Gitiles
Code Review Sign In
gerrit-public.fairphone.software / platform / external / libxml2 / b9e469a12199606f4037aeeef8246f64ac995377 / . / doc / xml.html
blob: 70e024b92150aab661d182a020f5a780b9062cf1 [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 Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V5.0">
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>
35 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]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 Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]53</ul>
54
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]55<p>In most cases libxml tries to implement the specifications in a relatively
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]56strict way. As of release 2.4.16, libxml2 passes all 1800+ tests from the <a
57href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests
58Suite</a>.</p>
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]59
60<p>To some extent libxml2 provide some support for the following other
61specification but don't claim to implement them:</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]62<ul>
63 <li>Document Object Model (DOM) <a
64 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
65 it doesn't implement the API itself, gdome2 does this in top of
66 libxml2</li>
67 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]68 : libxml implements a basic FTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]69 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]70 : HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]71 <li>SAX: a minimal SAX implementation compatible with early expat
72 versions</li>
73 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
74 XML</li>
75</ul>
76
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]77<p>Libxml2 is known to be very portable, should build and work without
78serious troubles on a variety of systems (Linux, Unix, Windows, CygWin,
79MacOs, MacOsX, RISC Os, OS/2, VMS, QNX, MVS, ...)</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]80
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]81<p>Separate documents:</p>
82<ul>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]83 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a>
84 providing an implementation of XSLT 1.0 and extensions on top of
85 libxml2</li>
86 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]87 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]88</ul>
89
90<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]91
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]92<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]93href="http://www.w3.org/XML/">XML</a> C library developped for the <a
94href="http://www.gnome.org/">Gnome</a> project. <a
95href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
96structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]97
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]98<p>Here are some key points about libxml:</p>
99<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]100 <li>Libxml exports Push and Pull type parser interfaces for both XML and
101 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]102 <li>Libxml can do DTD validation at parse time, using a parsed document
103 instance, or with an arbitrary DTD.</li>
104 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]105 href="http://www.w3.org/TR/xpath">XPath</a>, <a
106 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
107 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]108 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]109 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]110 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]111 <li>Basic support for HTTP and FTP client allowing aplications to fetch
112 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]113 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]114 <li>The internal document repesentation is as close as possible to the <a
115 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
116 <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]117 like interface</a>; the interface is designed to be compatible with <a
118 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]119 <li>This library is released under the <a
120 href="http://www.opensource.org/licenses/mit-license.html">MIT
121 Licence</a> see the Copyright file in the distribution for the precise
122 wording.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]123</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]124
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]125<p>Warning: unless you are forced to because your application links with a
126Gnome library requiring it, <strong><span
127style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
128libxml2</p>
129
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]130<h2><a name="FAQ">FAQ</a></h2>
131
132<p>Table of Content:</p>
133<ul>
134 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
135 <li><a href="FAQ.html#Installati">Installation</a></li>
136 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
137 <li><a href="FAQ.html#Developer">Developer corner</a></li>
138</ul>
139
140<h3><a name="Licence">Licence</a>(s)</h3>
141<ol>
142 <li><em>Licensing Terms for libxml</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]143 <p>libxml is released under the <a
144 href="http://www.opensource.org/licenses/mit-license.html">MIT
145 Licence</a>, see the file Copyright in the distribution for the precise
146 wording</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]147 </li>
148 <li><em>Can I embed libxml in a proprietary application ?</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]149 <p>Yes. The MIT Licence allows you to also keep proprietary the changes
150 you made to libxml, but it would be graceful to provide back bugfixes and
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]151 improvements as patches for possible incorporation in the main
152 development tree</p>
153 </li>
154</ol>
155
156<h3><a name="Installati">Installation</a></h3>
157<ol>
158 <li>Unless you are forced to because your application links with a Gnome
159 library requiring it, <strong><span style="background-color: #FF0000">Do
160 Not Use libxml1</span></strong>, use libxml2</li>
161 <li><em>Where can I get libxml</em>
162 ?
