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blob: 7e04f03d71ecb9b5f3a02f0e4c846ca96d9bb2d3 [file] [log] [blame]
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
24markup language.</p>
25
26<p>Libxml2 implements a number of existing standards related to markup
27languages:</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]28<ul>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]29 <li>the XML standard: <a
30 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li>
31 <li>Namespaces in XML: <a
32 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li>
33 <li>XML Base: <a
34 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]35 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a> :
36 Uniform Resource Identifiers <a
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]37 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li>
38 <li>XML Path Language (XPath) 1.0: <a
39 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li>
40 <li>HTML4 parser: <a
41 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li>
42 <li>most of XML Pointer Language (XPointer) Version 1.0: <a
43 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li>
44 <li>XML Inclusions (XInclude) Version 1.0: <a
45 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li>
46 <li>[ISO-8859-1], <a
47 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8]
48 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a>
49 [UTF-16] core encodings</li>
50 <li>part of SGML Open Technical Resolution TR9401:1997</li>
51 <li>XML Catalogs Working Draft 06 August 2001: <a
52 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^]53 <li>Canonical XML Version 1.0: <a
54 href="http://www.w3.org/TR/xml-c14n">http://www.w3.org/TR/xml-c14n</a>
55 and the
56 <p>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></p>
58 </li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]59</ul>
60
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]61<p>In most cases libxml tries to implement the specifications in a relatively
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]62strict way. As of release 2.4.16, libxml2 passes all 1800+ tests from the <a
63href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests
64Suite</a>.</p>
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]65
66<p>To some extent libxml2 provide some support for the following other
67specification but don't claim to implement them:</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]68<ul>
69 <li>Document Object Model (DOM) <a
70 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
71 it doesn't implement the API itself, gdome2 does this in top of
72 libxml2</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]73 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a> :
74 libxml implements a basic FTP client code</li>
75 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a> :
76 HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]77 <li>SAX: a minimal SAX implementation compatible with early expat
78 versions</li>
79 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
80 XML</li>
81</ul>
82
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]83<p>Libxml2 is known to be very portable, should build and work without
84serious troubles on a variety of systems (Linux, Unix, Windows, CygWin,
85MacOs, MacOsX, RISC Os, OS/2, VMS, QNX, MVS, ...)</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]86
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]87<p>Separate documents:</p>
88<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]89 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a> providing an
90 implementation of XSLT 1.0 and extensions on top of 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 Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]92 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]93</ul>
94
95<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]96
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]97<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]98href="http://www.w3.org/XML/">XML</a> C library developped for the <a
99href="http://www.gnome.org/">Gnome</a> project. <a
100href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
101structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]102
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]103<p>Here are some key points about libxml:</p>
104<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]105 <li>Libxml exports Push and Pull type parser interfaces for both XML and
106 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]107 <li>Libxml can do DTD validation at parse time, using a parsed document
108 instance, or with an arbitrary DTD.</li>
109 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]110 href="http://www.w3.org/TR/xpath">XPath</a>, <a
111 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
112 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]113 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]114 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]115 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]116 <li>Basic support for HTTP and FTP client allowing aplications to fetch
117 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]118 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]119 <li>The internal document repesentation is as close as possible to the <a
120 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
121 <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]122 like interface</a>; the interface is designed to be compatible with <a
123 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]124 <li>This library is released under the <a
125 href="http://www.opensource.org/licenses/mit-license.html">MIT
126 Licence</a> see the Copyright file in the distribution for the precise
127 wording.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]128</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]129
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]130<p>Warning: unless you are forced to because your application links with a
131Gnome library requiring it, <strong><span
132style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
133libxml2</p>
134
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]135<h2><a name="FAQ">FAQ</a></h2>
136
137<p>Table of Content:</p>
138<ul>
139 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
140 <li><a href="FAQ.html#Installati">Installation</a></li>
141 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
142 <li><a href="FAQ.html#Developer">Developer corner</a></li>
143</ul>
144
145<h3><a name="Licence">Licence</a>(s)</h3>
146<ol>
147 <li><em>Licensing Terms for libxml</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]148 <p>libxml is released under the <a
149 href="http://www.opensource.org/licenses/mit-license.html">MIT
150 Licence</a>, see the file Copyright in the distribution for the precise
151 wording</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]152 </li>
153 <li><em>Can I embed libxml in a proprietary application ?</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]154 <p>Yes. The MIT Licence allows you to also keep proprietary the changes
155 you made to libxml, but it would be graceful to provide back bugfixes and
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]156 improvements as patches for possible incorporation in the main
157 development tree</p>
158 </li>
159</ol>
160
161<h3><a name="Installati">Installation</a></h3>
162<ol>
163 <li>Unless you are forced to because your application links with a Gnome
164 library requiring it, <strong><span style="background-color: #FF0000">Do
165 Not Use libxml1</span></strong>, use libxml2</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]166 <li><em>Where can I get libxml</em> ?
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]167 <p>The original distribution comes from <a
168 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
169 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
170 <p>Most linux and Bsd distribution includes libxml, this is probably the
171 safer way for end-users</p>
172 <p>David Doolin provides precompiled Windows versions at <a
173 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
174 </li>
175 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
176 <ul>
177 <li>If you are not concerned by any existing backward compatibility
178 with existing application, install libxml2 only</li>
179 <li>If you are not doing development, you can safely install both.
180 usually the packages <a
181 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
182 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
183 compatible (this is not the case for development packages)</li>
184 <li>If you are a developer and your system provides separate packaging
185 for shared libraries and the development components, it is possible
186 to install libxml and libxml2, and also <a
187 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
188 and <a
189 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
190 too for libxml2 &gt;= 2.3.0</li>
191 <li>If you are developing a new application, please develop against
192 libxml2(-devel)</li>
193 </ul>
194 </li>
195 <li><em>I can't install the libxml package it conflicts with libxml0</em>
196 <p>You probably have an old libxml0 package used to provide the shared
197 library for libxml.so.0, you can probably safely remove it. Anyway the
198 libxml packages provided on <a
199 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
200 libxml.so.0</p>
201 </li>
202 <li><em>I can't install the libxml(2) RPM package due to failed
203 dependancies</em>
204 <p>The most generic solution is to refetch the latest src.rpm , and
205 rebuild it locally with</p>
206 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
207 <p>if everything goes well it will generate two binary rpm (one providing
208 the shared libs and xmllint, and the other one, the -devel package
209 providing includes, static libraries and scripts needed to build
210 applications with libxml(2)) that you can install locally.</p>
211 </li>
212</ol>
213
214<h3><a name="Compilatio">Compilation</a></h3>
215<ol>
216 <li><em>What is the process to compile libxml ?</em>
217 <p>As most UNIX libraries libxml follows the "standard":</p>
218 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
219 <p><code>cd libxml-xxxx</code></p>
220 <p><code>./configure --help</code></p>
221 <p>to see the options, then the compilation/installation proper</p>
222 <p><code>./configure [possible options]</code></p>
223 <p><code>make</code></p>
224 <p><code>make install</code></p>
225 <p>At that point you may have to rerun ldconfig or similar utility to
226 update your list of installed shared libs.</p>
227 </li>
228 <li><em>What other libraries are needed to compile/install libxml ?</em>
229 <p>Libxml does not requires any other library, the normal C ANSI API
230 should be sufficient (please report any violation to this rule you may
231 find).</p>
232 <p>However if found at configuration time libxml will detect and use the
233 following libs:</p>
234 <ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]235 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a
236 highly portable and available widely compression library</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]237 <li>iconv: a powerful character encoding conversion library. It's
238 included by default on recent glibc libraries, so it doesn't need to
239 be installed specifically on linux. It seems it's now <a
240 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
241 of the official UNIX</a> specification. Here is one <a
242 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
243 of the library</a> which source can be found <a
244 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
245 </ul>
246 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]247 <li><em>make check fails on some platforms</em>
248 <p>Sometime the regression tests results don't completely match the value
249 produced by the parser, and the makefile uses diff to print the delta. On
250 some platforms the diff return breaks the compilation process, if the
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]251 diff is small this is probably not a serious problem.</p>
252 <p>Sometimes (especially on Solaris) make checks fails due to limitations
253 in make. Try using GNU-make instead.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]254 </li>
255 <li><em>I use the CVS version and there is no configure script</em>
256 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
257 script to regenerate the configure and Makefiles, like:</p>
258 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
259 </li>
260 <li><em>I have troubles when running make tests with gcc-3.0</em>
261 <p>It seems the initial release of gcc-3.0 has a problem with the
262 optimizer which miscompiles the URI module. Please use another
263 compiler</p>
264 </li>
265</ol>
266
267<h3><a name="Developer">Developer</a> corner</h3>
268<ol>
269 <li><em>xmlDocDump() generates output on one line</em>
270 <p>libxml will not <strong>invent</strong> spaces in the content of a
271 document since <strong>all spaces in the content of a document are
272 significant</strong>. If you build a tree from the API and want
273 indentation:</p>
274 <ol>
275 <li>the correct way is to generate those yourself too</li>
276 <li>the dangerous way is to ask libxml to add those blanks to your
277 content <strong>modifying the content of your document in the
278 process</strong>. The result may not be what you expect. There is
279 <strong>NO</strong> way to guarantee that such a modification won't
280 impact other part of the content of your document. See <a
281 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
282 ()</a> and <a
283 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
284 ()</a></li>
285 </ol>
286 </li>
287 <li>Extra nodes in the document:
288 <p><em>For a XML file as below:</em></p>
289 <pre>&lt;?xml version="1.0"?&gt;
290&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
291&lt;NODE CommFlag="0"/&gt;
292&lt;NODE CommFlag="1"/&gt;
293&lt;/PLAN&gt;</pre>
294 <p><em>after parsing it with the function
295 pxmlDoc=xmlParseFile(...);</em></p>
296 <p><em>I want to the get the content of the first node (node with the
297 CommFlag="0")</em></p>
298 <p><em>so I did it as following;</em></p>
299 <pre>xmlNodePtr pode;
300pnode=pxmlDoc-&gt;children-&gt;children;</pre>
301 <p><em>but it does not work. If I change it to</em></p>
302 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
303 <p><em>then it works. Can someone explain it to me.</em></p>
304 <p></p>
305 <p>In XML all characters in the content of the document are significant
306 <strong>including blanks and formatting line breaks</strong>.</p>
307 <p>The extra nodes you are wondering about are just that, text nodes with
308 the formatting spaces wich are part of the document but that people tend
309 to forget. There is a function <a
310 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
311 ()</a> to remove those at parse time, but that's an heuristic, and its
312 use should be limited to case where you are sure there is no
313 mixed-content in the document.</p>
314 </li>
315 <li><em>I get compilation errors of existing code like when accessing
316 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
317 <p>You are compiling code developed for libxml version 1 and using a
318 libxml2 development environment. Either switch back to libxml v1 devel or
319 even better fix the code to compile with libxml2 (or both) by <a
320 href="upgrade.html">following the instructions</a>.</p>
321 </li>
322 <li><em>I get compilation errors about non existing
323 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
324 fields</em>
325 <p>The source code you are using has been <a
326 href="upgrade.html">upgraded</a> to be able to compile with both libxml
327 and libxml2, but you need to install a more recent version:
328 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
329 </li>
330 <li><em>XPath implementation looks seriously broken</em>
331 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
332 a recent version, the implementation and debug of libxslt generated fixes
333 for most obvious problems.</p>
334 </li>
335 <li><em>The example provided in the web page does not compile</em>
336 <p>It's hard to maintain the documentation in sync with the code
337 &lt;grin/&gt; ...</p>
338 <p>Check the previous points 1/ and 2/ raised before, and send
339 patches.</p>
340 </li>
341 <li><em>Where can I get more examples and informations than in the web
342 page</em>
343 <p>Ideally a libxml book would be nice. I have no such plan ... But you
344 can:</p>
345 <ul>
346 <li>check more deeply the <a href="html/libxml-lib.html">existing
347 generated doc</a></li>
348 <li>looks for examples of use for libxml function using the Gnome code
349 for example the following will query the full Gnome CVs base for the
350 use of the <strong>xmlAddChild()</strong> function:
351 <p><a
352 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
353 <p>This may be slow, a large hardware donation to the gnome project
354 could cure this :-)</p>
355 </li>
356 <li><a
357 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]358 the libxml source</a> , I try to write code as clean and documented
359 as possible, so looking at it may be helpful</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]360 </ul>
361 </li>
362 <li>What about C++ ?
363 <p>libxml is written in pure C in order to allow easy reuse on a number
364 of platforms, including embedded systems. I don't intend to convert to
365 C++.</p>
366 <p>There is however a C++ wrapper provided by Ari Johnson
367 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
368 <p>Website: <a
369 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
370 <p>Download: <a
371 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
372 </li>
373 <li>How to validate a document a posteriori ?
