~/XML -&gt; ./xmllint isolat1
2318&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2319&lt;très&gt;là&lt;/très&gt;
2320~/XML -&gt; ./xmllint --encode UTF-8 isolat1
2321&lt;?xml version="1.0" encoding="UTF-8"?&gt;
2322&lt;très&gt;là  &lt;/très&gt;
2323~/XML -&gt; </pre>
2324
2325<p>The same processing is applied (and reuse most of the code) for HTML I18N
2326processing. Looking up and modifying the content encoding is a bit more
2327difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
2328so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
2329been provided. The parser also attempts to switch encoding on the fly when
2330detecting such a tag on input. Except for that the processing is the same
2331(and again reuses the same code).</p>
2332
2333<h3><a name="Default">Default supported encodings</a></h3>
2334
2335<p>libxml has a set of default converters for the following encodings
2336(located in encoding.c):</p>
2337<ol>
2338 <li>UTF-8 is supported by default (null handlers)</li>
2339 <li>UTF-16, both little and big endian</li>
2340 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
2341 <li>ASCII, useful mostly for saving</li>
2342 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
2343 predefined entities like &amp;copy; for the Copyright sign.</li>
2344</ol>
2345
2346<p>More over when compiled on an Unix platfor with iconv support the full set
2347of encodings supported by iconv can be instantly be used by libxml. On a
2348linux machine with glibc-2.1 the list of supported encodings and aliases fill
23493 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
2350various Japanese ones.</p>
2351
2352<h4>Encoding aliases</h4>
2353
2354<p>From 2.2.3, libxml has support to register encoding names aliases. The
2355goal is to be able to parse document whose encoding is supported but where
2356the name differs (for example from the default set of names accepted by
2357iconv). The following functions allow to register and handle new aliases for
2358existing encodings. Once registered libxml will automatically lookup the
2359aliases when handling a document:</p>
2360<ul>
2361 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
2362 <li>int xmlDelEncodingAlias(const char *alias);</li>
2363 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
2364 <li>void xmlCleanupEncodingAliases(void);</li>
2365</ul>
2366
2367<h3><a name="extend">How to extend the existing support</a></h3>
2368
2369<p>Well adding support for new encoding, or overriding one of the encoders
2370(assuming it is buggy) should not be hard, just write an input and output
2371conversion routines to/from UTF-8, and register them using
2372xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
2373called automatically if the parser(s) encounter such an encoding name
2374(register it uppercase, this will help). The description of the encoders,
2375their arguments and expected return values are described in the encoding.h
2376header.</p>
2377
2378<p>A quick note on the topic of subverting the parser to use a different
2379internal encoding than UTF-8, in some case people will absolutely want to
2380keep the internal encoding different, I think it's still possible (but the
2381encoding must be compliant with ASCII on the same subrange) though I didn't
2382tried it. The key is to override the default conversion routines (by
2383registering null encoders/decoders for your charsets), and bypass the UTF-8
2384checking of the parser by setting the parser context charset
2385(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2386there is no guarantee taht this will work. You may also have some troubles
2387saving back.</p>
2388
2389<p>Basically proper I18N support is important, this requires at least
2390libxml-2.0.0, but a lot of features and corrections are really available only
2391starting 2.2.</p>
2392
2393<h2><a name="IO">I/O Interfaces</a></h2>
2394
2395<p>Table of Content:</p>
2396<ol>
2397 <li><a href="#General1">General overview</a></li>
2398 <li><a href="#basic">The basic buffer type</a></li>
2399 <li><a href="#Input">Input I/O handlers</a></li>
2400 <li><a href="#Output">Output I/O handlers</a></li>
2401 <li><a href="#entities">The entities loader</a></li>
2402 <li><a href="#Example2">Example of customized I/O</a></li>
2403</ol>
2404
2405<h3><a name="General1">General overview</a></h3>
2406
2407<p>The module <code><a
2408href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2409the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2410<ul>
2411 <li>Entities loader, this is a routine which tries to fetch the entities
2412 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2413 don't look at the public identifier since libxml do not maintain a
2414 catalog. You can redefine you own entity loader by using
2415 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2416 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2417 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2418 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2419 input layer to handle fetching the informations to feed the parser. This
2420 provides buffering and is also a placeholder where the encoding
2421 convertors to UTF8 are piggy-backed.</li>
2422 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2423 task but when generating a serialization from a tree.</li>
2424 <li>A mechanism to register sets of I/O callbacks and associate them with
2425 specific naming schemes like the protocol part of the URIs.