163 <p>The original distribution comes from <a
164 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
165 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
166 <p>Most linux and Bsd distribution includes libxml, this is probably the
167 safer way for end-users</p>
168 <p>David Doolin provides precompiled Windows versions at <a
169 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
170 </li>
171 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
172 <ul>
173 <li>If you are not concerned by any existing backward compatibility
174 with existing application, install libxml2 only</li>
175 <li>If you are not doing development, you can safely install both.
176 usually the packages <a
177 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
178 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
179 compatible (this is not the case for development packages)</li>
180 <li>If you are a developer and your system provides separate packaging
181 for shared libraries and the development components, it is possible
182 to install libxml and libxml2, and also <a
183 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
184 and <a
185 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
186 too for libxml2 &gt;= 2.3.0</li>
187 <li>If you are developing a new application, please develop against
188 libxml2(-devel)</li>
189 </ul>
190 </li>
191 <li><em>I can't install the libxml package it conflicts with libxml0</em>
192 <p>You probably have an old libxml0 package used to provide the shared
193 library for libxml.so.0, you can probably safely remove it. Anyway the
194 libxml packages provided on <a
195 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
196 libxml.so.0</p>
197 </li>
198 <li><em>I can't install the libxml(2) RPM package due to failed
199 dependancies</em>
200 <p>The most generic solution is to refetch the latest src.rpm , and
201 rebuild it locally with</p>
202 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
203 <p>if everything goes well it will generate two binary rpm (one providing
204 the shared libs and xmllint, and the other one, the -devel package
205 providing includes, static libraries and scripts needed to build
206 applications with libxml(2)) that you can install locally.</p>
207 </li>
208</ol>
209
210<h3><a name="Compilatio">Compilation</a></h3>
211<ol>
212 <li><em>What is the process to compile libxml ?</em>
213 <p>As most UNIX libraries libxml follows the "standard":</p>
214 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
215 <p><code>cd libxml-xxxx</code></p>
216 <p><code>./configure --help</code></p>
217 <p>to see the options, then the compilation/installation proper</p>
218 <p><code>./configure [possible options]</code></p>
219 <p><code>make</code></p>
220 <p><code>make install</code></p>
221 <p>At that point you may have to rerun ldconfig or similar utility to
222 update your list of installed shared libs.</p>
223 </li>
224 <li><em>What other libraries are needed to compile/install libxml ?</em>
225 <p>Libxml does not requires any other library, the normal C ANSI API
226 should be sufficient (please report any violation to this rule you may
227 find).</p>
228 <p>However if found at configuration time libxml will detect and use the
229 following libs:</p>
230 <ul>
231 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
232 : a highly portable and available widely compression library</li>
233 <li>iconv: a powerful character encoding conversion library. It's
234 included by default on recent glibc libraries, so it doesn't need to
235 be installed specifically on linux. It seems it's now <a
236 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
237 of the official UNIX</a> specification. Here is one <a
238 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
239 of the library</a> which source can be found <a
240 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
241 </ul>
242 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]243 <li><em>make check fails on some platforms</em>
244 <p>Sometime the regression tests results don't completely match the value
245 produced by the parser, and the makefile uses diff to print the delta. On
246 some platforms the diff return breaks the compilation process, if the
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]247 diff is small this is probably not a serious problem.</p>
248 <p>Sometimes (especially on Solaris) make checks fails due to limitations
249 in make. Try using GNU-make instead.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]250 </li>
251 <li><em>I use the CVS version and there is no configure script</em>
252 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
253 script to regenerate the configure and Makefiles, like:</p>
254 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