374 <p>It is possible to validate documents which had not been validated at
375 initial parsing time or documents who have been built from scratch using
376 the API. Use the <a
377 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
378 function. It is also possible to simply add a Dtd to an existing
379 document:</p>
380 <pre>xmlDocPtr doc; /* your existing document */
381 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
382 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
383
384 doc-&gt;intSubset = dtd;
385 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
386 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
387 </pre>
388 </li>
389 <li>etc ...</li>
390</ol>
391
392<p></p>
393
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]394<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]395
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]396<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]397<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]398 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]399 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]400 documentation</a> automatically extracted from code comments (using <a
401 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
402 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]403 <li>Look at the documentation about <a href="encoding.html">libxml
404 internationalization support</a></li>
Daniel Veillardbc66f852002-01-14 09:49:20 +0000[diff] [blame]405 <li>This page provides a global overview and <a href="example.html">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]406 examples</a> on how to use libxml.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]407 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]408 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
409 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]410 <li>George Lebl wrote <a
411 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]412 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]413 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
414 file</a></li>
415 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
416 starting a new project using libxml you should really use the 2.x
417 version.</li>
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]418 <li>And don't forget to look at the <a
419 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]420</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]421
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]422<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]423
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]424<p>Well, bugs or missing features are always possible, and I will make a
425point of fixing them in a timely fashion. The best way to report a bug is to
426use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
427bug tracking database</a> (make sure to use the "libxml" module name). I look
428at 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]429still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]430
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]431<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]432href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
433href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]434href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
435please visit the <a
436href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
437follow the instructions. <strong>Do not send code, I won't debug it</strong>
438(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]439
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]440<p>Check the following <strong><span style="color: #FF0000">before
441posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]442<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]443 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]444 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
445 version</a>, and that the problem still shows up in those</li>
446 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
447 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]448 there is probably a fix available, similary check the <a
449 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]450 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]451 <li>make sure you can reproduce the bug with xmllint or one of the test
452 programs found in source in the distribution</li>
453 <li>Please send the command showing the error as well as the input (as an
454 attachement)</li>
455</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]456
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]457<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]458href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]459related I will approve it.. Please do not send me mail directly, it makes
460things really harder to track and in some cases I'm not the best person to
461answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]462
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]463<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]464probably be processed faster.</p>
465
466<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]467href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]468provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]469questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]470documentantion</a> is not as polished as I would like (i need to learn more
471about Docbook), but it's a good starting point.</p>
472
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]473<h2><a name="help">How to help</a></h2>
474
475<p>You can help the project in various ways, the best thing to do first is to
476subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]477href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
478href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]479database:</a>:</p>
480<ol>
481 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]482 <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]483 be integrated in all cases but help pinpointing portability problems
484 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]485 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]486 as HTML diffs).</li>
487 <li>provide new documentations pieces (translations, examples, etc ...)</li>
488 <li>Check the TODO file and try to close one of the items</li>
489 <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]490 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
491 </a>before to avoid synchronization problems and check that the suggested
492 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]493</ol>
494
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]495<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]496
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]497<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]498href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
499href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
500href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]501href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]502as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]503archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]504href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
505packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]506href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
507href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]508packages installed to compile applications using libxml.) <a
509href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
510of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]511href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]512provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]513Pennington</a> provides <a href="http://garypennington.net/libxml2/">Solaris
514binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]515
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]516<p><a name="Snapshot">Snapshot:</a></p>
517<ul>
518 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]519 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]520 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]521 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]522</ul>
523
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]524<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]525
526<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]527platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]528languages have been provided, and can be found in the <a
529href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]530
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]531<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]532<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]533 <li><p>The <a
534 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]535 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]536 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
537 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]538 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]539 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]540</ul>
541
542<h2><a name="News">News</a></h2>
543
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]544<h3>CVS only : check the <a
545href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]546for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]547
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]548<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]549you want to test those</p>
550<ul>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]551 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
552 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]553</ul>
554
555<h3>2.4.17: Mar 8 2002</h3>
556<ul>
557 <li>a lot of bug fixes, including "namespace nodes have no parents in
558 XPath"</li>
559 <li>fixed/improved the Python wrappers, added more examples and more
560 regression tests, XPath extension functions can now return node-sets</li>
561 <li>added the XML Canonalization support from Aleksey Sanin</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]562</ul>
563
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]564<h3>2.4.16: Feb 20 2002</h3>
565<ul>
566 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite
567 from OASIS and W3C. Compliance has been significantly improved.</li>
568 <li>a couple of portability fixes too.</li>
569</ul>
570
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]571<h3>2.4.15: Feb 11 2002</h3>
572<ul>
573 <li>Fixed the Makefiles, especially the python module ones</li>
574 <li>A few bug fixes and cleanup</li>
575 <li>Includes cleanup</li>
576</ul>
577
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]578<h3>2.4.14: Feb 8 2002</h3>
579<ul>
580 <li>Change of Licence to the <a
581 href="http://www.opensource.org/licenses/mit-license.html">MIT
582 Licence</a> basisally for integration in XFree86 codebase, and removing
583 confusion around the previous dual-licencing</li>
584 <li>added Python bindings, beta software but should already be quite
585 complete</li>
586 <li>a large number of fixes and cleanups, especially for all tree
587 manipulations</li>
588 <li>cleanup of the headers, generation of a reference API definition in
589 XML</li>
590</ul>
591
592<h3>2.4.13: Jan 14 2002</h3>
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]593<ul>
594 <li>update of the documentation: John Fleck and Charlie Bozeman</li>
595 <li>cleanup of timing code from Justin Fletcher</li>
596 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei
597 Narojnyi</li>
598 <li>Cygwin patch from Robert Collins</li>
599 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li>
600</ul>
601
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]602<h3>2.4.12: Dec 7 2001</h3>
603<ul>
604 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman),
605 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups
606 (robert)</li>
607 <li>Eric Lavigne contributed project files for MacOS</li>
608 <li>some makefiles cleanups</li>
609</ul>
610
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]611<h3>2.4.11: Nov 26 2001</h3>
612<ul>
613 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
614 cleanups</li>
615 <li>xmllint man pages improvement by Heiko Rupp</li>
616 <li>updated VMS build instructions from John A Fotheringham</li>
617 <li>Windows Makefiles updates from Igor</li>
618</ul>
619
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]620<h3>2.4.10: Nov 10 2001</h3>
621<ul>
622 <li>URI escaping fix (Joel Young)</li>
623 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
624 <li>Fixes namespace handling problems when using DTD and validation</li>
625 <li>improvements on xmllint: Morus Walter patches for --format and
626 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
627 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
628 <li>fixes to the HTML parser</li>
629</ul>
630
631<h3>2.4.9: Nov 6 2001</h3>
632<ul>
633 <li>fixes more catalog bugs</li>
634 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
635</ul>
636
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]637<h3>2.4.8: Nov 4 2001</h3>
638<ul>
639 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
640 tool</li>
641 <li>fixed a compile errors and some includes troubles.</li>
642</ul>
643
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]644<h3>2.4.7: Oct 30 2001</h3>
645<ul>
646 <li>exported some debugging interfaces</li>
647 <li>serious rewrite of the catalog code</li>
648 <li>integrated Gary Pennington thread safety patch, added configure option
649 and regression tests</li>
650 <li>removed an HTML parser bug</li>
651 <li>fixed a couple of potentially serious validation bugs</li>
652 <li>integrated the SGML DocBook support in xmllint</li>
653 <li>changed the nanoftp anonymous login passwd</li>
654 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
655 <li>general bug fixes</li>
656 <li>updated xmllint man page by John Fleck</li>
657 <li>some VMS and Windows updates</li>
658</ul>
659
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]660<h3>2.4.6: Oct 10 2001</h3>
661<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]662 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]663 <li>portability and configure fixes</li>
664 <li>an infinite loop on the HTML parser was removed (William)</li>
665 <li>Windows makefile patches from Igor</li>
666 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
667 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
668</ul>
669
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]670<h3>2.4.5: Sep 14 2001</h3>
671<ul>
672 <li>Remove a few annoying bugs in 2.4.4</li>
673 <li>forces the HTML serializer to output decimal charrefs since some
674 version of Netscape can't handle hexadecimal ones</li>
675</ul>
676
677<h3>1.8.16: Sep 14 2001</h3>
678<ul>
679 <li>maintenance release of the old libxml1 branch, couple of bug and
680 portability fixes</li>
681</ul>
682
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]683<h3>2.4.4: Sep 12 2001</h3>
684<ul>
685 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
686 Catalog</li>
687 <li>a few bug fixes and some portability changes</li>
688 <li>some documentation cleanups</li>
689</ul>
690
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]691<h3>2.4.3: Aug 23 2001</h3>
692<ul>
693 <li>XML Catalog support see the doc</li>
694 <li>New NaN/Infinity floating point code</li>
695 <li>A few bug fixes</li>
696</ul>
697
698<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]699<ul>
700 <li>adds xmlLineNumbersDefault() to control line number generation</li>
701 <li>lot of bug fixes</li>
702 <li>the Microsoft MSC projects files shuld now be up to date</li>
703 <li>inheritance of namespaces from DTD defaulted attributes</li>
704 <li>fixes a serious potential security bug</li>
705 <li>added a --format option to xmllint</li>
706</ul>
707
708<h3>2.4.1: July 24 2001</h3>
709<ul>
710 <li>possibility to keep line numbers in the tree</li>
711 <li>some computation NaN fixes</li>
712 <li>extension of the XPath API</li>
713 <li>cleanup for alpha and ia64 targets</li>
714 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]715</ul>
716
717<h3>2.4.0: July 10 2001</h3>
718<ul>
719 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
720 <li>Fixed XML Base implementation, added a coupel of examples to the
721 regression tests</li>
722 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]723</ul>
724
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]725<h3>2.3.14: July 5 2001</h3>
726<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]727 <li>fixed some entities problems and reduce mem requirement when
728 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]729 <li>lots of improvements in the XPath queries interpreter can be
730 substancially faster</li>
731 <li>Makefiles and configure cleanups</li>
732 <li>Fixes to XPath variable eval, and compare on empty node set</li>
733 <li>HTML tag closing bug fixed</li>
734 <li>Fixed an URI reference computating problem when validating</li>
735</ul>
736
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]737<h3>2.3.13: June 28 2001</h3>
738<ul>
739 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
740 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
741</ul>
742
743<h3>1.8.14: June 28 2001</h3>
744<ul>
745 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
746 <li>Small Makefile fix</li>
747</ul>
748
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]749<h3>2.3.12: June 26 2001</h3>
750<ul>
751 <li>lots of cleanup</li>
752 <li>a couple of validation fix</li>
753 <li>fixed line number counting</li>
754 <li>fixed serious problems in the XInclude processing</li>
755 <li>added support for UTF8 BOM at beginning of entities</li>
756 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
757 miscompile uri.c (William), Thomas Leitner provided a fix for the
758 optimizer on Tru64</li>
759 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
760 compilation on Windows MSC</li>
761 <li>update of libxml-doc.el (Felix Natter)</li>
762 <li>fixed 2 bugs in URI normalization code</li>
763</ul>
764
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]765<h3>2.3.11: June 17 2001</h3>
766<ul>
767 <li>updates to trio, Makefiles and configure should fix some portability
768 problems (alpha)</li>
769 <li>fixed some HTML serialization problems (pre, script, and block/inline
770 handling), added encoding aware APIs, cleanup of this code</li>
771 <li>added xmlHasNsProp()</li>
772 <li>implemented a specific PI for encoding support in the DocBook SGML
773 parser</li>
774 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
775 node selection)</li>
776 <li>fixed a performance problem and an error in the validation code</li>
777 <li>fixed XInclude routine to implement the recursive behaviour</li>
778 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
779 <li>added --version to xmllint for bug reports</li>
780</ul>
781
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]782<h3>2.3.10: June 1 2001</h3>
783<ul>
784 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]785 <li>a number of reported bugs got fixed, in XPath, iconv detection,
786 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]787 <li>XPath string function should now handle unicode correctly</li>
788</ul>
789
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]790<h3>2.3.9: May 19 2001</h3>
791
792<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
793<ul>
794 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
795 <li>some serious speed optimisation again</li>
796 <li>some documentation cleanups</li>
797 <li>trying to get better linking on solaris (-R)</li>
798 <li>XPath API cleanup from Thomas Broyer</li>
799 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
800 xmlValidGetValidElements()</li>
801 <li>Added an INSTALL file</li>
802 <li>Attribute removal added to API: #54433</li>
803 <li>added a basic support for SGML catalogs</li>
804 <li>fixed xmlKeepBlanksDefault(0) API</li>
805 <li>bugfix in xmlNodeGetLang()</li>
806 <li>fixed a small configure portability problem</li>
807 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
808</ul>
809
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]810<h3>1.8.13: May 14 2001</h3>
811<ul>
812 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
813</ul>
814
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]815<h3>2.3.8: May 3 2001</h3>
816<ul>
817 <li>Integrated an SGML DocBook parser for the Gnome project</li>
818 <li>Fixed a few things in the HTML parser</li>
819 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
820 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]821 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
822 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]823 <li>incorporated more Windows cleanup</li>
824 <li>added xmlSaveFormatFile()</li>
825 <li>fixed problems in copying nodes with entities references (gdome)</li>
826 <li>removed some troubles surrounding the new validation module</li>
827</ul>
828
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]829<h3>2.3.7: April 22 2001</h3>
830<ul>
831 <li>lots of small bug fixes, corrected XPointer</li>
832 <li>Non determinist content model validation support</li>
833 <li>added xmlDocCopyNode for gdome2</li>
834 <li>revamped the way the HTML parser handles end of tags</li>
835 <li>XPath: corrctions of namespacessupport and number formatting</li>
836 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
837 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
838 <li>Improved validation speed sensible for DocBook</li>
839 <li>fixed a big bug with ID declared in external parsed entities</li>
840 <li>portability fixes, update of Trio from Bjorn Reese</li>
841</ul>
842
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]843<h3>2.3.6: April 8 2001</h3>
844<ul>
845 <li>Code cleanup using extreme gcc compiler warning options, found and
846 cleared half a dozen potential problem</li>
847 <li>the Eazel team found an XML parser bug</li>
848 <li>cleaned up the user of some of the string formatting function. used the
849 trio library code to provide the one needed when the platform is missing
850 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]851 <li>xpath: removed a memory leak and fixed the predicate evaluation
852 problem, extended the testsuite and cleaned up the result. XPointer seems
853 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]854</ul>
855
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]856<h3>2.3.5: Mar 23 2001</h3>
857<ul>
858 <li>Biggest change is separate parsing and evaluation of XPath expressions,
859 there is some new APIs for this too</li>
860 <li>included a number of bug fixes(XML push parser, 51876, notations,
861 52299)</li>
862 <li>Fixed some portability issues</li>
863</ul>
864
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]865<h3>2.3.4: Mar 10 2001</h3>
866<ul>
867 <li>Fixed bugs #51860 and #51861</li>
868 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
869 size to be application tunable.</li>
870 <li>Some cleanup in the validation code, still a bug left and this part
871 should probably be rewritten to support ambiguous content model :-\</li>
872 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
873 parser</li>
874 <li>Fixed another bug in xmlNodeGetContent()</li>
875 <li>Bjorn fixed XPath node collection and Number formatting</li>
876 <li>Fixed a loop reported in the HTML parsing</li>
877 <li>blank space are reported even if the Dtd content model proves that they
878 are formatting spaces, this is for XmL conformance</li>
879</ul>
880
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]881<h3>2.3.3: Mar 1 2001</h3>
882<ul>
883 <li>small change in XPath for XSLT</li>
884 <li>documentation cleanups</li>
885 <li>fix in validation by Gary Pennington</li>
886 <li>serious parsing performances improvements</li>
887</ul>
888
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]889<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]890<ul>
891 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
892 <li>fixed a Dtd parsing bug</li>