2426 <p>This affect the default I/O operations and allows to use specific I/O
2427 handlers for certain names.</p>
2428 </li>
2429</ul>
2430
2431<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2432example in the HTML parser is the following:</p>
2433<ol>
2434 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2435 the parsing context and the URI string.</li>
2436 <li>the URI string is checked against the existing registered handlers
2437 using their match() callback function, if the HTTP module was compiled
2438 in, it is registered and its match() function will succeeds</li>
2439 <li>the open() function of the handler is called and if successful will
2440 return an I/O Input buffer</li>
2441 <li>the parser will the start reading from this buffer and progressively
2442 fetch information from the resource, calling the read() function of the
2443 handler until the resource is exhausted</li>
2444 <li>if an encoding change is detected it will be installed on the input
2445 buffer, providing buffering and efficient use of the conversion
2446 routines</li>
2447 <li>once the parser has finished, the close() function of the handler is
2448 called once and the Input buffer and associed resources are
2449 deallocated.</li>
2450</ol>
2451
2452<p>The user defined callbacks are checked first to allow overriding of the
2453default libxml I/O routines.</p>
2454
2455<h3><a name="basic">The basic buffer type</a></h3>
2456
2457<p>All the buffer manipulation handling is done using the
2458<code>xmlBuffer</code> type define in <code><a
2459href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2460resizable memory buffer. The buffer allocation strategy can be selected to be
2461either best-fit or use an exponential doubling one (CPU vs. memory use
2462tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2463<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2464system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2465of functions allows to manipulate buffers with names starting with the
2466<code>xmlBuffer...</code> prefix.</p>
2467
2468<h3><a name="Input">Input I/O handlers</a></h3>
2469
2470<p>An Input I/O handler is a simple structure
2471<code>xmlParserInputBuffer</code> containing a context associated to the
2472resource (file descriptor, or pointer to a protocol handler), the read() and
2473close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2474encoding handler are also present to support charset conversion when
2475needed.</p>
2476
2477<h3><a name="Output">Output I/O handlers</a></h3>
2478
2479<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2480Input one except the callbacks are write() and close().</p>
2481
2482<h3><a name="entities">The entities loader</a></h3>
2483
2484<p>The entity loader resolves requests for new entities and create inputs for
2485the parser. Creating an input from a filename or an URI string is done
2486through the xmlNewInputFromFile() routine. The default entity loader do not
2487handle the PUBLIC identifier associated with an entity (if any). So it just
2488calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2489XML).</p>
2490
2491<p>If you want to hook up a catalog mechanism then you simply need to
2492override the default entity loader, here is an example:</p>
2493<pre>#include &lt;libxml/xmlIO.h&gt;
2494
2495xmlExternalEntityLoader defaultLoader = NULL;
2496
2497xmlParserInputPtr
2498xmlMyExternalEntityLoader(const char *URL, const char *ID,
2499 xmlParserCtxtPtr ctxt) {
2500 xmlParserInputPtr ret;
2501 const char *fileID = NULL;
2502 /* lookup for the fileID depending on ID */
2503
2504 ret = xmlNewInputFromFile(ctxt, fileID);
2505 if (ret != NULL)
2506 return(ret);
2507 if (defaultLoader != NULL)
2508 ret = defaultLoader(URL, ID, ctxt);
2509 return(ret);
2510}
2511
2512int main(..) {
2513 ...
2514
2515 /*
2516 * Install our own entity loader
2517 */
2518 defaultLoader = xmlGetExternalEntityLoader();
2519 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2520
2521 ...
2522}</pre>
2523
2524<h3><a name="Example2">Example of customized I/O</a></h3>
2525
2526<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2527real use case</a>, xmlDocDump() closes the FILE * passed by the application
2528and this was a problem. The <a
2529href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2530new output handler with the closing call deactivated:</p>
2531<ol>
2532 <li>First define a new I/O ouput allocator where the output don't close the
2533 file:
2534 <pre>xmlOutputBufferPtr
2535xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2536    xmlOutputBufferPtr ret;
2537    
2538    if (xmlOutputCallbackInitialized == 0)
2539        xmlRegisterDefaultOutputCallbacks();
2540
2541    if (file == NULL) return(NULL);
2542    ret = xmlAllocOutputBuffer(encoder);
2543    if (ret != NULL) {
2544        ret-&gt;context = file;
2545        ret-&gt;writecallback = xmlFileWrite;
2546        ret-&gt;closecallback = NULL; /* No close callback */
2547    }
2548    return(ret); <br>
Daniel Veillard1eb24242002-03-18 11:33:03 +0000[diff] [blame]2549
Daniel Veillard34ce8be2002-03-18 19:37:11 +0000[diff] [blame]2550
2551
Daniel Veillard19274092002-03-25 16:48:03 +0000[diff] [blame^]2552
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2553} </pre>
2554 </li>
2555 <li>And then use it to save the document:
2556 <pre>FILE *f;
2557xmlOutputBufferPtr output;
2558xmlDocPtr doc;
2559int res;
2560
2561f = ...
2562doc = ....