255 </li>
256 <li><em>I have troubles when running make tests with gcc-3.0</em>
257 <p>It seems the initial release of gcc-3.0 has a problem with the
258 optimizer which miscompiles the URI module. Please use another
259 compiler</p>
260 </li>
261</ol>
262
263<h3><a name="Developer">Developer</a> corner</h3>
264<ol>
265 <li><em>xmlDocDump() generates output on one line</em>
266 <p>libxml will not <strong>invent</strong> spaces in the content of a
267 document since <strong>all spaces in the content of a document are
268 significant</strong>. If you build a tree from the API and want
269 indentation:</p>
270 <ol>
271 <li>the correct way is to generate those yourself too</li>
272 <li>the dangerous way is to ask libxml to add those blanks to your
273 content <strong>modifying the content of your document in the
274 process</strong>. The result may not be what you expect. There is
275 <strong>NO</strong> way to guarantee that such a modification won't
276 impact other part of the content of your document. See <a
277 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
278 ()</a> and <a
279 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
280 ()</a></li>
281 </ol>
282 </li>
283 <li>Extra nodes in the document:
284 <p><em>For a XML file as below:</em></p>
285 <pre>&lt;?xml version="1.0"?&gt;
286&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
287&lt;NODE CommFlag="0"/&gt;
288&lt;NODE CommFlag="1"/&gt;
289&lt;/PLAN&gt;</pre>
290 <p><em>after parsing it with the function
291 pxmlDoc=xmlParseFile(...);</em></p>
292 <p><em>I want to the get the content of the first node (node with the
293 CommFlag="0")</em></p>
294 <p><em>so I did it as following;</em></p>
295 <pre>xmlNodePtr pode;
296pnode=pxmlDoc-&gt;children-&gt;children;</pre>
297 <p><em>but it does not work. If I change it to</em></p>
298 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
299 <p><em>then it works. Can someone explain it to me.</em></p>
300 <p></p>
301 <p>In XML all characters in the content of the document are significant
302 <strong>including blanks and formatting line breaks</strong>.</p>
303 <p>The extra nodes you are wondering about are just that, text nodes with
304 the formatting spaces wich are part of the document but that people tend
305 to forget. There is a function <a
306 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
307 ()</a> to remove those at parse time, but that's an heuristic, and its
308 use should be limited to case where you are sure there is no
309 mixed-content in the document.</p>
310 </li>
311 <li><em>I get compilation errors of existing code like when accessing
312 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
313 <p>You are compiling code developed for libxml version 1 and using a
314 libxml2 development environment. Either switch back to libxml v1 devel or
315 even better fix the code to compile with libxml2 (or both) by <a
316 href="upgrade.html">following the instructions</a>.</p>
317 </li>
318 <li><em>I get compilation errors about non existing
319 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
320 fields</em>
321 <p>The source code you are using has been <a
322 href="upgrade.html">upgraded</a> to be able to compile with both libxml
323 and libxml2, but you need to install a more recent version:
324 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
325 </li>
326 <li><em>XPath implementation looks seriously broken</em>
327 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
328 a recent version, the implementation and debug of libxslt generated fixes
329 for most obvious problems.</p>
330 </li>
331 <li><em>The example provided in the web page does not compile</em>
332 <p>It's hard to maintain the documentation in sync with the code
333 &lt;grin/&gt; ...</p>
334 <p>Check the previous points 1/ and 2/ raised before, and send
335 patches.</p>
336 </li>
337 <li><em>Where can I get more examples and informations than in the web
338 page</em>
339 <p>Ideally a libxml book would be nice. I have no such plan ... But you
340 can:</p>
341 <ul>
342 <li>check more deeply the <a href="html/libxml-lib.html">existing
343 generated doc</a></li>
344 <li>looks for examples of use for libxml function using the Gnome code
345 for example the following will query the full Gnome CVs base for the
346 use of the <strong>xmlAddChild()</strong> function:
347 <p><a
348 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
349 <p>This may be slow, a large hardware donation to the gnome project
350 could cure this :-)</p>
351 </li>
352 <li><a
353 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
354 the libxml source</a>
355 , I try to write code as clean and documented as possible, so
356 looking at it may be helpful</li>
357 </ul>
358 </li>
359 <li>What about C++ ?