893 <li>fixed a bug in xmlNodeGetContent</li>
894 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
895</ul>
896
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]897<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]898<ul>
899 <li>some XPath and HTML bug fixes for XSLT</li>
900 <li>small extension of the hash table interfaces for DOM gdome2
901 implementation</li>
902 <li>A few bug fixes</li>
903</ul>
904
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]905<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]906<ul>
907 <li>Lots of XPath bug fixes</li>
908 <li>Add a mode with Dtd lookup but without validation error reporting for
909 XSLT</li>
910 <li>Add support for text node without escaping (XSLT)</li>
911 <li>bug fixes for xmlCheckFilename</li>
912 <li>validation code bug fixes from Gary Pennington</li>
913 <li>Patch from Paul D. Smith correcting URI path normalization</li>
914 <li>Patch to allow simultaneous install of libxml-devel and
915 libxml2-devel</li>
916 <li>the example Makefile is now fixed</li>
917 <li>added HTML to the RPM packages</li>
918 <li>tree copying bugfixes</li>
919 <li>updates to Windows makefiles</li>
920 <li>optimisation patch from Bjorn Reese</li>
921</ul>
922
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]923<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]924<ul>
925 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
926 <li>added htmlHandleOmittedElem()</li>
927 <li>Applied Bjorn Reese's IPV6 first patch</li>
928 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]929 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]930</ul>
931
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]932<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]933<ul>
934 <li>Fix the Windows problems of 2.2.8</li>
935 <li>integrate OpenVMS patches</li>
936 <li>better handling of some nasty HTML input</li>
937 <li>Improved the XPointer implementation</li>
938 <li>integrate a number of provided patches</li>
939</ul>
940
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]941<h3>2.2.9: Nov 25 2000</h3>
942<ul>
943 <li>erroneous release :-(</li>
944</ul>
945
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]946<h3>2.2.8: Nov 13 2000</h3>
947<ul>
948 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
949 support</li>
950 <li>Patch in conditional section handling</li>
951 <li>updated MS compiler project</li>
952 <li>fixed some XPath problems</li>
953 <li>added an URI escaping function</li>
954 <li>some other bug fixes</li>
955</ul>
956
957<h3>2.2.7: Oct 31 2000</h3>
958<ul>
959 <li>added message redirection</li>
960 <li>XPath improvements (thanks TOM !)</li>
961 <li>xmlIOParseDTD() added</li>
962 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
963 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
964</ul>
965
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]966<h3>2.2.6: Oct 25 2000:</h3>
967<ul>
968 <li>Added an hash table module, migrated a number of internal structure to
969 those</li>
970 <li>Fixed a posteriori validation problems</li>
971 <li>HTTP module cleanups</li>
972 <li>HTML parser improvements (tag errors, script/style handling, attribute
973 normalization)</li>
974 <li>coalescing of adjacent text nodes</li>
975 <li>couple of XPath bug fixes, exported the internal API</li>
976</ul>
977
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]978<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]979<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]980 <li>XPointer implementation and testsuite</li>
981 <li>Lot of XPath fixes, added variable and functions registration, more
982 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]983 <li>Portability fixes, lots of enhancements toward an easy Windows build
984 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]985 <li>Late validation fixes</li>
986 <li>Integrated a lot of contributed patches</li>
987 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]988 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]989</ul>
990
991<h3>2.2.4: Oct 1 2000:</h3>
992<ul>
993 <li>main XPath problem fixed</li>
994 <li>Integrated portability patches for Windows</li>
995 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]996</ul>
997
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]998<h3>2.2.3: Sep 17 2000</h3>
999<ul>
1000 <li>bug fixes</li>
1001 <li>cleanup of entity handling code</li>
1002 <li>overall review of all loops in the parsers, all sprintf usage has been
1003 checked too</li>
1004 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
1005 works smoothly now.</li>
1006</ul>
1007
1008<h3>1.8.10: Sep 6 2000</h3>
1009<ul>
1010 <li>bug fix release for some Gnome projects</li>
1011</ul>
1012
1013<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1014<ul>
1015 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]1016 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1017</ul>
1018
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1019<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1020<ul>
1021 <li>a purely bug fixes release</li>
1022 <li>fixed an encoding support problem when parsing from a memory block</li>
1023 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1024 <li>removed a bug in the function allowing to override the memory
1025 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1026</ul>
1027
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1028<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]1029<ul>
1030 <li>applied a lot of portability fixes</li>
1031 <li>better encoding support/cleanup and saving (content is now always
1032 encoded in UTF-8)</li>
1033 <li>the HTML parser now correctly handles encodings</li>
1034 <li>added xmlHasProp()</li>
1035 <li>fixed a serious problem with &amp;#38;</li>
1036 <li>propagated the fix to FTP client</li>
1037 <li>cleanup, bugfixes, etc ...</li>
1038 <li>Added a page about <a href="encoding.html">libxml Internationalization
1039 support</a></li>
1040</ul>
1041
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1042<h3>1.8.9: July 9 2000</h3>
1043<ul>
1044 <li>fixed the spec the RPMs should be better</li>
1045 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
1046 rpmfind users problem</li>
1047</ul>
1048
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]1049<h3>2.1.1: July 1 2000</h3>
1050<ul>
1051 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1052 <li>improvements on the HTML parser</li>
1053</ul>
1054
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1055<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1056<ul>
1057 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1058 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1059 about &amp;#38; charref parsing</li>
1060 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1061 also contains numerous fixes and enhancements:
1062 <ul>
1063 <li>added xmlStopParser() to stop parsing</li>
1064 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1065 <li>includes XPath patches provided by Picdar Technology</li>
1066 <li>tried to fix as much as possible DtD validation and namespace
1067 related problems</li>
1068 <li>output to a given encoding has been added/tested</li>
1069 <li>lot of various fixes</li>
1070 </ul>
1071 </li>
1072</ul>
1073
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1074<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1075<ul>
1076 <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]1077 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1078 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1079 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1080 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1081 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1082 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1083 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1084 <pre>#include "xxx.h"</pre>
1085 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1086 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1087 <li>the memory allocation routines used by libxml can now be overloaded
1088 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1089 <li>The previously CVS only tool tester has been renamed
1090 <strong>xmllint</strong> and is now installed as part of the libxml2
1091 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1092 <li>The I/O interface has been revamped. There is now ways to plug in
1093 specific I/O modules, either at the URI scheme detection level using
1094 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1095 parser context using xmlCreateIOParserCtxt()</li>
1096 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1097 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1098 <li>a number of optional features of libxml can now be excluded at
1099 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1100</ul>
1101
1102<h3>2.0.0beta: Mar 14 2000</h3>
1103<ul>
1104 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1105 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1106 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1107 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1108 <li>This version is now the head in the Gnome CVS base, the old one is
1109 available under the tag LIB_XML_1_X</li>
1110 <li>This includes a very large set of changes. Froma programmatic point of
1111 view applications should not have to be modified too much, check the <a
1112 href="upgrade.html">upgrade page</a></li>
1113 <li>Some interfaces may changes (especially a bit about encoding).</li>
1114 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1115 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1116 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1117 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1118 <li>Better handling of entities, especially well formedness checking
1119 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1120 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1121 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1122 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1123 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1124 </ul>
1125 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1126 <li>Serious progress were made toward compliance, <a
1127 href="conf/result.html">here are the result of the test</a> against the
1128 OASIS testsuite (except the japanese tests since I don't support that
1129 encoding yet). This URL is rebuilt every couple of hours using the CVS
1130 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1131</ul>
1132
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1133<h3>1.8.7: Mar 6 2000</h3>
1134<ul>
1135 <li>This is a bug fix release:</li>
1136 <li>It is possible to disable the ignorable blanks heuristic used by
1137 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1138 that for adherence to XML spec, this behaviour will be disabled by
1139 default in 2.x . The same function will allow to keep compatibility for
1140 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1141 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1142 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1143 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1144 compilation on some platforms has been fixed</li>
1145 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1146 URIs</li>
1147</ul>
1148
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1149<h3>1.8.6: Jan 31 2000</h3>
1150<ul>
1151 <li>added a nanoFTP transport module, debugged until the new version of <a
1152 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1153 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1154</ul>
1155
1156<h3>1.8.5: Jan 21 2000</h3>
1157<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1158 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1159 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1160 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1161 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1162 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1163 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1164 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1165 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1166</ul>
1167
1168<h3>1.8.4: Jan 13 2000</h3>
1169<ul>
1170 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1171 <li>all exit() call should have been removed from libxml</li>
1172 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1173 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1174</ul>
1175
1176<h3>1.8.3: Jan 5 2000</h3>
1177<ul>
1178 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1179 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1180 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1181 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1182 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1183 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1184 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1185 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1186 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1187</ul>
1188
1189<h3>1.8.2: Dec 21 1999</h3>
1190<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1191 <li>I got another problem with includes and C++, I hope this issue is fixed
1192 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1193 <li>Added a few tree modification functions: xmlReplaceNode,
1194 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1195 xmlDocSetRootElement</li>
1196 <li>Tried to improve the HTML output with help from <a
1197 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1198</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1199
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1200<h3>1.8.1: Dec 18 1999</h3>
1201<ul>
1202 <li>various patches to avoid troubles when using libxml with C++ compilers
1203 the "namespace" keyword and C escaping in include files</li>
1204 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1205 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1206 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1207 <li>fixed a posteriori validation (validation after parsing, or by using a
1208 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1209 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1210</ul>
1211
1212<h3>1.8.0: Dec 12 1999</h3>
1213<ul>
1214 <li>cleanup, especially memory wise</li>
1215 <li>the parser should be more reliable, especially the HTML one, it should
1216 not crash, whatever the input !</li>
1217 <li>Integrated various patches, especially a speedup improvement for large
1218 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1219 configure with --with-buffers to enable them.</li>
1220 <li>attribute normalization, oops should have been added long ago !</li>
1221 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1222 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1223</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1224
1225<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1226<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1227 <li>Lots of HTML improvement</li>
1228 <li>Fixed some errors when saving both XML and HTML</li>
1229 <li>More examples, the regression tests should now look clean</li>
1230 <li>Fixed a bug with contiguous charref</li>
1231</ul>
1232
1233<h3>1.7.3: Sep 29 1999</h3>
1234<ul>
1235 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1236 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1237 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1238</ul>
1239
1240<h3>1.7.1: Sep 24 1999</h3>
1241<ul>
1242 <li>The basic type for strings manipulated by libxml has been renamed in
1243 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1244 is that CHAR was conflicting with a predefined type on Windows. However
1245 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1246 <strong>#define </strong>.</li>
1247 <li>Changed another error : the use of a structure field called errno, and
1248 leading to troubles on platforms where it's a macro</li>
1249</ul>
1250
1251<h3>1.7.0: sep 23 1999</h3>
1252<ul>
1253 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1254 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1255 <li>Added an errno to report errors by another mean than a simple printf
1256 like callback</li>
1257 <li>Finished ID/IDREF support and checking when validation</li>
1258 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1259 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1260 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1261 implementation</li>
1262 <li>Added an HTML parser front-end</li>
1263</ul>
1264
1265<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1266
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1267<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]1268markup-based structured documents. Here is <a name="example">an example XML
1269document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1270<pre>&lt;?xml version="1.0"?&gt;
1271&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1272 &lt;head&gt;
1273 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1274 &lt;/head&gt;
1275 &lt;chapter&gt;
1276 &lt;title&gt;The Linux adventure&lt;/title&gt;
1277 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1278 &lt;image href="linus.gif"/&gt;
1279 &lt;p&gt;...&lt;/p&gt;
1280 &lt;/chapter&gt;
1281&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1282
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1283<p>The first line specifies that it's an XML document and gives useful
1284information about its encoding. Then the document is a text format whose
1285structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1286to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1287(no content), a single tag can serve as both the opening and closing tag if
1288it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1289that, for example, the image tag has no content (just an attribute) and is
1290closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1291
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1292<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]1293structured document maintenance (where it follows the steps of SGML) to
1294simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1295spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1296it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1297
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1298<h2><a name="XSLT">XSLT</a></h2>
1299
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1300<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1301
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1302<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1303language for transforming XML documents into other XML documents (or
1304HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1305
1306<p>A separate library called libxslt is being built on top of libxml2. This
1307module "libxslt" can be found in the Gnome CVS base too.</p>
1308
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1309<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1310href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1311supported and the progresses on the <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1312href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog"
1313name="Changelog">Changelog</a></p>
1314
1315<h2><a name="Python">Python and bindings</a></h2>
1316
1317<p>There is a number of language bindings and wrappers available for libxml2,
1318the list below is not exhaustive. Please contact the <a
1319href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
1320(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
1321order to get updates to this list or to discuss the specific topic of libxml2
1322or libxslt wrappers or bindings:</p>
1323<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1324 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
1325 for libxml:<br>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1326 Website: <a
1327 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
1328 Download: <a
1329 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
1330 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
1331 based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
1332 <li><a
1333 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1334 Sergeant</a> developped <a
1335 href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
1336 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
1337 application server</a></li>
1338 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
1339 earlier version of the libxml/libxslt <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1340 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
1341 <li>Petr Kozelka provides <a
1342 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
1343 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
1344 <li>Wai-Sun "Squidster" Chia provides <a
1345 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
1346 libxml2 bindings are also available in Ruby through the <a
1347 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
1348 maintained by Tobias Peters.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1349 <li>Steve Ball and contributors maintains <a
1350 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
1351 Tcl</a></li>
1352 <li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1353</ul>
1354
1355<p>The distribution includes a set of Python bindings, which are garanteed to
1356be maintained as part of the library in the future, though the Python
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]1357interface have not yet reached the maturity of the C API.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1358
1359<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]1360<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1361 <li>If you use an RPM based distribution, simply install the <a
1362 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python
1363 RPM</a> (and if needed the <a
1364 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
1365 RPM</a>).</li>
1366 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
1367 module distribution</a> corresponding to your installed version of
1368 libxml2 and libxslt. Note that to install it you will need both libxml2
1369 and libxslt installed and run "python setup.py build install" in the
1370 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]1371</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1372
1373<p>The distribution includes a set of examples and regression tests for the
1374python bindings in the <code>python/tests</code> directory. Here are some
1375excepts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1376
1377<h3>tst.py:</h3>
1378
1379<p>This is a basic test of the file interface and DOM navigation:</p>
1380<pre>import libxml2
1381
1382doc = libxml2.parseFile("tst.xml")
1383if doc.name != "tst.xml":
1384 print "doc.name failed"
1385 sys.exit(1)
1386root = doc.children
1387if root.name != "doc":
1388 print "root.name failed"
1389 sys.exit(1)
1390child = root.children
1391if child.name != "foo":
1392 print "child.name failed"
1393 sys.exit(1)
1394doc.freeDoc()</pre>
1395
1396<p>The Python module is called libxml2, parseFile is the equivalent of
1397xmlParseFile (most of the bindings are automatically generated, and the xml
1398prefix is removed and the casing convention are kept). All node seen at the
1399binding level share the same subset of accesors:</p>
1400<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1401 <li><code>name</code> : returns the node name</li>
1402 <li><code>type</code> : returns a string indicating the node
1403 typ<code>e</code></li>
1404 <li><code>content</code> : returns the content of the node, it is based on
1405 xmlNodeGetContent() and hence is recursive.</li>
1406 <li><code>parent</code> , <code>children</code>, <code>last</code>,
1407 <code>next</code>, <code>prev</code>, <code>doc</code>,
1408 <code>properties</code>: pointing to the associated element in the tree,
1409 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1410</ul>
1411
1412<p>Also note the need to explicitely deallocate documents with freeDoc() .