2563
2564output = xmlOutputBufferCreateOwn(f, NULL);
2565res = xmlSaveFileTo(output, doc, NULL);
2566 </pre>
2567 </li>
2568</ol>
2569
2570<h2><a name="Catalog">Catalog support</a></h2>
2571
2572<p>Table of Content:</p>
2573<ol>
2574 <li><a href="General2">General overview</a></li>
2575 <li><a href="#definition">The definition</a></li>
2576 <li><a href="#Simple">Using catalogs</a></li>
2577 <li><a href="#Some">Some examples</a></li>
2578 <li><a href="#reference">How to tune catalog usage</a></li>
2579 <li><a href="#validate">How to debug catalog processing</a></li>
2580 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2581 <li><a href="#implemento">The implementor corner quick review of the
2582 API</a></li>
2583 <li><a href="#Other">Other resources</a></li>
2584</ol>
2585
2586<h3><a name="General2">General overview</a></h3>
2587
2588<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2589(a file or a remote resource) references another entity. The catalog lookup
2590is inserted between the moment the reference is recognized by the software
2591(XML parser, stylesheet processing, or even images referenced for inclusion
2592in a rendering) and the time where loading that resource is actually
2593started.</p>
2594
2595<p>It is basically used for 3 things:</p>
2596<ul>
2597 <li>mapping from "logical" names, the public identifiers and a more
2598 concrete name usable for download (and URI). For example it can associate
2599 the logical name
2600 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2601 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2602 downloaded</p>
2603 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2604 </li>
2605 <li>remapping from a given URL to another one, like an HTTP indirection
2606 saying that
2607 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2608 <p>should really be looked at</p>
2609 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2610 </li>
2611 <li>providing a local cache mechanism allowing to load the entities
2612 associated to public identifiers or remote resources, this is a really
2613 important feature for any significant deployment of XML or SGML since it
2614 allows to avoid the aleas and delays associated to fetching remote
2615 resources.</li>
2616</ul>
2617
2618<h3><a name="definition">The definitions</a></h3>
2619
2620<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2621<ul>
2622 <li>the older SGML catalogs, the official spec is SGML Open Technical
2623 Resolution TR9401:1997, but is better understood by reading <a
2624 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2625 James Clark. This is relatively old and not the preferred mode of
2626 operation of libxml.</li>
2627 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2628 Catalogs</a> is far more flexible, more recent, uses an XML syntax and
2629 should scale quite better. This is the default option of libxml.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2630</ul>
2631
2632<p></p>
2633
2634<h3><a name="Simple">Using catalog</a></h3>
2635
2636<p>In a normal environment libxml will by default check the presence of a
2637catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2638the processing is completely transparent to the document user. To take a
2639concrete example, suppose you are authoring a DocBook document, this one
2640starts with the following DOCTYPE definition:</p>
2641<pre>&lt;?xml version='1.0'?&gt;
2642&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2643 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2644
2645<p>When validating the document with libxml, the catalog will be
2646automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2647DocBk XML V3.1.4//EN" and the system identifier
2648"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2649been installed on your system and the catalogs actually point to them, libxml
2650will fetch them from the local disk.</p>
2651
2652<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2653DOCTYPE example it's a really old version, but is fine as an example.</p>
2654
2655<p>Libxml will check the catalog each time that it is requested to load an
2656entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2657your system is correctly configured all the authoring phase and processing
2658should use only local files, even if your document stays portable because it
2659uses the canonical public and system ID, referencing the remote document.</p>
2660
2661<h3><a name="Some">Some examples:</a></h3>
2662
2663<p>Here is a couple of fragments from XML Catalogs used in libxml early
2664regression tests in <code>test/catalogs</code> :</p>
2665<pre>&lt;?xml version="1.0"?&gt;
2666&lt;!DOCTYPE catalog PUBLIC
2667 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2668 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2669&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2670 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2671 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2672...</pre>
2673
2674<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2675written in XML, there is a specific namespace for catalog elements
2676"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2677catalog is a <code>public</code> mapping it allows to associate a Public
2678Identifier with an URI.</p>
2679<pre>...
2680 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2681 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2682...</pre>
2683
2684<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2685any URI starting with a given prefix should be looked at another URI
2686constructed by replacing the prefix with an new one. In effect this acts like
2687a cache system for a full area of the Web. In practice it is extremely useful
2688with a file prefix if you have installed a copy of those resources on your
2689local system.</p>
2690<pre>...
2691&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2692 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2693&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2694 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2695&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2696 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2697&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2698 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2699&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2700 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2701...</pre>
2702
2703<p>Delegation is the core features which allows to build a tree of catalogs,
2704easier to maintain than a single catalog, based on Public Identifier, System
2705Identifier or URI prefixes it instructs the catalog software to look up
2706entries in another resource. This feature allow to build hierarchies of
2707catalogs, the set of entries presented should be sufficient to redirect the
2708resolution of all DocBook references to the specific catalog in
2709<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2710references for DocBook 4.2.1 to a specific catalog installed at the same time
2711as the DocBook resources on the local machine.</p>
2712
2713<h3><a name="reference">How to tune catalog usage:</a></h3>
2714
2715<p>The user can change the default catalog behaviour by redirecting queries
2716to its own set of catalogs, this can be done by setting the
2717<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2718empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2719default catalog</p>
2720
2721<h3><a name="validate">How to debug catalog processing:</a></h3>
2722
2723<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2724make libxml output debugging informations for each catalog operations, for
2725example:</p>
2726<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2727warning: failed to load external entity "title.xml"
2728orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2729orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2730Failed to parse catalog /etc/xml/catalog
2731Failed to parse catalog /etc/xml/catalog
2732warning: failed to load external entity "title.xml"
2733Catalogs cleanup
2734orchis:~/XML -&gt; </pre>
2735
2736<p>The test/ent2 references an entity, running the parser from memory makes
2737the base URI unavailable and the the "title.xml" entity cannot be loaded.