360 <p>libxml is written in pure C in order to allow easy reuse on a number
361 of platforms, including embedded systems. I don't intend to convert to
362 C++.</p>
363 <p>There is however a C++ wrapper provided by Ari Johnson
364 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
365 <p>Website: <a
366 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
367 <p>Download: <a
368 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
369 </li>
370 <li>How to validate a document a posteriori ?
371 <p>It is possible to validate documents which had not been validated at
372 initial parsing time or documents who have been built from scratch using
373 the API. Use the <a
374 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
375 function. It is also possible to simply add a Dtd to an existing
376 document:</p>
377 <pre>xmlDocPtr doc; /* your existing document */
378 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
379 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
380
381 doc-&gt;intSubset = dtd;
382 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
383 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
384 </pre>
385 </li>
386 <li>etc ...</li>
387</ol>
388
389<p></p>
390
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]391<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]392
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]393<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]394<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]395 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]396 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]397 documentation</a> automatically extracted from code comments (using <a
398 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
399 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]400 <li>Look at the documentation about <a href="encoding.html">libxml
401 internationalization support</a></li>
Daniel Veillardbc66f852002-01-14 09:49:20 +0000[diff] [blame]402 <li>This page provides a global overview and <a href="example.html">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]403 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]404 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
405 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]406 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
407 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]408 <li>George Lebl wrote <a
409 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]410 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]411 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
412 file</a></li>
413 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
414 starting a new project using libxml you should really use the 2.x
415 version.</li>
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]416 <li>And don't forget to look at the <a
417 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]418</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]419
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]420<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]421
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]422<p>Well, bugs or missing features are always possible, and I will make a
423point of fixing them in a timely fashion. The best way to report a bug is to
424use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
425bug tracking database</a> (make sure to use the "libxml" module name). I look
426at 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]427still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]428
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]429<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]430href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
431href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]432href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
433please visit the <a
434href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
435follow the instructions. <strong>Do not send code, I won't debug it</strong>
436(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]437
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]438<p>Check the following <strong><span style="color: #FF0000">before
439posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]440<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]441 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]442 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
443 version</a>, and that the problem still shows up in those</li>
444 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
445 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]446 there is probably a fix available, similary check the <a
447 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]448 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]449 <li>make sure you can reproduce the bug with xmllint or one of the test
450 programs found in source in the distribution</li>
451 <li>Please send the command showing the error as well as the input (as an
452 attachement)</li>
453</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]454
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]455<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]456href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]457related I will approve it.. Please do not send me mail directly, it makes
458things really harder to track and in some cases I'm not the best person to
459answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]460
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]461<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]462probably be processed faster.</p>
463
464<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]465href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]466provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]467questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]468documentantion</a> is not as polished as I would like (i need to learn more
469about Docbook), but it's a good starting point.</p>
470
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]471<h2><a name="help">How to help</a></h2>
472
473<p>You can help the project in various ways, the best thing to do first is to
474subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]475href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
476href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]477database:</a>:</p>
478<ol>
479 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]480 <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]481 be integrated in all cases but help pinpointing portability problems
482 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]483 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]484 as HTML diffs).</li>
485 <li>provide new documentations pieces (translations, examples, etc ...)</li>
486 <li>Check the TODO file and try to close one of the items</li>
487 <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]488 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
489 </a>before to avoid synchronization problems and check that the suggested