1413Reference counting for libxml2 trees would need quite a lot of work to
1414function properly, and rather than risk memory leaks if not implemented
1415correctly it sounds safer to have an explicit function to free a tree. The
1416wrapper python objects like doc, root or child are them automatically garbage
1417collected.</p>
1418
1419<h3>validate.py:</h3>
1420
1421<p>This test check the validation interfaces and redirection of error
1422messages:</p>
1423<pre>import libxml2
1424
1425#desactivate error messages from the validation
1426def noerr(ctx, str):
1427 pass
1428
1429libxml2.registerErrorHandler(noerr, None)
1430
1431ctxt = libxml2.createFileParserCtxt("invalid.xml")
1432ctxt.validate(1)
1433ctxt.parseDocument()
1434doc = ctxt.doc()
1435valid = ctxt.isValid()
1436doc.freeDoc()
1437if valid != 0:
1438 print "validity chec failed"</pre>
1439
1440<p>The first thing to notice is the call to registerErrorHandler(), it
1441defines a new error handler global to the library. It is used to avoid seeing
1442the error messages when trying to validate the invalid document.</p>
1443
1444<p>The main interest of that test is the creation of a parser context with
1445createFileParserCtxt() and how the behaviour can be changed before calling
1446parseDocument() . Similary the informations resulting from the parsing phase
1447are also available using context methods.</p>
1448
1449<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
1450C function interfaces in terms of objects method as much as possible. The
1451best to get a complete view of what methods are supported is to look at the
1452libxml2.py module containing all the wrappers.</p>
1453
1454<h3>push.py:</h3>
1455
1456<p>This test show how to activate the push parser interface:</p>
1457<pre>import libxml2
1458
1459ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
1460ctxt.parseChunk("/&gt;", 2, 1)
1461doc = ctxt.doc()
1462
1463doc.freeDoc()</pre>
1464
1465<p>The context is created with a speciall call based on the
1466xmlCreatePushParser() from the C library. The first argument is an optional
1467SAX callback object, then the initial set of data, the lenght and the name of
1468the resource in case URI-References need to be computed by the parser.</p>
1469
1470<p>Then the data are pushed using the parseChunk() method, the last call
1471setting the thrird argument terminate to 1.</p>
1472
1473<h3>pushSAX.py:</h3>
1474
1475<p>this test show the use of the event based parsing interfaces. In this case
1476the parser does not build a document, but provides callback information as
1477the parser makes progresses analyzing the data being provided:</p>
1478<pre>import libxml2
1479log = ""
1480
1481class callback:
1482 def startDocument(self):
1483 global log
1484 log = log + "startDocument:"
1485
1486 def endDocument(self):
1487 global log
1488 log = log + "endDocument:"
1489
1490 def startElement(self, tag, attrs):
1491 global log
1492 log = log + "startElement %s %s:" % (tag, attrs)
1493
1494 def endElement(self, tag):
1495 global log
1496 log = log + "endElement %s:" % (tag)
1497
1498 def characters(self, data):
1499 global log
1500 log = log + "characters: %s:" % (data)
1501
1502 def warning(self, msg):
1503 global log
1504 log = log + "warning: %s:" % (msg)
1505
1506 def error(self, msg):
1507 global log
1508 log = log + "error: %s:" % (msg)
1509
1510 def fatalError(self, msg):
1511 global log
1512 log = log + "fatalError: %s:" % (msg)
1513
1514handler = callback()
1515
1516ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
1517chunk = " url='tst'&gt;b"
1518ctxt.parseChunk(chunk, len(chunk), 0)
1519chunk = "ar&lt;/foo&gt;"
1520ctxt.parseChunk(chunk, len(chunk), 1)
1521
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame]1522reference = "startDocument:startElement foo {'url': 'tst'}:" + \
1523 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1524if log != reference:
1525 print "Error got: %s" % log
1526 print "Exprected: %s" % reference</pre>
1527
1528<p>The key object in that test is the handler, it provides a number of entry
1529points which can be called by the parser as it makes progresses to indicate
1530the information set obtained. The full set of callback is larger than what
1531the callback class in that specific example implements (see the SAX
1532definition for a complete list). The wrapper will only call those supplied by
1533the object when activated. The startElement receives the names of the element
1534and a dictionnary containing the attributes carried by this element.</p>
1535
1536<p>Also note that the reference string generated from the callback shows a
1537single character call even though the string "bar" is passed to the parser
1538from 2 different call to parseChunk()</p>
1539
1540<h3>xpath.py:</h3>
1541
1542<p>This is a basic test of XPath warppers support</p>
1543<pre>import libxml2
1544
1545doc = libxml2.parseFile("tst.xml")
1546ctxt = doc.xpathNewContext()
1547res = ctxt.xpathEval("//*")
1548if len(res) != 2:
1549 print "xpath query: wrong node set size"
1550 sys.exit(1)
1551if res[0].name != "doc" or res[1].name != "foo":
1552 print "xpath query: wrong node set value"
1553 sys.exit(1)
1554doc.freeDoc()
1555ctxt.xpathFreeContext()</pre>
1556
1557<p>This test parses a file, then create an XPath context to evaluate XPath
1558expression on it. The xpathEval() method execute an XPath query and returns
1559the result mapped in a Python way. String and numbers are natively converted,
1560and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
1561the document, the XPath context need to be freed explicitely, also not that
1562the result of the XPath query may point back to the document tree and hence
1563the document must be freed after the result of the query is used.</p>
1564
1565<h3>xpathext.py:</h3>
1566
1567<p>This test shows how to extend the XPath engine with functions written in
1568python:</p>
1569<pre>import libxml2
1570
1571def foo(ctx, x):
1572 return x + 1
1573
1574doc = libxml2.parseFile("tst.xml")
1575ctxt = doc.xpathNewContext()
1576libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
1577res = ctxt.xpathEval("foo(1)")
1578if res != 2:
1579 print "xpath extension failure"
1580doc.freeDoc()
1581ctxt.xpathFreeContext()</pre>
1582
1583<p>Note how the extension function is registered with the context (but that
1584part is not yet finalized, ths may change slightly in the future).</p>
1585
1586<h3>tstxpath.py:</h3>
1587
1588<p>This test is similar to the previousone but shows how the extension
1589function can access the XPath evaluation context:</p>
1590<pre>def foo(ctx, x):
1591 global called
1592
1593 #
1594 # test that access to the XPath evaluation contexts
1595 #
1596 pctxt = libxml2.xpathParserContext(_obj=ctx)
1597 ctxt = pctxt.context()
1598 called = ctxt.function()
1599 return x + 1</pre>
1600
1601<p>All the interfaces around the XPath parser(or rather evaluation) context
1602are not finalized, but it should be sufficient to do contextual work at the
1603evaluation point.</p>
1604
1605<h3>Memory debugging:</h3>
1606
1607<p>last but not least, all tests starts with the following prologue:</p>
1608<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1609libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1610
1611<p>and ends with the following epilogue:</p>
1612<pre>#memory debug specific
1613libxml2.cleanupParser()
1614if libxml2.debugMemory(1) == 0:
1615 print "OK"
1616else:
1617 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
1618 libxml2.dumpMemory()</pre>
1619
1620<p>Those activate the memory debugging interface of libxml2 where all
1621alloacted block in the library are tracked. The prologue then cleans up the
1622library state and checks that all allocated memory has been freed. If not it
1623calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1624
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1625<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1626
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1627<p>Libxml is made of multiple components; some of them are optional, and most
1628of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1629<ul>
1630 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1631 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1632 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1633 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1634 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1635 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1636 <li>a SAX tree module to build an in-memory DOM representation</li>
1637 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1638 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1639 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1640 (optional)</li>
1641 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1642</ul>
1643
1644<p>Graphically this gives the following:</p>
1645
1646<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1647
1648<p></p>
1649
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1650<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1651
1652<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1653returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1654<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1655as the file name, the document type, and a <strong>children</strong> pointer
1656which is the root of the document (or more exactly the first child under the
1657root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1658chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1659relationship. An xmlNode can also carry properties (a chain of xmlAttr
1660structures). An attribute may have a value which is a list of TEXT or
1661ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1662
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1663<p>Here is an example (erroneous with respect to the XML spec since there
1664should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1665
1666<p><img src="structure.gif" alt=" structure.gif "></p>
1667
1668<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1669called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1670prints them back as parsed. This is useful for detecting errors both in XML
1671code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1672which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1673result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1674<pre>DOCUMENT
1675version=1.0
1676standalone=true
1677 ELEMENT EXAMPLE
1678 ATTRIBUTE prop1
1679 TEXT
1680 content=gnome is great
1681 ATTRIBUTE prop2
1682 ENTITY_REF
1683 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1684 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1685 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1686 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1687 TEXT
1688 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1689 ELEMENT chapter
1690 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1691 TEXT
1692 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1693 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1694 TEXT
1695 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1696 ELEMENT image
1697 ATTRIBUTE href
1698 TEXT
1699 content=linus.gif
1700 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1701 TEXT
1702 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1703
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1704<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1705
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1706<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1707
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1708<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1709memory. 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]1710loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1711a <strong>callback-based interface</strong> to the parser. Before parsing,
1712the application layer registers a customized set of callbacks which are
1713called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1714
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1715<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]1716libxml, see the <a
1717href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1718documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1719Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1720
1721<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1722program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1723binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1724distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1725testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1726<pre>SAX.setDocumentLocator()
1727SAX.startDocument()
1728SAX.getEntity(amp)
1729SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1730SAX.characters( , 3)
1731SAX.startElement(head)
1732SAX.characters( , 4)
1733SAX.startElement(title)
1734SAX.characters(Welcome to Gnome, 16)
1735SAX.endElement(title)
1736SAX.characters( , 3)
1737SAX.endElement(head)
1738SAX.characters( , 3)
1739SAX.startElement(chapter)
1740SAX.characters( , 4)
1741SAX.startElement(title)
1742SAX.characters(The Linux adventure, 19)
1743SAX.endElement(title)
1744SAX.characters( , 4)
1745SAX.startElement(p)
1746SAX.characters(bla bla bla ..., 15)
1747SAX.endElement(p)
1748SAX.characters( , 4)
1749SAX.startElement(image, href='linus.gif')
1750SAX.endElement(image)
1751SAX.characters( , 4)
1752SAX.startElement(p)
1753SAX.characters(..., 3)
1754SAX.endElement(p)
1755SAX.characters( , 3)
1756SAX.endElement(chapter)
1757SAX.characters( , 1)
1758SAX.endElement(EXAMPLE)
1759SAX.endDocument()</pre>
1760
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1761<p>Most of the other interfaces of libxml are based on the DOM tree-building
1762facility, so nearly everything up to the end of this document presupposes the
1763use of the standard DOM tree build. Note that the DOM tree itself is built by
1764a set of registered default callbacks, without internal specific
1765interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1766
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1767<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1768
1769<p>Table of Content:</p>
1770<ol>
1771 <li><a href="#General5">General overview</a></li>
1772 <li><a href="#definition">The definition</a></li>
1773 <li><a href="#Simple">Simple rules</a>
1774 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1775 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1776 <li><a href="#Declaring">Declaring elements</a></li>
1777 <li><a href="#Declaring1">Declaring attributes</a></li>
1778 </ol>
1779 </li>
1780 <li><a href="#Some">Some examples</a></li>
1781 <li><a href="#validate">How to validate</a></li>
1782 <li><a href="#Other">Other resources</a></li>
1783</ol>
1784
1785<h3><a name="General5">General overview</a></h3>
1786
1787<p>Well what is validation and what is a DTD ?</p>
1788
1789<p>DTD is the acronym for Document Type Definition. This is a description of
1790the content for a familly of XML files. This is part of the XML 1.0
1791specification, and alows to describe and check that a given document instance
1792conforms to a set of rules detailing its structure and content.</p>
1793
1794<p>Validation is the process of checking a document against a DTD (more
1795generally against a set of construction rules).</p>
1796
1797<p>The validation process and building DTDs are the two most difficult parts
1798of the XML life cycle. Briefly a DTD defines all the possibles element to be
1799found within your document, what is the formal shape of your document tree
1800(by defining the allowed content of an element, either text, a regular
1801expression for the allowed list of children, or mixed content i.e. both text
1802and children). The DTD also defines the allowed attributes for all elements
1803and the types of the attributes.</p>
1804
1805<h3><a name="definition1">The definition</a></h3>
1806
1807<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1808href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1809Rev1</a>):</p>
1810<ul>
1811 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1812 elements</a></li>
1813 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1814 attributes</a></li>
1815</ul>
1816
1817<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1818ancient...</p>
1819
1820<h3><a name="Simple1">Simple rules</a></h3>
1821
1822<p>Writing DTD can be done in multiple ways, the rules to build them if you
1823need something fixed or something which can evolve over time can be radically
1824different. Really complex DTD like Docbook ones are flexible but quite harder
1825to design. I will just focuse on DTDs for a formats with a fixed simple
1826structure. It is just a set of basic rules, and definitely not exhaustive nor
1827useable for complex DTD design.</p>
1828
1829<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1830
1831<p>Assuming the top element of the document is <code>spec</code> and the dtd
1832is placed in the file <code>mydtd</code> in the subdirectory
1833<code>dtds</code> of the directory from where the document were loaded:</p>
1834
1835<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1836
1837<p>Notes:</p>
1838<ul>
1839 <li>the system string is actually an URI-Reference (as defined in <a
1840 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1841 full URL string indicating the location of your DTD on the Web, this is a
1842 really good thing to do if you want others to validate your document</li>
1843 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1844 magic string) so that the DTd is looked up in catalogs on the client side
1845 without having to locate it on the web</li>
1846 <li>a dtd contains a set of elements and attributes declarations, but they
1847 don't define what the root of the document should be. This is explicitely
1848 told to the parser/validator as the first element of the
1849 <code>DOCTYPE</code> declaration.</li>
1850</ul>
1851
1852<h4><a name="Declaring2">Declaring elements</a>:</h4>
1853
1854<p>The following declares an element <code>spec</code>:</p>
1855
1856<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1857
1858<p>it also expresses that the spec element contains one <code>front</code>,
1859one <code>body</code> and one optionnal <code>back</code> children elements
1860in this order. The declaration of one element of the structure and its
1861content are done in a single declaration. Similary the following declares
1862<code>div1</code> elements:</p>
1863