2738Setting up the debug environment variable allows to detect that an attempt is
2739made to load the <code>/etc/xml/catalog</code> but since it's not present the
2740resolution fails.</p>
2741
2742<p>But the most advanced way to debug XML catalog processing is to use the
2743<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2744catalogs and make resolution queries to see what is going on. This is also
2745used for the regression tests:</p>
2746<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2747 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2748http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2749orchis:~/XML -&gt; </pre>
2750
2751<p>For debugging what is going on, adding one -v flags increase the verbosity
2752level to indicate the processing done (adding a second flag also indicate
2753what elements are recognized at parsing):</p>
2754<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2755 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2756Parsing catalog test/catalogs/docbook.xml's content
2757Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2758http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2759Catalogs cleanup
2760orchis:~/XML -&gt; </pre>
2761
2762<p>A shell interface is also available to debug and process multiple queries
2763(and for regression tests):</p>
2764<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2765 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2766&gt; help
2767Commands available:
2768public PublicID: make a PUBLIC identifier lookup
2769system SystemID: make a SYSTEM identifier lookup
2770resolve PublicID SystemID: do a full resolver lookup
2771add 'type' 'orig' 'replace' : add an entry
2772del 'values' : remove values
2773dump: print the current catalog state
2774debug: increase the verbosity level
2775quiet: decrease the verbosity level
2776exit: quit the shell
2777&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2778http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2779&gt; quit
2780orchis:~/XML -&gt; </pre>
2781
2782<p>This should be sufficient for most debugging purpose, this was actually
2783used heavily to debug the XML Catalog implementation itself.</p>
2784
2785<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2786
2787<p>Basically XML Catalogs are XML files, you can either use XML tools to
2788manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2789to create a catalog the -create option provide this facility:</p>
2790<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2791&lt;?xml version="1.0"?&gt;
2792&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2793 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2794&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2795orchis:~/XML -&gt; </pre>
2796
2797<p>By default xmlcatalog does not overwrite the original catalog and save the
2798result on the standard output, this can be overridden using the -noout
2799option. The <code>-add</code> command allows to add entries in the
2800catalog:</p>
2801<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2802 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2803 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2804orchis:~/XML -&gt; cat tst.xml
2805&lt;?xml version="1.0"?&gt;
2806&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2807 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2808&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2809&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2810 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2811&lt;/catalog&gt;
2812orchis:~/XML -&gt; </pre>
2813
2814<p>The <code>-add</code> option will always take 3 parameters even if some of
2815the XML Catalog constructs (like nextCatalog) will have only a single
2816argument, just pass a third empty string, it will be ignored.</p>
2817
2818<p>Similarly the <code>-del</code> option remove matching entries from the
2819catalog:</p>
2820<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2821 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2822&lt;?xml version="1.0"?&gt;
2823&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2824 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2825&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2826orchis:~/XML -&gt; </pre>
2827
2828<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2829exact and would have worked in a similar fashion with the Public ID
2830string.</p>
2831
2832<p>This is rudimentary but should be sufficient to manage a not too complex
2833catalog tree of resources.</p>
2834
2835<h3><a name="implemento">The implementor corner quick review of the
2836API:</a></h3>
2837
2838<p>First, and like for every other module of libxml, there is an
2839automatically generated <a href="html/libxml-catalog.html">API page for
2840catalog support</a>.</p>
2841
2842<p>The header for the catalog interfaces should be included as:</p>
2843<pre>#include &lt;libxml/catalog.h&gt;</pre>
2844
2845<p>The API is voluntarily kept very simple. First it is not obvious that
2846applications really need access to it since it is the default behaviour of
2847libxml (Note: it is possible to completely override libxml default catalog by
2848using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2849plug an application specific resolver).</p>
2850
2851<p>Basically libxml support 2 catalog lists:</p>
2852<ul>
2853 <li>the default one, global shared by all the application</li>
2854 <li>a per-document catalog, this one is built if the document uses the
2855 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2856 associated to the parser context and destroyed when the parsing context
2857 is destroyed.</li>
2858</ul>
2859
2860<p>the document one will be used first if it exists.</p>
2861
2862<h4>Initialization routines:</h4>
2863
2864<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2865used at startup to initialize the catalog, if the catalog should be
2866initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2867should be called before xmlInitializeCatalog() which would otherwise do a
2868default initialization first.</p>
2869
2870<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2871own catalog list if needed.</p>
2872
2873<h4>Preferences setup:</h4>
2874
2875<p>The XML Catalog spec requires the possibility to select default
2876preferences between public and system delegation,
2877xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2878xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2879be forbidden, allowed for global catalog, for document catalog or both, the
2880default is to allow both.</p>
2881
2882<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2883(through the xmlGenericError() mechanism).</p>
2884
2885<h4>Querying routines:</h4>
2886
2887<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2888and xmlCatalogResolveURI() are relatively explicit if you read the XML
2889Catalog specification they correspond to section 7 algorithms, they should
2890also work if you have loaded an SGML catalog with a simplified semantic.</p>
2891
2892<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2893operate on the document catalog list</p>
2894
2895<h4>Cleanup and Miscellaneous:</h4>
2896
2897<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2898the per-document equivalent.</p>
2899
2900<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2901first catalog in the global list, and xmlCatalogDump() allows to dump a
2902catalog state, those routines are primarily designed for xmlcatalog, I'm not
2903sure that exposing more complex interfaces (like navigation ones) would be
2904really useful.</p>
2905
2906<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2907it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2908provided because this functionality may be useful for client tools.</p>
2909
2910<h4>threaded environments:</h4>
2911
2912<p>Since the catalog tree is built progressively, some care has been taken to
2913try to avoid troubles in multithreaded environments. The code is now thread
2914safe assuming that the libxml library has been compiled with threads
2915support.</p>
2916
2917<p></p>
2918
2919<h3><a name="Other">Other resources</a></h3>
2920
2921<p>The XML Catalog specification is relatively recent so there isn't much
2922literature to point at:</p>
2923<ul>
2924 <li>You can find an good rant from Norm Walsh about <a
2925 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2926 need for catalogs</a>, it provides a lot of context informations even if
2927 I don't agree with everything presented.</li>
2928 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2929 catalog proposal</a> from John Cowan</li>
2930 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2931 Language</a> (RDDL) another catalog system but more oriented toward
2932 providing metadata for XML namespaces.</li>
2933 <li>the page from the OASIS Technical <a
2934 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2935 Resolution</a> who maintains XML Catalog, you will find pointers to the
2936 specification update, some background and pointers to others tools
2937 providing XML Catalog support</li>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2938 <li>Here is a <a href="buildDocBookCatalog">shell script</a> to generate
2939 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/
2940 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on
2941 the resources found on the system. Otherwise it will just create
2942 ~/xmlcatalog and ~/dbkxmlcatalog and doing:
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2943 <p><code>export XMLCATALOG=$HOME/xmlcatalog</code></p>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2944 <p>should allow to process DocBook documentations without requiring
2945 network accesses for the DTd or stylesheets</p>
2946 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2947 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2948 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems
2949 to work fine for me too</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2950 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2951 manual page</a></li>
2952</ul>
2953
2954<p>If you have suggestions for corrections or additions, simply contact
2955me:</p>
2956
2957<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2958
2959<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2960using the XML library from the C language. It is not intended to be
2961extensive. I hope the automatically generated documents will provide the
2962completeness required, but as a separate set of documents. The interfaces of
2963the XML library are by principle low level, there is nearly zero abstraction.
2964Those interested in a higher level API should <a href="#DOM">look at
2965DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2966
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2967<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2968separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2969interfaces</a>. Let's have a look at how the XML parser can be called:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2970
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2971<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2972
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2973<p>Usually, the first thing to do is to read an XML input. The parser accepts
2974documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2975defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2976<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2977 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2978 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2979 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2980</dl>
2981<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2982 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2983 <dd><p>Parse an XML document contained in a (possibly compressed)
2984 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2985 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2986</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2987
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2988<p>The parser returns a pointer to the document structure (or NULL in case of
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2989failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2990
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2991<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2992
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2993<p>In order for the application to keep the control when the document is
2994being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2995interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2996<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2997 void *user_data,
2998 const char *chunk,
2999 int size,
3000 const char *filename);
3001int xmlParseChunk (xmlParserCtxtPtr ctxt,
3002 const char *chunk,
3003 int size,
3004 int terminate);</pre>
3005
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3006<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3007<pre> FILE *f;
3008
3009 f = fopen(filename, "r");
3010 if (f != NULL) {
3011 int res, size = 1024;
3012 char chars[1024];
3013 xmlParserCtxtPtr ctxt;
3014
3015 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3016 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3017 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
3018 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3019 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3020 xmlParseChunk(ctxt, chars, res, 0);
3021 }
3022 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3023 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3024 xmlFreeParserCtxt(ctxt);
3025 }
3026 }</pre>
3027
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3028<p>The HTML parser embedded into libxml also has a push interface; the
3029functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3030
3031<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
3032
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3033<p>The tree-building interface makes the parser memory-hungry, first loading
3034the document in memory and then building the tree itself. Reading a document
3035without building the tree is possible using the SAX interfaces (see SAX.h and
3036<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3037Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3038limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3039<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3040
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3041<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3042
3043<p>The other way to get an XML tree in memory is by building it. Basically
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3044there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3045also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
3046code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3047<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3048 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3049 xmlNodePtr tree, subtree;
3050
3051 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3052 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
3053 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
3054 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
3055 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3056 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3057 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3058 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
3059 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
3060 subtree = xmlNewChild(tree, NULL, "image", NULL);
3061 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3062
3063<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3064
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3065<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3066
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3067<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3068code has access to the internal structure of all the elements of the tree.
3069The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]3070<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3071<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3072example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3073<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3074
3075<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3076<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3077
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3078<p>points to the text node containing the chapter title "The Linux
3079adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3080
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3081<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3082present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3083to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]3084<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3085
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3086<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3087
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3088<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3089is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3090<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3091 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
3092 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3093 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
3094 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3095 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3096</dl>
3097<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3098 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3099 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]3100 <dd><p>This function returns a pointer to new copy of the property
3101 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3102 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3103</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3104
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3105<p>Two functions are provided for reading and writing the text associated
3106with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3107<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3108 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3109 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3110 <dd><p>This function takes an "external" string and converts it to one
3111 text node or possibly to a list of entity and text nodes. All
3112 non-predefined entity references like &amp;Gnome; will be stored
3113 internally as entity nodes, hence the result of the function may not be
3114 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3115 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3116</dl>
3117<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3118 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3119 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3120 <dd><p>This function is the inverse of
3121 <code>xmlStringGetNodeList()</code>. It generates a new string
3122 containing the content of the text and entity nodes. Note the extra
3123 argument inLine. If this argument is set to 1, the function will expand
3124 entity references. For example, instead of returning the &amp;Gnome;
3125 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3126 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3127 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3128</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3129
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3130<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3131
3132<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3133<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3134 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3135 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3136 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3137 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3138</dl>
3139<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3140 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3141 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3142 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3143</dl>
3144<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3145 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3146 <dd><p>Saves the document to a file. In this case, the compression
3147 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3148 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3149</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3150
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3151<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3152
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3153<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3154accesses. The level of compression on saves can be turned on either globally
3155or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3156<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3157 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3158 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3159 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3160</dl>