Daniel Veillard51737272002-01-23 23:10:38 +0000[diff] [blame]1864<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2?)&gt;</code></p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1865
1866<p>means div1 contains one <code>head</code> then a series of optional
1867<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1868optional <code>div2</code>. And last but not least an element can contain
1869text:</p>
1870
1871<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1872
1873<p><code>b</code> contains text or being of mixed content (text and elements
1874in no particular order):</p>
1875
1876<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1877
1878<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1879<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1880order.</p>
1881
1882<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1883
1884<p>again the attributes declaration includes their content definition:</p>
1885
1886<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1887
1888<p>means that the element <code>termdef</code> can have a <code>name</code>
1889attribute containing text (<code>CDATA</code>) and which is optionnal
1890(<code>#IMPLIED</code>). The attribute value can also be defined within a
1891set:</p>
1892
1893<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1894"ordered"&gt;</code></p>
1895
1896<p>means <code>list</code> element have a <code>type</code> attribute with 3
1897allowed values "bullets", "ordered" or "glossary" and which default to
1898"ordered" if the attribute is not explicitely specified.</p>
1899
1900<p>The content type of an attribute can be text (<code>CDATA</code>),
1901anchor/reference/references
1902(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1903(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1904(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1905<code>chapter</code> element can have an optional <code>id</code> attribute
1906of type <code>ID</code>, usable for reference from attribute of type
1907IDREF:</p>
1908
1909<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1910
1911<p>The last value of an attribute definition can be <code>#REQUIRED
1912</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1913meaning that it is optional, or the default value (possibly prefixed by
1914<code>#FIXED</code> if it is the only allowed).</p>
1915
1916<p>Notes:</p>
1917<ul>
1918 <li>usually the attributes pertaining to a given element are declared in a
1919 single expression, but it is just a convention adopted by a lot of DTD
1920 writers:
1921 <pre>&lt;!ATTLIST termdef
1922 id ID #REQUIRED
1923 name CDATA #IMPLIED&gt;</pre>
1924 <p>The previous construct defines both <code>id</code> and
1925 <code>name</code> attributes for the element <code>termdef</code></p>
1926 </li>
1927</ul>
1928
1929<h3><a name="Some1">Some examples</a></h3>
1930
1931<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1932contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1933example shows an XML file where the simple DTD is directly included within
1934the document.</p>
1935
1936<h3><a name="validate1">How to validate</a></h3>
1937
1938<p>The simplest is to use the xmllint program comming with libxml. The
1939<code>--valid</code> option turn on validation of the files given as input,
1940for example the following validates a copy of the first revision of the XML
19411.0 specification:</p>
1942
1943<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1944
1945<p>the -- noout is used to not output the resulting tree.</p>
1946
1947<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1948a given DTD.</p>
1949
1950<p>Libxml exports an API to handle DTDs and validation, check the <a
1951href="http://xmlsoft.org/html/libxml-valid.html">associated
1952description</a>.</p>
1953
1954<h3><a name="Other1">Other resources</a></h3>
1955
1956<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1957will just list one for now, others pointers welcome:</p>
1958<ul>
1959 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1960</ul>
1961
1962<p>I suggest looking at the examples found under test/valid/dtd and any of
1963the large number of books available on XML. The dia example in test/valid
1964should be both simple and complete enough to allow you to build your own.</p>
1965
1966<p></p>
1967
1968<h2><a name="Memory">Memory Management</a></h2>
1969
1970<p>Table of Content:</p>
1971<ol>
1972 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1973 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1974 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1975 <li><a href="#Debugging">Debugging routines</a></li>
1976 <li><a href="#General4">General memory requirements</a></li>
1977</ol>
1978
1979<h3><a name="General3">General overview</a></h3>
1980
1981<p>The module <code><a
1982href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1983provides the interfaces to the libxml memory system:</p>
1984<ul>
1985 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1986 xmlMalloc() and xmlRealloc()</li>
1987 <li>those routines can be reallocated to a specific set of routine, by
1988 default the libc ones i.e. free(), malloc() and realloc()</li>
1989 <li>the xmlmemory.c module includes a set of debugging routine</li>
1990</ul>
1991
1992<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1993
1994<p>It is sometimes useful to not use the default memory allocator, either for
1995debugging, analysis or to implement a specific behaviour on memory management
1996(like on embedded systems). Two function calls are available to do so:</p>
1997<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]1998 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet
1999 ()</a> which return the current set of functions in use by the parser</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2000 <li><a
2001 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2002 which allow to set up a new set of memory allocation functions</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2003</ul>
2004
2005<p>Of course a call to xmlMemSetup() should probably be done before calling
2006any other libxml routines (unless you are sure your allocations routines are
2007compatibles).</p>
2008
2009<h3><a name="cleanup">Cleaning up after parsing</a></h3>
2010
2011<p>Libxml is not stateless, there is a few set of memory structures needing
2012allocation before the parser is fully functionnal (some encoding structures
2013for example). This also mean that once parsing is finished there is a tiny
2014amount of memory (a few hundred bytes) which can be recollected if you don't
2015reuse the parser immediately:</p>
2016<ul>
2017 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2018 ()</a> is a centralized routine to free the parsing states. Note that it
2019 won't deallocate any produced tree if any (use the xmlFreeDoc() and
2020 related routines for this).</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2021 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2022 ()</a> is the dual routine allowing to preallocate the parsing state
2023 which can be useful for example to avoid initialization reentrancy
2024 problems when using libxml in multithreaded applications</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2025</ul>
2026
2027<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
2028at the next invocation of parser routines, but be careful of the consequences
2029in multithreaded applications.</p>
2030
2031<h3><a name="Debugging">Debugging routines</a></h3>
2032
2033<p>When configured using --with-mem-debug flag (off by default), libxml uses
2034a set of memory allocation debugging routineskeeping track of all allocated
2035blocks and the location in the code where the routine was called. A couple of
2036other debugging routines allow to dump the memory allocated infos to a file
2037or call a specific routine when a given block number is allocated:</p>
2038<ul>
2039 <li><a
2040 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2041 <a
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2042 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
2043 and <a
2044 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
2045 are the memory debugging replacement allocation routines</li>
2046 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2047 ()</a> dumps all the informations about the allocated memory block lefts
2048 in the <code>.memdump</code> file</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2049</ul>
2050
2051<p>When developping libxml memory debug is enabled, the tests programs call
2052xmlMemoryDump () and the "make test" regression tests will check for any
2053memory leak during the full regression test sequence, this helps a lot
2054ensuring that libxml does not leak memory and bullet proof memory
2055allocations use (some libc implementations are known to be far too permissive
2056resulting in major portability problems!).</p>
2057
2058<p>If the .memdump reports a leak, it displays the allocation function and
2059also tries to give some informations about the content and structure of the
2060allocated blocks left. This is sufficient in most cases to find the culprit,
2061but not always. Assuming the allocation problem is reproductible, it is
2062possible to find more easilly:</p>
2063<ol>
2064 <li>write down the block number xxxx not allocated</li>
2065 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
2066 <li>run the program under a debugger and set a breakpoint on
2067 xmlMallocBreakpoint() a specific function called when this precise block
2068 is allocated</li>
2069 <li>when the breakpoint is reached you can then do a fine analysis of the
2070 allocation an step to see the condition resulting in the missing
2071 deallocation.</li>
2072</ol>
2073
2074<p>I used to use a commercial tool to debug libxml memory problems but after
2075noticing that it was not detecting memory leaks that simple mechanism was
2076used and proved extremely efficient until now.</p>
2077
2078<h3><a name="General4">General memory requirements</a></h3>
2079
2080<p>How much libxml memory require ? It's hard to tell in average it depends
2081of a number of things:</p>
2082<ul>
2083 <li>the parser itself should work in a fixed amout of memory, except for
2084 information maintained about the stacks of names and entities locations.
2085 The I/O and encoding handlers will probably account for a few KBytes.
2086 This is true for both the XML and HTML parser (though the HTML parser
2087 need more state).</li>
2088 <li>If you are generating the DOM tree then memory requirements will grow
2089 nearly lineary with the size of the data. In general for a balanced
2090 textual document the internal memory requirement is about 4 times the
2091 size of the UTF8 serialization of this document (exmple the XML-1.0
2092 recommendation is a bit more of 150KBytes and takes 650KBytes of main
2093 memory when parsed). Validation will add a amount of memory required for
2094 maintaining the external Dtd state which should be linear with the
2095 complexity of the content model defined by the Dtd</li>
2096 <li>If you don't care about the advanced features of libxml like
2097 validation, DOM, XPath or XPointer, but really need to work fixed memory
2098 requirements, then the SAX interface should be used.</li>
2099</ul>
2100
2101<p></p>
2102
2103<h2><a name="Encodings">Encodings support</a></h2>
2104
2105<p>Table of Content:</p>
2106<ol>
2107 <li><a href="encoding.html#What">What does internationalization support
2108 mean ?</a></li>
2109 <li><a href="encoding.html#internal">The internal encoding, how and
2110 why</a></li>
2111 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
2112 <li><a href="encoding.html#Default">Default supported encodings</a></li>
2113 <li><a href="encoding.html#extend">How to extend the existing
2114 support</a></li>
2115</ol>
2116
2117<h3><a name="What">What does internationalization support mean ?</a></h3>
2118
2119<p>XML was designed from the start to allow the support of any character set
2120by using Unicode. Any conformant XML parser has to support the UTF-8 and
2121UTF-16 default encodings which can both express the full unicode ranges. UTF8
2122is a variable length encoding whose greatest point are to resuse the same
2123emcoding for ASCII and to save space for Western encodings, but it is a bit
2124more complex to handle in practice. UTF-16 use 2 bytes per characters (and
2125sometimes combines two pairs), it makes implementation easier, but looks a
2126bit overkill for Western languages encoding. Moreover the XML specification
2127allows document to be encoded in other encodings at the condition that they
2128are clearly labelled as such. For example the following is a wellformed XML
2129document encoded in ISO-8859 1 and using accentuated letter that we French
2130likes for both markup and content:</p>
2131<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2132&lt;très&gt;là&lt;/très&gt;</pre>
2133
2134<p>Having internationalization support in libxml means the foolowing:</p>
2135<ul>
2136 <li>the document is properly parsed</li>
2137 <li>informations about it's encoding are saved</li>
2138 <li>it can be modified</li>
2139 <li>it can be saved in its original encoding</li>
2140 <li>it can also be saved in another encoding supported by libxml (for
2141 example straight UTF8 or even an ASCII form)</li>
2142</ul>
2143
2144<p>Another very important point is that the whole libxml API, with the
2145exception of a few routines to read with a specific encoding or save to a
2146specific encoding, is completely agnostic about the original encoding of the
2147document.</p>
2148
2149<p>It should be noted too that the HTML parser embedded in libxml now obbey
2150the same rules too, the following document will be (as of 2.2.2) handled in
2151an internationalized fashion by libxml too:</p>
2152<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
2153 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
2154&lt;html lang="fr"&gt;
2155&lt;head&gt;
2156 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
2157&lt;/head&gt;
2158&lt;body&gt;
2159&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
2160&lt;/html&gt;</pre>
2161
2162<h3><a name="internal">The internal encoding, how and why</a></h3>
2163
2164<p>One of the core decision was to force all documents to be converted to a
2165default internal encoding, and that encoding to be UTF-8, here are the
2166rationale for those choices:</p>
2167<ul>
2168 <li>keeping the native encoding in the internal form would force the libxml
2169 users (or the code associated) to be fully aware of the encoding of the
2170 original document, for examples when adding a text node to a document,
2171 the content would have to be provided in the document encoding, i.e. the
2172 client code would have to check it before hand, make sure it's conformant
2173 to the encoding, etc ... Very hard in practice, though in some specific
2174 cases this may make sense.</li>
2175 <li>the second decision was which encoding. From the XML spec only UTF8 and
2176 UTF16 really makes sense as being the two only encodings for which there
2177 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
2178 considered an intelligent choice too since it's a direct Unicode mapping
2179 support. I selected UTF-8 on the basis of efficiency and compatibility
2180 with surrounding software:
2181 <ul>
2182 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
2183 more costly to import and export CPU wise) is also far more compact
2184 than UTF-16 (and UCS-4) for a majority of the documents I see it used
2185 for right now (RPM RDF catalogs, advogato data, various configuration
2186 file formats, etc.) and the key point for today's computer
2187 architecture is efficient uses of caches. If one nearly double the
2188 memory requirement to store the same amount of data, this will trash
2189 caches (main memory/external caches/internal caches) and my take is
2190 that this harms the system far more than the CPU requirements needed
2191 for the conversion to UTF-8</li>
2192 <li>Most of libxml version 1 users were using it with straight ASCII
2193 most of the time, doing the conversion with an internal encoding
2194 requiring all their code to be rewritten was a serious show-stopper
2195 for using UTF-16 or UCS-4.</li>
2196 <li>UTF-8 is being used as the de-facto internal encoding standard for
2197 related code like the <a href="http://www.pango.org/">pango</a>
2198 upcoming Gnome text widget, and a lot of Unix code (yep another place
2199 where Unix programmer base takes a different approach from Microsoft
2200 - they are using UTF-16)</li>
2201 </ul>
2202 </li>
2203</ul>
2204
2205<p>What does this mean in practice for the libxml user:</p>
2206<ul>
2207 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
2208 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
2209 is simply to append 0 byte, as usual.</li>
2210 <li>One just need to make sure that when using chars outside the ASCII set,
2211 the values has been properly converted to UTF-8</li>
2212</ul>
2213
2214<h3><a name="implemente">How is it implemented ?</a></h3>
2215
2216<p>Let's describe how all this works within libxml, basically the I18N
2217(internationalization) support get triggered only during I/O operation, i.e.
2218when reading a document or saving one. Let's look first at the reading
2219sequence:</p>
2220<ol>
2221 <li>when a document is processed, we usually don't know the encoding, a
2222 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
2223 ASCII range (0-0x7F) maps with ASCII</li>
2224 <li>the xml declaration if available is parsed, including the encoding
2225 declaration. At that point, if the autodetected encoding is different
2226 from the one declared a call to xmlSwitchEncoding() is issued.</li>
2227 <li>If there is no encoding declaration, then the input has to be in either
2228 UTF-8 or UTF-16, if it is not then at some point when processing the
2229 input, the converter/checker of UTF-8 form will raise an encoding error.
2230 You may end-up with a garbled document, or no document at all ! Example:
2231 <pre>~/XML -&gt; ./xmllint err.xml
2232err.xml:1: error: Input is not proper UTF-8, indicate encoding !
2233&lt;très&gt;là&lt;/très&gt;
2234 ^
2235err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
2236&lt;très&gt;là&lt;/très&gt;
2237 ^</pre>
2238 </li>
2239 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
2240 then search the default registered encoding converters for that encoding.