3161<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3162 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3163 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3164 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3165</dl>
3166<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3167 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3168 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3169 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3170</dl>
3171<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3172 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3173 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3174 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3175</dl>
3176
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3177<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3178
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3179<p>Entities in principle are similar to simple C macros. An entity defines an
3180abbreviation for a given string that you can reuse many times throughout the
3181content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3182may occur frequently within a document, or to confine the change needed to a
3183document to a restricted area in the internal subset of the document (at the
3184beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3185<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31862 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31873 &lt;!ENTITY xml "Extensible Markup Language"&gt;
31884 ]&gt;
31895 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31906 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31917 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3192
3193<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3194its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3195are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3196predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3197<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3198for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3199<strong>&amp;quot;</strong> for the character '"', and
3200<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3201
3202<p>One of the problems related to entities is that you may want the parser to
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3203substitute an entity's content so that you can see the replacement text in
3204your application. Or you may prefer to keep entity references as such in the
3205content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3206precious information (if the user went through the pain of explicitly
3207defining entities, he may have a a rather negative attitude if you blindly
3208susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3209href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3210function allows you to check and change the behaviour, which is to not
3211substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3212
3213<p>Here is the DOM tree built by libxml for the previous document in the
3214default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3215<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3216DOCUMENT
3217version=1.0
3218 ELEMENT EXAMPLE
3219 TEXT
3220 content=
3221 ENTITY_REF
3222 INTERNAL_GENERAL_ENTITY xml
3223 content=Extensible Markup Language
3224 TEXT
3225 content=</pre>
3226
3227<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3228<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3229DOCUMENT
3230version=1.0
3231 ELEMENT EXAMPLE
3232 TEXT
3233 content= Extensible Markup Language</pre>
3234
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3235<p>So, entities or no entities? Basically, it depends on your use case. I
3236suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3237entities in your XML document or data if you are not willing to handle the
3238entity references elements in the DOM tree.</p>
3239
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3240<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3241entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3242transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3243reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3244finding them in the input).</p>
3245
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3246<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3247on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3248non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3249then using the SAX API may be long. If you plan to use complex documents, I
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3250strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]3251deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3252
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3253<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3254
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3255<p>The libxml library implements <a
3256href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
3257recognizing namespace contructs in the input, and does namespace lookup
3258automatically when building the DOM tree. A namespace declaration is
3259associated with an in-memory structure and all elements or attributes within
3260that namespace point to it. Hence testing the namespace is a simple and fast
3261equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3262
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3263<p>I suggest that people using libxml use a namespace, and declare it in the
3264root element of their document as the default namespace. Then they don't need
3265to use the prefix in the content but we will have a basis for future semantic
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3266refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3267the size of the XML output significantly, but significantly increases its
3268value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3269<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
3270 &lt;elem1&gt;...&lt;/elem1&gt;
3271 &lt;elem2&gt;...&lt;/elem2&gt;
3272&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3273
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3274<p>The namespace value has to be an absolute URL, but the URL doesn't have to
3275point to any existing resource on the Web. It will bind all the element and
3276atributes with that URL. I suggest to use an URL within a domain you control,
3277and that the URL should contain some kind of version information if possible.
3278For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
3279namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3280
3281<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3282version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3283and if the version information don't match something you know, warn the user
3284and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3285namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3286same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3287associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3288just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3289<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3290prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3291
3292<p>@@Interfaces@@</p>
3293
3294<p>@@Examples@@</p>
3295
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3296<p>Usually people object to using namespaces together with validity checking.
3297I will try to make sure that using namespaces won't break validity checking,
3298so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3299suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3300<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3301flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3302from multiple DTDs will certainly break current validation schemes. I will
3303try to provide ways to do this, but this may not be portable or
3304standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3305
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3306<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3307
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3308<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3309
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3310<p>Version 2 of libxml is the first version introducing serious backward
3311incompatible changes. The main goals were:</p>
3312<ul>
3313 <li>a general cleanup. A number of mistakes inherited from the very early
3314 versions couldn't be changed due to compatibility constraints. Example
3315 the "childs" element in the nodes.</li>
3316 <li>Uniformization of the various nodes, at least for their header and link
3317 parts (doc, parent, children, prev, next), the goal is a simpler
3318 programming model and simplifying the task of the DOM implementors.</li>
3319 <li>better conformances to the XML specification, for example version 1.x
3320 had an heuristic to try to detect ignorable white spaces. As a result the
3321 SAX event generated were ignorableWhitespace() while the spec requires
3322 character() in that case. This also mean that a number of DOM node
3323 containing blank text may populate the DOM tree which were not present
3324 before.</li>
3325</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3326
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3327<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3328
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3329<p>So client code of libxml designed to run with version 1.x may have to be
3330changed to compile against version 2.x of libxml. Here is a list of changes
3331that I have collected, they may not be sufficient, so in case you find other
3332change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
3333mail</a>:</p>
3334<ol>
3335 <li>The package name have changed from libxml to libxml2, the library name
3336 is now -lxml2 . There is a new xml2-config script which should be used to
3337 select the right parameters libxml2</li>
3338 <li>Node <strong>childs</strong> field has been renamed
3339 <strong>children</strong> so s/childs/children/g should be applied
3340 (probablility of having "childs" anywere else is close to 0+</li>
3341 <li>The document don't have anymore a <strong>root</strong> element it has
3342 been replaced by <strong>children</strong> and usually you will get a
3343 list of element here. For example a Dtd element for the internal subset
3344 and it's declaration may be found in that list, as well as processing
3345 instructions or comments found before or after the document root element.