2241 If it's not within the default set and iconv() support has been compiled
2242 it, it will ask iconv for such an encoder. If this fails then the parser
2243 will report an error and stops processing:
2244 <pre>~/XML -&gt; ./xmllint err2.xml
2245err2.xml:1: error: Unsupported encoding UnsupportedEnc
2246&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
2247 ^</pre>
2248 </li>
2249 <li>From that point the encoder process progressingly the input (it is
2250 plugged as a front-end to the I/O module) for that entity. It captures
2251 and convert on-the-fly the document to be parsed to UTF-8. The parser
2252 itself just does UTF-8 checking of this input and process it
2253 transparently. The only difference is that the encoding information has
2254 been added to the parsing context (more precisely to the input
2255 corresponding to this entity).</li>
2256 <li>The result (when using DOM) is an internal form completely in UTF-8
2257 with just an encoding information on the document node.</li>
2258</ol>
2259
2260<p>Ok then what's happen when saving the document (assuming you
2261colllected/built an xmlDoc DOM like structure) ? It depends on the function
2262called, xmlSaveFile() will just try to save in the original encoding, while
2263xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
2264encoding:</p>
2265<ol>
2266 <li>if no encoding is given, libxml will look for an encoding value
2267 associated to the document and if it exists will try to save to that
2268 encoding,
2269 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
2270 </li>
2271 <li>so if an encoding was specified, either at the API level or on the
2272 document, libxml will again canonalize the encoding name, lookup for a
2273 converter in the registered set or through iconv. If not found the
2274 function will return an error code</li>
2275 <li>the converter is placed before the I/O buffer layer, as another kind of
2276 buffer, then libxml will simply push the UTF-8 serialization to through
2277 that buffer, which will then progressively be converted and pushed onto
2278 the I/O layer.</li>
2279 <li>It is possible that the converter code fails on some input, for example
2280 trying to push an UTF-8 encoded chinese character through the UTF-8 to
2281 ISO-8859-1 converter won't work. Since the encoders are progressive they
2282 will just report the error and the number of bytes converted, at that
2283 point libxml will decode the offending character, remove it from the
2284 buffer and replace it with the associated charRef encoding &amp;#123; and
2285 resume the convertion. This guarante that any document will be saved
2286 without losses (except for markup names where this is not legal, this is
2287 a problem in the current version, in pactice avoid using non-ascci
2288 characters for tags or attributes names @@). A special "ascii" encoding
2289 name is used to save documents to a pure ascii form can be used when
2290 portability is really crucial</li>
2291</ol>
2292
2293<p>Here is a few examples based on the same test document:</p>
2294<pre>~/XML -&gt; ./xmllint isolat1
2295&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2296&lt;très&gt;là&lt;/très&gt;
2297~/XML -&gt; ./xmllint --encode UTF-8 isolat1
2298&lt;?xml version="1.0" encoding="UTF-8"?&gt;
2299&lt;très&gt;là  &lt;/très&gt;
2300~/XML -&gt; </pre>
2301
2302<p>The same processing is applied (and reuse most of the code) for HTML I18N
2303processing. Looking up and modifying the content encoding is a bit more
2304difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
2305so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
2306been provided. The parser also attempts to switch encoding on the fly when
2307detecting such a tag on input. Except for that the processing is the same
2308(and again reuses the same code).</p>
2309
2310<h3><a name="Default">Default supported encodings</a></h3>
2311
2312<p>libxml has a set of default converters for the following encodings
2313(located in encoding.c):</p>
2314<ol>
2315 <li>UTF-8 is supported by default (null handlers)</li>
2316 <li>UTF-16, both little and big endian</li>
2317 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
2318 <li>ASCII, useful mostly for saving</li>
2319 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
2320 predefined entities like &amp;copy; for the Copyright sign.</li>
2321</ol>
2322
2323<p>More over when compiled on an Unix platfor with iconv support the full set
2324of encodings supported by iconv can be instantly be used by libxml. On a
2325linux machine with glibc-2.1 the list of supported encodings and aliases fill
23263 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
2327various Japanese ones.</p>
2328
2329<h4>Encoding aliases</h4>
2330
2331<p>From 2.2.3, libxml has support to register encoding names aliases. The
2332goal is to be able to parse document whose encoding is supported but where
2333the name differs (for example from the default set of names accepted by
2334iconv). The following functions allow to register and handle new aliases for
2335existing encodings. Once registered libxml will automatically lookup the
2336aliases when handling a document:</p>
2337<ul>
2338 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
2339 <li>int xmlDelEncodingAlias(const char *alias);</li>
2340 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
2341 <li>void xmlCleanupEncodingAliases(void);</li>
2342</ul>
2343
2344<h3><a name="extend">How to extend the existing support</a></h3>
2345
2346<p>Well adding support for new encoding, or overriding one of the encoders
2347(assuming it is buggy) should not be hard, just write an input and output
2348conversion routines to/from UTF-8, and register them using
2349xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
2350called automatically if the parser(s) encounter such an encoding name
2351(register it uppercase, this will help). The description of the encoders,
2352their arguments and expected return values are described in the encoding.h
2353header.</p>
2354
2355<p>A quick note on the topic of subverting the parser to use a different
2356internal encoding than UTF-8, in some case people will absolutely want to
2357keep the internal encoding different, I think it's still possible (but the
2358encoding must be compliant with ASCII on the same subrange) though I didn't
2359tried it. The key is to override the default conversion routines (by
2360registering null encoders/decoders for your charsets), and bypass the UTF-8
2361checking of the parser by setting the parser context charset
2362(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2363there is no guarantee taht this will work. You may also have some troubles
2364saving back.</p>
2365
2366<p>Basically proper I18N support is important, this requires at least
2367libxml-2.0.0, but a lot of features and corrections are really available only
2368starting 2.2.</p>
2369
2370<h2><a name="IO">I/O Interfaces</a></h2>
2371
2372<p>Table of Content:</p>
2373<ol>
2374 <li><a href="#General1">General overview</a></li>
2375 <li><a href="#basic">The basic buffer type</a></li>
2376 <li><a href="#Input">Input I/O handlers</a></li>
2377 <li><a href="#Output">Output I/O handlers</a></li>
2378 <li><a href="#entities">The entities loader</a></li>
2379 <li><a href="#Example2">Example of customized I/O</a></li>
2380</ol>
2381
2382<h3><a name="General1">General overview</a></h3>
2383
2384<p>The module <code><a
2385href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2386the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2387<ul>
2388 <li>Entities loader, this is a routine which tries to fetch the entities
2389 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2390 don't look at the public identifier since libxml do not maintain a
2391 catalog. You can redefine you own entity loader by using
2392 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2393 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2394 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2395 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2396 input layer to handle fetching the informations to feed the parser. This
2397 provides buffering and is also a placeholder where the encoding
2398 convertors to UTF8 are piggy-backed.</li>
2399 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2400 task but when generating a serialization from a tree.</li>
2401 <li>A mechanism to register sets of I/O callbacks and associate them with
2402 specific naming schemes like the protocol part of the URIs.
2403 <p>This affect the default I/O operations and allows to use specific I/O
2404 handlers for certain names.</p>
2405 </li>
2406</ul>
2407
2408<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2409example in the HTML parser is the following:</p>
2410<ol>
2411 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2412 the parsing context and the URI string.</li>
2413 <li>the URI string is checked against the existing registered handlers
2414 using their match() callback function, if the HTTP module was compiled
2415 in, it is registered and its match() function will succeeds</li>
2416 <li>the open() function of the handler is called and if successful will
2417 return an I/O Input buffer</li>
2418 <li>the parser will the start reading from this buffer and progressively
2419 fetch information from the resource, calling the read() function of the
2420 handler until the resource is exhausted</li>
2421 <li>if an encoding change is detected it will be installed on the input
2422 buffer, providing buffering and efficient use of the conversion
2423 routines</li>
2424 <li>once the parser has finished, the close() function of the handler is
2425 called once and the Input buffer and associed resources are
2426 deallocated.</li>
2427</ol>
2428
2429<p>The user defined callbacks are checked first to allow overriding of the
2430default libxml I/O routines.</p>
2431
2432<h3><a name="basic">The basic buffer type</a></h3>
2433
2434<p>All the buffer manipulation handling is done using the
2435<code>xmlBuffer</code> type define in <code><a
2436href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2437resizable memory buffer. The buffer allocation strategy can be selected to be
2438either best-fit or use an exponential doubling one (CPU vs. memory use
2439tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2440<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2441system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2442of functions allows to manipulate buffers with names starting with the
2443<code>xmlBuffer...</code> prefix.</p>
2444
2445<h3><a name="Input">Input I/O handlers</a></h3>
2446
2447<p>An Input I/O handler is a simple structure
2448<code>xmlParserInputBuffer</code> containing a context associated to the
2449resource (file descriptor, or pointer to a protocol handler), the read() and
2450close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2451encoding handler are also present to support charset conversion when
2452needed.</p>
2453
2454<h3><a name="Output">Output I/O handlers</a></h3>
2455
2456<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2457Input one except the callbacks are write() and close().</p>
2458
2459<h3><a name="entities">The entities loader</a></h3>
2460
2461<p>The entity loader resolves requests for new entities and create inputs for
2462the parser. Creating an input from a filename or an URI string is done
2463through the xmlNewInputFromFile() routine. The default entity loader do not
2464handle the PUBLIC identifier associated with an entity (if any). So it just
2465calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2466XML).</p>
2467
2468<p>If you want to hook up a catalog mechanism then you simply need to
2469override the default entity loader, here is an example:</p>
2470<pre>#include &lt;libxml/xmlIO.h&gt;
2471
2472xmlExternalEntityLoader defaultLoader = NULL;
2473
2474xmlParserInputPtr
2475xmlMyExternalEntityLoader(const char *URL, const char *ID,
2476 xmlParserCtxtPtr ctxt) {
2477 xmlParserInputPtr ret;
2478 const char *fileID = NULL;
2479 /* lookup for the fileID depending on ID */
2480
2481 ret = xmlNewInputFromFile(ctxt, fileID);
2482 if (ret != NULL)
2483 return(ret);
2484 if (defaultLoader != NULL)
2485 ret = defaultLoader(URL, ID, ctxt);
2486 return(ret);
2487}
2488
2489int main(..) {
2490 ...
2491
2492 /*
2493 * Install our own entity loader
2494 */
2495 defaultLoader = xmlGetExternalEntityLoader();
2496 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2497
2498 ...
2499}</pre>
2500
2501<h3><a name="Example2">Example of customized I/O</a></h3>
2502
2503<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2504real use case</a>, xmlDocDump() closes the FILE * passed by the application
2505and this was a problem. The <a
2506href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2507new output handler with the closing call deactivated:</p>
2508<ol>
2509 <li>First define a new I/O ouput allocator where the output don't close the
2510 file:
2511 <pre>xmlOutputBufferPtr
2512xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2513    xmlOutputBufferPtr ret;
2514    
2515    if (xmlOutputCallbackInitialized == 0)
2516        xmlRegisterDefaultOutputCallbacks();
2517
2518    if (file == NULL) return(NULL);
2519    ret = xmlAllocOutputBuffer(encoder);
2520    if (ret != NULL) {
2521        ret-&gt;context = file;
2522        ret-&gt;writecallback = xmlFileWrite;
2523        ret-&gt;closecallback = NULL; /* No close callback */
2524    }
2525    return(ret); <br>
2526
2527
2528
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2529
2530
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2531
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2532
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2533
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]2534
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]2535
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]2536
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]2537
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]2538
Daniel Veillard9ae4b7a2001-12-13 14:24:09 +0000[diff] [blame]2539
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]2540
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]2541
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2542
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2543
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]2544
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]2545
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]2546
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]2547
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]2548
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]2549
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]2550
2551
2552
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2553
Daniel Veillard5c396542002-03-15 07:57:50 +0000[diff] [blame^]2554
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2555} </pre>
2556 </li>
2557 <li>And then use it to save the document:
2558 <pre>FILE *f;
2559xmlOutputBufferPtr output;
2560xmlDocPtr doc;
2561int res;
2562
2563f = ...
2564doc = ....
2565
2566output = xmlOutputBufferCreateOwn(f, NULL);
2567res = xmlSaveFileTo(output, doc, NULL);
2568 </pre>
2569 </li>
2570</ol>
2571
2572<h2><a name="Catalog">Catalog support</a></h2>
2573
2574<p>Table of Content:</p>
2575<ol>
2576 <li><a href="General2">General overview</a></li>
2577 <li><a href="#definition">The definition</a></li>
2578 <li><a href="#Simple">Using catalogs</a></li>
2579 <li><a href="#Some">Some examples</a></li>
2580 <li><a href="#reference">How to tune catalog usage</a></li>
2581 <li><a href="#validate">How to debug catalog processing</a></li>
2582 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2583 <li><a href="#implemento">The implementor corner quick review of the
2584 API</a></li>
2585 <li><a href="#Other">Other resources</a></li>
2586</ol>
2587
2588<h3><a name="General2">General overview</a></h3>
2589
2590<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2591(a file or a remote resource) references another entity. The catalog lookup
2592is inserted between the moment the reference is recognized by the software
2593(XML parser, stylesheet processing, or even images referenced for inclusion
2594in a rendering) and the time where loading that resource is actually
2595started.</p>
2596
2597<p>It is basically used for 3 things:</p>
2598<ul>
2599 <li>mapping from "logical" names, the public identifiers and a more
2600 concrete name usable for download (and URI). For example it can associate
2601 the logical name
2602 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2603 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2604 downloaded</p>
2605 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2606 </li>
2607 <li>remapping from a given URL to another one, like an HTTP indirection
2608 saying that
2609 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2610 <p>should really be looked at</p>
2611 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2612 </li>
2613 <li>providing a local cache mechanism allowing to load the entities
2614 associated to public identifiers or remote resources, this is a really
2615 important feature for any significant deployment of XML or SGML since it
2616 allows to avoid the aleas and delays associated to fetching remote
2617 resources.</li>
2618</ul>
2619
2620<h3><a name="definition">The definitions</a></h3>
2621
2622<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2623<ul>
2624 <li>the older SGML catalogs, the official spec is SGML Open Technical
2625 Resolution TR9401:1997, but is better understood by reading <a
2626 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2627 James Clark. This is relatively old and not the preferred mode of
2628 operation of libxml.</li>
2629 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]2630 Catalogs</a> is far more flexible, more recent, uses an XML syntax and
2631 should scale quite better. This is the default option of libxml.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2632</ul>
2633
2634<p></p>
2635
2636<h3><a name="Simple">Using catalog</a></h3>
2637
2638<p>In a normal environment libxml will by default check the presence of a
2639catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2640the processing is completely transparent to the document user. To take a
2641concrete example, suppose you are authoring a DocBook document, this one
2642starts with the following DOCTYPE definition:</p>
2643<pre>&lt;?xml version='1.0'?&gt;
2644&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2645 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2646
2647<p>When validating the document with libxml, the catalog will be
2648automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2649DocBk XML V3.1.4//EN" and the system identifier
2650"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2651been installed on your system and the catalogs actually point to them, libxml
2652will fetch them from the local disk.</p>
2653
2654<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2655DOCTYPE example it's a really old version, but is fine as an example.</p>
2656
2657<p>Libxml will check the catalog each time that it is requested to load an
2658entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2659your system is correctly configured all the authoring phase and processing
2660should use only local files, even if your document stays portable because it
2661uses the canonical public and system ID, referencing the remote document.</p>
2662
2663<h3><a name="Some">Some examples:</a></h3>
2664
2665<p>Here is a couple of fragments from XML Catalogs used in libxml early
2666regression tests in <code>test/catalogs</code> :</p>
2667<pre>&lt;?xml version="1.0"?&gt;
2668&lt;!DOCTYPE catalog PUBLIC
2669 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2670 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2671&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2672 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2673 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2674...</pre>
2675
2676<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2677written in XML, there is a specific namespace for catalog elements
2678"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2679catalog is a <code>public</code> mapping it allows to associate a Public
2680Identifier with an URI.</p>
2681<pre>...