3346 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
3347 a document. Alternatively if you are sure to not reference Dtds nor have
3348 PIs or comments before or after the root element
3349 s/-&gt;root/-&gt;children/g will probably do it.</li>
3350 <li>The white space issue, this one is more complex, unless special case of
3351 validating parsing, the line breaks and spaces usually used for indenting
3352 and formatting the document content becomes significant. So they are
3353 reported by SAX and if your using the DOM tree, corresponding nodes are
3354 generated. Too approach can be taken:
3355 <ol>
3356 <li>lazy one, use the compatibility call
3357 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
3358 relying on a special (and possibly broken) set of heuristics of
3359 libxml to detect ignorable blanks. Don't complain if it breaks or
3360 make your application not 100% clean w.r.t. to it's input.</li>
3361 <li>the Right Way: change you code to accept possibly unsignificant
3362 blanks characters, or have your tree populated with weird blank text
3363 nodes. You can spot them using the comodity function
3364 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
3365 nodes.</li>
3366 </ol>
3367 <p>Note also that with the new default the output functions don't add any
3368 extra indentation when saving a tree in order to be able to round trip
3369 (read and save) without inflating the document with extra formatting
3370 chars.</p>
3371 </li>
3372 <li>The include path has changed to $prefix/libxml/ and the includes
3373 themselves uses this new prefix in includes instructions... If you are
3374 using (as expected) the
3375 <pre>xml2-config --cflags</pre>
3376 <p>output to generate you compile commands this will probably work out of
3377 the box</p>
3378 </li>
3379 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
3380 byte of the head of the document available for character detection.</li>
3381</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3382
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3383<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3384
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3385<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3386to allow smoth upgrade of existing libxml v1code while retaining
3387compatibility. They offers the following:</p>
3388<ol>
3389 <li>similar include naming, one should use
3390 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3391 <li>similar identifiers defined via macros for the child and root fields:
3392 respectively <strong>xmlChildrenNode</strong> and
3393 <strong>xmlRootNode</strong></li>
3394 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3395 inserted once in the client code</li>
3396</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3397
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3398<p>So the roadmap to upgrade your existing libxml applications is the
3399following:</p>
3400<ol>
3401 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3402 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3403 used and change it to <strong>xmlRootNode</strong></li>
3404 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3405 field is used and change it to <strong>xmlChildrenNode</strong></li>
3406 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3407 <strong>main()</strong> or in the library init entry point</li>
3408 <li>Recompile, check compatibility, it should still work</li>
3409 <li>Change your configure script to look first for xml2-config and fallback
3410 using xml-config . Use the --cflags and --libs ouptut of the command as
3411 the Include and Linking parameters needed to use libxml.</li>
3412 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3413 libxml-devel-1.8.y can be kept simultaneously)</li>
3414 <li>remove your config.cache, relaunch your configuration mechanism, and
3415 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3416 <li>Test that your application is still running correctly, if not this may
3417 be due to extra empty nodes due to formating spaces being kept in libxml2
3418 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3419 code before calling the parser (next to
3420 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3421</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3422
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3423<p>Following those steps should work. It worked for some of my own code.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3424
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3425<p>Let me put some emphasis on the fact that there is far more changes from
3426libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3427has been considerably cleaned up and the conformance to the XML specification
3428has been drastically improved too. Don't take those changes as an excuse to
3429not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3430
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3431<h2><a name="Thread">Thread safety</a></h2>
3432
3433<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3434threads can safely work in parallel parsing different documents. There is
3435however a couple of things to do to ensure it:</p>
3436<ul>
3437 <li>configure the library accordingly using the --with-threads options</li>
3438 <li>call xmlInitParser() in the "main" thread before using any of the
3439 libxml API (except possibly selecting a different memory allocator)</li>
3440</ul>
3441
3442<p>Note that the thread safety cannot be ensured for multiple threads sharing
3443the same document, the locking must be done at the application level, libxml
3444exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3445The parts of the library checked for thread safety are:</p>
3446<ul>
3447 <li>concurrent loading</li>
3448 <li>file access resolution</li>
3449 <li>catalog access</li>
3450 <li>catalog building</li>
3451 <li>entities lookup/accesses</li>
3452 <li>validation</li>
3453 <li>global variables per-thread override</li>
3454 <li>memory handling</li>
3455</ul>
3456
3457<p>XPath is supposed to be thread safe now, but this wasn't tested
3458seriously.</p>
3459
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3460<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3461
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3462<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3463Object Model</em>; this is an API for accessing XML or HTML structured
3464documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3465and will be based on gnome-xml. This will be a far cleaner interface to
3466manipulate XML files within Gnome since it won't expose the internal
3467structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3468
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3469<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3470href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3471is a full DOM interface, thanks to Paolo Casarini, check the <a
3472href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3473informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3474
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3475<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3476
3477<p>Here is a real size example, where the actual content of the application
3478data is not kept in the DOM tree but uses internal structures. It is based on
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3479a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3480storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3481base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3482<pre>&lt;?xml version="1.0"?&gt;
3483&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3484 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3485
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3486 &lt;gjob:Job&gt;
3487 &lt;gjob:Project ID="3"/&gt;
3488 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3489 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3490
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3491 &lt;gjob:Update&gt;
3492 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3493 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3494 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3495 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3496
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3497 &lt;gjob:Developers&gt;
3498 &lt;gjob:Developer&gt;
3499 &lt;/gjob:Developer&gt;
3500 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3501
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3502 &lt;gjob:Contact&gt;
3503 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3504 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3505 &lt;gjob:Company&gt;
3506 &lt;/gjob:Company&gt;
3507 &lt;gjob:Organisation&gt;
3508 &lt;/gjob:Organisation&gt;
3509 &lt;gjob:Webpage&gt;
3510 &lt;/gjob:Webpage&gt;
3511 &lt;gjob:Snailmail&gt;
3512 &lt;/gjob:Snailmail&gt;
3513 &lt;gjob:Phone&gt;
3514 &lt;/gjob:Phone&gt;
3515 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3516
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3517 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3518 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3519 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3520
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3521 &lt;gjob:Skills&gt;
3522 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3523