2682 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2683 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2684...</pre>
2685
2686<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2687any URI starting with a given prefix should be looked at another URI
2688constructed by replacing the prefix with an new one. In effect this acts like
2689a cache system for a full area of the Web. In practice it is extremely useful
2690with a file prefix if you have installed a copy of those resources on your
2691local system.</p>
2692<pre>...
2693&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2694 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2695&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2696 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2697&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2698 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2699&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2700 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2701&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2702 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2703...</pre>
2704
2705<p>Delegation is the core features which allows to build a tree of catalogs,
2706easier to maintain than a single catalog, based on Public Identifier, System
2707Identifier or URI prefixes it instructs the catalog software to look up
2708entries in another resource. This feature allow to build hierarchies of
2709catalogs, the set of entries presented should be sufficient to redirect the
2710resolution of all DocBook references to the specific catalog in
2711<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2712references for DocBook 4.2.1 to a specific catalog installed at the same time
2713as the DocBook resources on the local machine.</p>
2714
2715<h3><a name="reference">How to tune catalog usage:</a></h3>
2716
2717<p>The user can change the default catalog behaviour by redirecting queries
2718to its own set of catalogs, this can be done by setting the
2719<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2720empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2721default catalog</p>
2722
2723<h3><a name="validate">How to debug catalog processing:</a></h3>
2724
2725<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2726make libxml output debugging informations for each catalog operations, for
2727example:</p>
2728<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2729warning: failed to load external entity "title.xml"
2730orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2731orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2732Failed to parse catalog /etc/xml/catalog
2733Failed to parse catalog /etc/xml/catalog
2734warning: failed to load external entity "title.xml"
2735Catalogs cleanup
2736orchis:~/XML -&gt; </pre>
2737
2738<p>The test/ent2 references an entity, running the parser from memory makes
2739the base URI unavailable and the the "title.xml" entity cannot be loaded.
2740Setting up the debug environment variable allows to detect that an attempt is
2741made to load the <code>/etc/xml/catalog</code> but since it's not present the
2742resolution fails.</p>
2743
2744<p>But the most advanced way to debug XML catalog processing is to use the
2745<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2746catalogs and make resolution queries to see what is going on. This is also
2747used for the regression tests:</p>
2748<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2749 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2750http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2751orchis:~/XML -&gt; </pre>
2752
2753<p>For debugging what is going on, adding one -v flags increase the verbosity
2754level to indicate the processing done (adding a second flag also indicate
2755what elements are recognized at parsing):</p>
2756<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2757 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2758Parsing catalog test/catalogs/docbook.xml's content
2759Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2760http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2761Catalogs cleanup
2762orchis:~/XML -&gt; </pre>
2763
2764<p>A shell interface is also available to debug and process multiple queries
2765(and for regression tests):</p>
2766<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2767 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2768&gt; help
2769Commands available:
2770public PublicID: make a PUBLIC identifier lookup
2771system SystemID: make a SYSTEM identifier lookup
2772resolve PublicID SystemID: do a full resolver lookup
2773add 'type' 'orig' 'replace' : add an entry
2774del 'values' : remove values
2775dump: print the current catalog state
2776debug: increase the verbosity level
2777quiet: decrease the verbosity level
2778exit: quit the shell
2779&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2780http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2781&gt; quit
2782orchis:~/XML -&gt; </pre>
2783
2784<p>This should be sufficient for most debugging purpose, this was actually
2785used heavily to debug the XML Catalog implementation itself.</p>
2786
2787<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2788
2789<p>Basically XML Catalogs are XML files, you can either use XML tools to
2790manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2791to create a catalog the -create option provide this facility:</p>
2792<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2793&lt;?xml version="1.0"?&gt;
2794&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2795 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2796&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2797orchis:~/XML -&gt; </pre>
2798
2799<p>By default xmlcatalog does not overwrite the original catalog and save the
2800result on the standard output, this can be overridden using the -noout
2801option. The <code>-add</code> command allows to add entries in the
2802catalog:</p>
2803<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2804 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2805 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2806orchis:~/XML -&gt; cat tst.xml
2807&lt;?xml version="1.0"?&gt;
2808&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2809 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2810&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2811&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2812 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2813&lt;/catalog&gt;
2814orchis:~/XML -&gt; </pre>
2815
2816<p>The <code>-add</code> option will always take 3 parameters even if some of
2817the XML Catalog constructs (like nextCatalog) will have only a single
2818argument, just pass a third empty string, it will be ignored.</p>
2819
2820<p>Similarly the <code>-del</code> option remove matching entries from the
2821catalog:</p>
2822<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2823 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2824&lt;?xml version="1.0"?&gt;
2825&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2826 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2827&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2828orchis:~/XML -&gt; </pre>
2829
2830<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2831exact and would have worked in a similar fashion with the Public ID
2832string.</p>
2833
2834<p>This is rudimentary but should be sufficient to manage a not too complex
2835catalog tree of resources.</p>
2836
2837<h3><a name="implemento">The implementor corner quick review of the
2838API:</a></h3>
2839
2840<p>First, and like for every other module of libxml, there is an
2841automatically generated <a href="html/libxml-catalog.html">API page for
2842catalog support</a>.</p>
2843
2844<p>The header for the catalog interfaces should be included as:</p>
2845<pre>#include &lt;libxml/catalog.h&gt;</pre>
2846
2847<p>The API is voluntarily kept very simple. First it is not obvious that
2848applications really need access to it since it is the default behaviour of
2849libxml (Note: it is possible to completely override libxml default catalog by
2850using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2851plug an application specific resolver).</p>
2852
2853<p>Basically libxml support 2 catalog lists:</p>
2854<ul>
2855 <li>the default one, global shared by all the application</li>
2856 <li>a per-document catalog, this one is built if the document uses the
2857 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2858 associated to the parser context and destroyed when the parsing context
2859 is destroyed.</li>
2860</ul>
2861
2862<p>the document one will be used first if it exists.</p>
2863
2864<h4>Initialization routines:</h4>
2865
2866<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2867used at startup to initialize the catalog, if the catalog should be
2868initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2869should be called before xmlInitializeCatalog() which would otherwise do a
2870default initialization first.</p>
2871
2872<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2873own catalog list if needed.</p>
2874
2875<h4>Preferences setup:</h4>
2876
2877<p>The XML Catalog spec requires the possibility to select default
2878preferences between public and system delegation,
2879xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2880xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2881be forbidden, allowed for global catalog, for document catalog or both, the
2882default is to allow both.</p>
2883
2884<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2885(through the xmlGenericError() mechanism).</p>
2886
2887<h4>Querying routines:</h4>
2888
2889<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2890and xmlCatalogResolveURI() are relatively explicit if you read the XML
2891Catalog specification they correspond to section 7 algorithms, they should
2892also work if you have loaded an SGML catalog with a simplified semantic.</p>
2893
2894<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2895operate on the document catalog list</p>
2896
2897<h4>Cleanup and Miscellaneous:</h4>
2898
2899<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2900the per-document equivalent.</p>
2901
2902<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2903first catalog in the global list, and xmlCatalogDump() allows to dump a
2904catalog state, those routines are primarily designed for xmlcatalog, I'm not
2905sure that exposing more complex interfaces (like navigation ones) would be
2906really useful.</p>
2907
2908<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2909it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2910provided because this functionality may be useful for client tools.</p>
2911
2912<h4>threaded environments:</h4>
2913
2914<p>Since the catalog tree is built progressively, some care has been taken to
2915try to avoid troubles in multithreaded environments. The code is now thread
2916safe assuming that the libxml library has been compiled with threads
2917support.</p>
2918
2919<p></p>
2920
2921<h3><a name="Other">Other resources</a></h3>
2922
2923<p>The XML Catalog specification is relatively recent so there isn't much
2924literature to point at:</p>
2925<ul>
2926 <li>You can find an good rant from Norm Walsh about <a
2927 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2928 need for catalogs</a>, it provides a lot of context informations even if
2929 I don't agree with everything presented.</li>
2930 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2931 catalog proposal</a> from John Cowan</li>
2932 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2933 Language</a> (RDDL) another catalog system but more oriented toward
2934 providing metadata for XML namespaces.</li>
2935 <li>the page from the OASIS Technical <a
2936 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2937 Resolution</a> who maintains XML Catalog, you will find pointers to the
2938 specification update, some background and pointers to others tools
2939 providing XML Catalog support</li>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2940 <li>Here is a <a href="buildDocBookCatalog">shell script</a> to generate
2941 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/
2942 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on
2943 the resources found on the system. Otherwise it will just create
2944 ~/xmlcatalog and ~/dbkxmlcatalog and doing:
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2945 <p><code>export XMLCATALOG=$HOME/xmlcatalog</code></p>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2946 <p>should allow to process DocBook documentations without requiring
2947 network accesses for the DTd or stylesheets</p>
2948 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2949 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2950 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems
2951 to work fine for me too</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2952 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2953 manual page</a></li>
2954</ul>
2955
2956<p>If you have suggestions for corrections or additions, simply contact
2957me:</p>
2958
2959<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2960
2961<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2962using the XML library from the C language. It is not intended to be
2963extensive. I hope the automatically generated documents will provide the
2964completeness required, but as a separate set of documents. The interfaces of
2965the XML library are by principle low level, there is nearly zero abstraction.
2966Those interested in a higher level API should <a href="#DOM">look at
2967DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2968
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2969<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2970separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2971interfaces</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]2972
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2973<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2974
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2975<p>Usually, the first thing to do is to read an XML input. The parser accepts
2976documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2977defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2978<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2979 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2980 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2981 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2982</dl>
2983<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2984 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2985 <dd><p>Parse an XML document contained in a (possibly compressed)
2986 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2987 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2988</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2989
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2990<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]2991failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2992
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2993<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2994
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2995<p>In order for the application to keep the control when the document is
2996being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2997interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2998<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2999 void *user_data,
3000 const char *chunk,
3001 int size,
3002 const char *filename);
3003int xmlParseChunk (xmlParserCtxtPtr ctxt,
3004 const char *chunk,
3005 int size,
3006 int terminate);</pre>
3007
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3008<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3009<pre> FILE *f;
3010
3011 f = fopen(filename, "r");
3012 if (f != NULL) {
3013 int res, size = 1024;
3014 char chars[1024];
3015 xmlParserCtxtPtr ctxt;
3016
3017 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3018 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3019 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
3020 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3021 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3022 xmlParseChunk(ctxt, chars, res, 0);
3023 }
3024 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3025 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3026 xmlFreeParserCtxt(ctxt);
3027 }
3028 }</pre>
3029
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3030<p>The HTML parser embedded into libxml also has a push interface; the
3031functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3032
3033<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
3034
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3035<p>The tree-building interface makes the parser memory-hungry, first loading
3036the document in memory and then building the tree itself. Reading a document
3037without building the tree is possible using the SAX interfaces (see SAX.h and
3038<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]3039Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3040limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3041<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3042
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3043<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3044
3045<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]3046there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3047also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
3048code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3049<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3050 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3051 xmlNodePtr tree, subtree;
3052
3053 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3054 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
3055 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
3056 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
3057 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3058 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3059 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3060 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
3061 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
3062 subtree = xmlNewChild(tree, NULL, "image", NULL);
3063 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3064
3065<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3066
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3067<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3068
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3069<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3070code has access to the internal structure of all the elements of the tree.
3071The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]3072<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3073<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3074example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3075<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3076
3077<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3078<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3079
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3080<p>points to the text node containing the chapter title "The Linux
3081adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3082
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3083<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]3084present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3085to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]3086<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3087
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3088<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3089
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3090<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3091is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3092<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3093 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
3094 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3095 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
3096 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3097 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3098</dl>
3099<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3100 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3101 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]3102 <dd><p>This function returns a pointer to new copy of the property
3103 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3104 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3105</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3106
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3107<p>Two functions are provided for reading and writing the text associated
3108with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3109<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3110 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3111 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3112 <dd><p>This function takes an "external" string and converts it to one
3113 text node or possibly to a list of entity and text nodes. All
3114 non-predefined entity references like &amp;Gnome; will be stored
3115 internally as entity nodes, hence the result of the function may not be
3116 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3117 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3118</dl>
3119<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3120 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3121 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3122 <dd><p>This function is the inverse of
3123 <code>xmlStringGetNodeList()</code>. It generates a new string
3124 containing the content of the text and entity nodes. Note the extra
3125 argument inLine. If this argument is set to 1, the function will expand
3126 entity references. For example, instead of returning the &amp;Gnome;
3127 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3128 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3129 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3130</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3131
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3132<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3133
3134<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3135<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3136 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3137 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3138 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3139 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3140</dl>
3141<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3142 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3143 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3144 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3145</dl>
3146<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3147 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3148 <dd><p>Saves the document to a file. In this case, the compression
3149 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3150 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3151</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3152
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3153<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3154
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3155<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3156accesses. The level of compression on saves can be turned on either globally
3157or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3158<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3159 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3160 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3161 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3162</dl>
3163<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3164 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3165 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3166 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3167</dl>
3168<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3169 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3170 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3171 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3172</dl>
3173<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3174 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3175 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3176 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3177</dl>
3178
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3179<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3180
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3181<p>Entities in principle are similar to simple C macros. An entity defines an
3182abbreviation for a given string that you can reuse many times throughout the
3183content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3184may occur frequently within a document, or to confine the change needed to a
3185document to a restricted area in the internal subset of the document (at the
3186beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3187<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31882 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31893 &lt;!ENTITY xml "Extensible Markup Language"&gt;
31904 ]&gt;
31915 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31926 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31937 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3194
3195<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]3196its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3197are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3198predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3199<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3200for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3201<strong>&amp;quot;</strong> for the character '"', and
3202<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3203
3204<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]3205substitute an entity's content so that you can see the replacement text in
3206your application. Or you may prefer to keep entity references as such in the
3207content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3208precious information (if the user went through the pain of explicitly
3209defining entities, he may have a a rather negative attitude if you blindly
3210susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3211href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3212function allows you to check and change the behaviour, which is to not
3213substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3214
3215<p>Here is the DOM tree built by libxml for the previous document in the
3216default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3217<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3218DOCUMENT
3219version=1.0
3220 ELEMENT EXAMPLE
3221 TEXT
3222 content=
3223 ENTITY_REF
3224 INTERNAL_GENERAL_ENTITY xml
3225 content=Extensible Markup Language
3226 TEXT
3227 content=</pre>
3228
3229<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3230<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3231DOCUMENT
3232version=1.0
3233 ELEMENT EXAMPLE
3234 TEXT
3235 content= Extensible Markup Language</pre>
3236
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3237<p>So, entities or no entities? Basically, it depends on your use case. I
3238suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3239entities in your XML document or data if you are not willing to handle the
3240entity references elements in the DOM tree.</p>
3241
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3242<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3243entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3244transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3245reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3246finding them in the input).</p>
3247
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3248<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3249on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3250non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3251then 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]3252strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]3253deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3254
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3255<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3256
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3257<p>The libxml library implements <a
3258href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
3259recognizing namespace contructs in the input, and does namespace lookup
3260automatically when building the DOM tree. A namespace declaration is
3261associated with an in-memory structure and all elements or attributes within
3262that namespace point to it. Hence testing the namespace is a simple and fast
3263equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3264
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3265<p>I suggest that people using libxml use a namespace, and declare it in the
3266root element of their document as the default namespace. Then they don't need
3267to 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]3268refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3269the size of the XML output significantly, but significantly increases its
3270value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3271<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
3272 &lt;elem1&gt;...&lt;/elem1&gt;
3273 &lt;elem2&gt;...&lt;/elem2&gt;
3274&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3275
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3276<p>The namespace value has to be an absolute URL, but the URL doesn't have to
3277point to any existing resource on the Web. It will bind all the element and
3278atributes with that URL. I suggest to use an URL within a domain you control,
3279and that the URL should contain some kind of version information if possible.