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3524 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3525 A GNOME based system that will allow a superuser to configure
3526 compressed and uncompressed files and/or file systems to be backed
3527 up with a supported media in the system. This should be able to
3528 perform via find commands generating a list of files that are passed
3529 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3530 or via operations performed on the filesystem itself. Email
3531 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3532 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3533
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3534 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3535
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3536 &lt;/gjob:Jobs&gt;
3537&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3538
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3539<p>While loading the XML file into an internal DOM tree is a matter of
3540calling only a couple of functions, browsing the tree to gather the ata and
3541generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3542
3543<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3544structure. For example, the ordering of the attributes is not significant,
3545the XML specification is clear about it. It's also usually a good idea not to
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3546depend on the order of the children of a given node, unless it really makes
3547things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3548<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3549 * A person record
3550 */
3551typedef struct person {
3552 char *name;
3553 char *email;
3554 char *company;
3555 char *organisation;
3556 char *smail;
3557 char *webPage;
3558 char *phone;
3559} person, *personPtr;
3560
3561/*
3562 * And the code needed to parse it
3563 */
3564personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3565 personPtr ret = NULL;
3566
3567DEBUG("parsePerson\n");
3568 /*
3569 * allocate the struct
3570 */
3571 ret = (personPtr) malloc(sizeof(person));
3572 if (ret == NULL) {
3573 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3574 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3575 }
3576 memset(ret, 0, sizeof(person));
3577
3578 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3579 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3580 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3581 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3582 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3583 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3584 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3585 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3586 }
3587
3588 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3589}</pre>
3590
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3591<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3592<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3593 <li>Usually a recursive parsing style is the more convenient one: XML data
3594 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3595 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3596 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3597 i.e. the pointer to the global XML document and the namespace reserved to
3598 the application. Document wide information are needed for example to
3599 decode entities and it's a good coding practice to define a namespace for
3600 your application set of data and test that the element and attributes
3601 you're analyzing actually pertains to your application space. This is
3602 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3603 <li>To retrieve text and attributes value, you can use the function
3604 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3605 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3606</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3607
3608<p>Here is another piece of code used to parse another level of the
3609structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3610<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3611/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3612 * a Description for a Job
3613 */
3614typedef struct job {
3615 char *projectID;
3616 char *application;
3617 char *category;
3618 personPtr contact;
3619 int nbDevelopers;
3620 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3621} job, *jobPtr;
3622
3623/*
3624 * And the code needed to parse it
3625 */
3626jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3627 jobPtr ret = NULL;
3628
3629DEBUG("parseJob\n");
3630 /*
3631 * allocate the struct
3632 */
3633 ret = (jobPtr) malloc(sizeof(job));
3634 if (ret == NULL) {
3635 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3636 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3637 }
3638 memset(ret, 0, sizeof(job));
3639
3640 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3641 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3642 while (cur != NULL) {
3643
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3644 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3645 ret-&gt;projectID = xmlGetProp(cur, "ID");
3646 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3647 fprintf(stderr, "Project has no ID\n");
3648 }
3649 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3650 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3651 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3652 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3653 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3654 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3655 ret-&gt;contact = parsePerson(doc, ns, cur);
3656 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3657 }
3658
3659 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3660}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3661
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3662<p>Once you are used to it, writing this kind of code is quite simple, but
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3663boring. Ultimately, it could be possble to write stubbers taking either C
3664data structure definitions, a set of XML examples or an XML DTD and produce
3665the code needed to import and export the content between C data and XML
3666storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3667
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3668<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3669parsing example</a> as a template, it is also available with Makefile in the
3670Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3671
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3672<h2><a name="Contributi">Contributions</a></h2>
3673<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3674 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3675 patches, Gary Pennington worked on the validation API, threading support
3676 and Solaris port.</li>
3677 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3678 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
3679 for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3680 Website: <a
3681 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3682 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3683 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3684 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the
3685 maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3686 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3687 provides binaries</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3688 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides
3689 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3690 <li><a
3691 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3692 Sergeant</a> developped <a
3693 href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
3694 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
3695 application server</a></li>
3696 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a
3697 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3698 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3699 documentation</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3700 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
3701 href="http://xmlsoft.org/messages/0488.html">man pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3702 <li>there is a module for <a
3703 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3704 in OpenNSD/AOLServer</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]3705 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provided the
3706 first version of libxml/libxslt <a
3707 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]3708 <li>Petr Kozelka provides <a
3709 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
3710 libxml2</a> with Kylix and Delphi and other Pascal compilers</li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]3711 <li><a href="mailto:aleksey@aleksey.com">Aleksey Sanin</a> implemented the
3712 <a href="http://www.w3.org/Signature/">XML Canonicalization and XML
3713 Digital Signature</a> <a
3714 href="http://www.aleksey.com/xmlsec/">implementations for libxml2</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3715</ul>
3716
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3717<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3718</body>
3719</html>