3280For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
3281namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3282
3283<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3284version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3285and if the version information don't match something you know, warn the user
3286and 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]3287namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3288same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3289associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3290just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3291<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3292prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3293
3294<p>@@Interfaces@@</p>
3295
3296<p>@@Examples@@</p>
3297
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3298<p>Usually people object to using namespaces together with validity checking.
3299I will try to make sure that using namespaces won't break validity checking,
3300so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3301suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3302<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3303flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3304from multiple DTDs will certainly break current validation schemes. I will
3305try to provide ways to do this, but this may not be portable or
3306standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3307
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3308<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3309
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3310<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3311
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3312<p>Version 2 of libxml is the first version introducing serious backward
3313incompatible changes. The main goals were:</p>
3314<ul>
3315 <li>a general cleanup. A number of mistakes inherited from the very early
3316 versions couldn't be changed due to compatibility constraints. Example
3317 the "childs" element in the nodes.</li>
3318 <li>Uniformization of the various nodes, at least for their header and link
3319 parts (doc, parent, children, prev, next), the goal is a simpler
3320 programming model and simplifying the task of the DOM implementors.</li>
3321 <li>better conformances to the XML specification, for example version 1.x
3322 had an heuristic to try to detect ignorable white spaces. As a result the
3323 SAX event generated were ignorableWhitespace() while the spec requires
3324 character() in that case. This also mean that a number of DOM node
3325 containing blank text may populate the DOM tree which were not present
3326 before.</li>
3327</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3328
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3329<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3330
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3331<p>So client code of libxml designed to run with version 1.x may have to be
3332changed to compile against version 2.x of libxml. Here is a list of changes
3333that I have collected, they may not be sufficient, so in case you find other
3334change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
3335mail</a>:</p>
3336<ol>
3337 <li>The package name have changed from libxml to libxml2, the library name
3338 is now -lxml2 . There is a new xml2-config script which should be used to
3339 select the right parameters libxml2</li>
3340 <li>Node <strong>childs</strong> field has been renamed
3341 <strong>children</strong> so s/childs/children/g should be applied
3342 (probablility of having "childs" anywere else is close to 0+</li>
3343 <li>The document don't have anymore a <strong>root</strong> element it has
3344 been replaced by <strong>children</strong> and usually you will get a
3345 list of element here. For example a Dtd element for the internal subset
3346 and it's declaration may be found in that list, as well as processing
3347 instructions or comments found before or after the document root element.
3348 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
3349 a document. Alternatively if you are sure to not reference Dtds nor have
3350 PIs or comments before or after the root element
3351 s/-&gt;root/-&gt;children/g will probably do it.</li>
3352 <li>The white space issue, this one is more complex, unless special case of
3353 validating parsing, the line breaks and spaces usually used for indenting
3354 and formatting the document content becomes significant. So they are
3355 reported by SAX and if your using the DOM tree, corresponding nodes are
3356 generated. Too approach can be taken:
3357 <ol>
3358 <li>lazy one, use the compatibility call
3359 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
3360 relying on a special (and possibly broken) set of heuristics of
3361 libxml to detect ignorable blanks. Don't complain if it breaks or
3362 make your application not 100% clean w.r.t. to it's input.</li>
3363 <li>the Right Way: change you code to accept possibly unsignificant
3364 blanks characters, or have your tree populated with weird blank text
3365 nodes. You can spot them using the comodity function
3366 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
3367 nodes.</li>
3368 </ol>
3369 <p>Note also that with the new default the output functions don't add any
3370 extra indentation when saving a tree in order to be able to round trip
3371 (read and save) without inflating the document with extra formatting
3372 chars.</p>
3373 </li>
3374 <li>The include path has changed to $prefix/libxml/ and the includes
3375 themselves uses this new prefix in includes instructions... If you are
3376 using (as expected) the
3377 <pre>xml2-config --cflags</pre>
3378 <p>output to generate you compile commands this will probably work out of
3379 the box</p>
3380 </li>
3381 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
3382 byte of the head of the document available for character detection.</li>
3383</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3384
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3385<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3386
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3387<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3388to allow smoth upgrade of existing libxml v1code while retaining
3389compatibility. They offers the following:</p>
3390<ol>
3391 <li>similar include naming, one should use
3392 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3393 <li>similar identifiers defined via macros for the child and root fields:
3394 respectively <strong>xmlChildrenNode</strong> and
3395 <strong>xmlRootNode</strong></li>
3396 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3397 inserted once in the client code</li>
3398</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3399
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3400<p>So the roadmap to upgrade your existing libxml applications is the
3401following:</p>
3402<ol>
3403 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3404 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3405 used and change it to <strong>xmlRootNode</strong></li>
3406 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3407 field is used and change it to <strong>xmlChildrenNode</strong></li>
3408 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3409 <strong>main()</strong> or in the library init entry point</li>
3410 <li>Recompile, check compatibility, it should still work</li>
3411 <li>Change your configure script to look first for xml2-config and fallback
3412 using xml-config . Use the --cflags and --libs ouptut of the command as
3413 the Include and Linking parameters needed to use libxml.</li>
3414 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3415 libxml-devel-1.8.y can be kept simultaneously)</li>
3416 <li>remove your config.cache, relaunch your configuration mechanism, and
3417 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3418 <li>Test that your application is still running correctly, if not this may
3419 be due to extra empty nodes due to formating spaces being kept in libxml2
3420 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3421 code before calling the parser (next to
3422 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3423</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3424
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3425<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]3426
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3427<p>Let me put some emphasis on the fact that there is far more changes from
3428libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3429has been considerably cleaned up and the conformance to the XML specification
3430has been drastically improved too. Don't take those changes as an excuse to
3431not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3432
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3433<h2><a name="Thread">Thread safety</a></h2>
3434
3435<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3436threads can safely work in parallel parsing different documents. There is
3437however a couple of things to do to ensure it:</p>
3438<ul>
3439 <li>configure the library accordingly using the --with-threads options</li>
3440 <li>call xmlInitParser() in the "main" thread before using any of the
3441 libxml API (except possibly selecting a different memory allocator)</li>
3442</ul>
3443
3444<p>Note that the thread safety cannot be ensured for multiple threads sharing
3445the same document, the locking must be done at the application level, libxml
3446exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3447The parts of the library checked for thread safety are:</p>
3448<ul>
3449 <li>concurrent loading</li>
3450 <li>file access resolution</li>
3451 <li>catalog access</li>
3452 <li>catalog building</li>
3453 <li>entities lookup/accesses</li>
3454 <li>validation</li>
3455 <li>global variables per-thread override</li>
3456 <li>memory handling</li>
3457</ul>
3458
3459<p>XPath is supposed to be thread safe now, but this wasn't tested
3460seriously.</p>
3461
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3462<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3463
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3464<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3465Object Model</em>; this is an API for accessing XML or HTML structured
3466documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3467and will be based on gnome-xml. This will be a far cleaner interface to
3468manipulate XML files within Gnome since it won't expose the internal
3469structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3470
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3471<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3472href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3473is a full DOM interface, thanks to Paolo Casarini, check the <a
3474href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3475informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3476
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3477<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3478
3479<p>Here is a real size example, where the actual content of the application
3480data 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]3481a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3482storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3483base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3484<pre>&lt;?xml version="1.0"?&gt;
3485&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3486 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3487
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3488 &lt;gjob:Job&gt;
3489 &lt;gjob:Project ID="3"/&gt;
3490 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3491 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3492
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3493 &lt;gjob:Update&gt;
3494 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3495 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3496 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3497 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3498
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3499 &lt;gjob:Developers&gt;
3500 &lt;gjob:Developer&gt;
3501 &lt;/gjob:Developer&gt;
3502 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3503
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3504 &lt;gjob:Contact&gt;
3505 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3506 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3507 &lt;gjob:Company&gt;
3508 &lt;/gjob:Company&gt;
3509 &lt;gjob:Organisation&gt;
3510 &lt;/gjob:Organisation&gt;
3511 &lt;gjob:Webpage&gt;
3512 &lt;/gjob:Webpage&gt;
3513 &lt;gjob:Snailmail&gt;
3514 &lt;/gjob:Snailmail&gt;
3515 &lt;gjob:Phone&gt;
3516 &lt;/gjob:Phone&gt;
3517 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3518
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 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3521 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3522
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3523 &lt;gjob:Skills&gt;
3524 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3525
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3526 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3527 A GNOME based system that will allow a superuser to configure
3528 compressed and uncompressed files and/or file systems to be backed
3529 up with a supported media in the system. This should be able to
3530 perform via find commands generating a list of files that are passed
3531 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3532 or via operations performed on the filesystem itself. Email
3533 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3534 &lt;/gjob:Details&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:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3537
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3538 &lt;/gjob:Jobs&gt;
3539&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3540
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3541<p>While loading the XML file into an internal DOM tree is a matter of
3542calling only a couple of functions, browsing the tree to gather the ata and
3543generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3544
3545<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3546structure. For example, the ordering of the attributes is not significant,
3547the 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]3548depend on the order of the children of a given node, unless it really makes
3549things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3550<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3551 * A person record
3552 */
3553typedef struct person {
3554 char *name;
3555 char *email;
3556 char *company;
3557 char *organisation;
3558 char *smail;
3559 char *webPage;
3560 char *phone;
3561} person, *personPtr;
3562
3563/*
3564 * And the code needed to parse it
3565 */
3566personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3567 personPtr ret = NULL;
3568
3569DEBUG("parsePerson\n");
3570 /*
3571 * allocate the struct
3572 */
3573 ret = (personPtr) malloc(sizeof(person));
3574 if (ret == NULL) {
3575 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3576 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3577 }
3578 memset(ret, 0, sizeof(person));
3579
3580 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3581 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3582 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3583 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3584 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3585 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3586 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3587 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3588 }
3589
3590 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3591}</pre>
3592
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3593<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3594<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3595 <li>Usually a recursive parsing style is the more convenient one: XML data
3596 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3597 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3598 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3599 i.e. the pointer to the global XML document and the namespace reserved to
3600 the application. Document wide information are needed for example to
3601 decode entities and it's a good coding practice to define a namespace for
3602 your application set of data and test that the element and attributes
3603 you're analyzing actually pertains to your application space. This is
3604 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3605 <li>To retrieve text and attributes value, you can use the function
3606 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3607 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3608</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3609
3610<p>Here is another piece of code used to parse another level of the
3611structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3612<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3613/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3614 * a Description for a Job
3615 */
3616typedef struct job {
3617 char *projectID;
3618 char *application;
3619 char *category;
3620 personPtr contact;
3621 int nbDevelopers;
3622 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3623} job, *jobPtr;
3624
3625/*
3626 * And the code needed to parse it
3627 */
3628jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3629 jobPtr ret = NULL;
3630
3631DEBUG("parseJob\n");
3632 /*
3633 * allocate the struct
3634 */
3635 ret = (jobPtr) malloc(sizeof(job));
3636 if (ret == NULL) {
3637 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3638 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3639 }
3640 memset(ret, 0, sizeof(job));
3641
3642 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3643 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3644 while (cur != NULL) {
3645
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3646 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3647 ret-&gt;projectID = xmlGetProp(cur, "ID");
3648 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3649 fprintf(stderr, "Project has no ID\n");
3650 }
3651 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3652 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3653 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3654 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3655 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3656 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3657 ret-&gt;contact = parsePerson(doc, ns, cur);
3658 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3659 }
3660
3661 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3662}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3663
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3664<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]3665boring. Ultimately, it could be possble to write stubbers taking either C
3666data structure definitions, a set of XML examples or an XML DTD and produce
3667the code needed to import and export the content between C data and XML
3668storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3669
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3670<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3671parsing example</a> as a template, it is also available with Makefile in the
3672Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3673
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3674<h2><a name="Contributi">Contributions</a></h2>
3675<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3676 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3677 patches, Gary Pennington worked on the validation API, threading support
3678 and Solaris port.</li>
3679 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3680 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
3681 for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3682 Website: <a
3683 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3684 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3685 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]3686 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the
3687 maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3688 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3689 provides binaries</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3690 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides
3691 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3692 <li><a
3693 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3694 Sergeant</a> developped <a
3695 href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
3696 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
3697 application server</a></li>
3698 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a
3699 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3700 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3701 documentation</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3702 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
3703 href="http://xmlsoft.org/messages/0488.html">man pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3704 <li>there is a module for <a
3705 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3706 in OpenNSD/AOLServer</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]3707 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides
3708 libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for
3709 Python</a></li>
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]3710 <li>Petr Kozelka provides <a
3711 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
3712 libxml2</a> with Kylix and Delphi and other Pascal compilers</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3713</ul>
3714
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3715<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3716</body>
3717</html>