490 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]491</ol>
492
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]493<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]494
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]495<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]496href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
497href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
498href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]499href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]500as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]501archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]502href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
503packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]504href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
505href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]506packages installed to compile applications using libxml.) <a
507href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
508of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]509href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]510provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]511Pennington</a> provides <a href="http://garypennington.net/libxml2/">Solaris
512binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]513
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]514<p><a name="Snapshot">Snapshot:</a></p>
515<ul>
516 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]517 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]518 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]519 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]520</ul>
521
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]522<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]523
524<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]525platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]526languages have been provided, and can be found in the <a
527href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]528
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]529<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]530<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]531 <li><p>The <a
532 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]533 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]534 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
535 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]536 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]537 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]538</ul>
539
540<h2><a name="News">News</a></h2>
541
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]542<h3>CVS only : check the <a
543href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]544for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]545
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]546<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]547you want to test those</p>
548<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]549 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
550 as a separate C library on top of libxml called libxslt</li>
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 Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]553 <li>(seeems working but delayed from release) parsing/import of Docbook
554 SGML docs</li>
555</ul>
556
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]557<h3>2.4.16: Feb 20 2002</h3>
558<ul>
559 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite
560 from OASIS and W3C. Compliance has been significantly improved.</li>
561 <li>a couple of portability fixes too.</li>
562</ul>
563
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]564<h3>2.4.15: Feb 11 2002</h3>
565<ul>
566 <li>Fixed the Makefiles, especially the python module ones</li>
567 <li>A few bug fixes and cleanup</li>
568 <li>Includes cleanup</li>
569</ul>
570
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]571<h3>2.4.14: Feb 8 2002</h3>
572<ul>
573 <li>Change of Licence to the <a
574 href="http://www.opensource.org/licenses/mit-license.html">MIT
575 Licence</a> basisally for integration in XFree86 codebase, and removing
576 confusion around the previous dual-licencing</li>
577 <li>added Python bindings, beta software but should already be quite
578 complete</li>
579 <li>a large number of fixes and cleanups, especially for all tree
580 manipulations</li>
581 <li>cleanup of the headers, generation of a reference API definition in
582 XML</li>
583</ul>
584
585<h3>2.4.13: Jan 14 2002</h3>
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]586<ul>
587 <li>update of the documentation: John Fleck and Charlie Bozeman</li>
588 <li>cleanup of timing code from Justin Fletcher</li>
589 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei
590 Narojnyi</li>
591 <li>Cygwin patch from Robert Collins</li>
592 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li>
593</ul>
594
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]595<h3>2.4.12: Dec 7 2001</h3>
596<ul>
597 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman),
598 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups
599 (robert)</li>
600 <li>Eric Lavigne contributed project files for MacOS</li>
601 <li>some makefiles cleanups</li>
602</ul>
603
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]604<h3>2.4.11: Nov 26 2001</h3>
605<ul>
606 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
607 cleanups</li>
608 <li>xmllint man pages improvement by Heiko Rupp</li>
609 <li>updated VMS build instructions from John A Fotheringham</li>
610 <li>Windows Makefiles updates from Igor</li>
611</ul>
612
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]613<h3>2.4.10: Nov 10 2001</h3>
614<ul>
615 <li>URI escaping fix (Joel Young)</li>
616 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
617 <li>Fixes namespace handling problems when using DTD and validation</li>
618 <li>improvements on xmllint: Morus Walter patches for --format and
619 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
620 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
621 <li>fixes to the HTML parser</li>
622</ul>
623
624<h3>2.4.9: Nov 6 2001</h3>
625<ul>
626 <li>fixes more catalog bugs</li>
627 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
628</ul>
629
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]630<h3>2.4.8: Nov 4 2001</h3>
631<ul>
632 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
633 tool</li>
634 <li>fixed a compile errors and some includes troubles.</li>
635</ul>
636
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]637<h3>2.4.7: Oct 30 2001</h3>
638<ul>
639 <li>exported some debugging interfaces</li>
640 <li>serious rewrite of the catalog code</li>
641 <li>integrated Gary Pennington thread safety patch, added configure option
642 and regression tests</li>
643 <li>removed an HTML parser bug</li>
644 <li>fixed a couple of potentially serious validation bugs</li>
645 <li>integrated the SGML DocBook support in xmllint</li>
646 <li>changed the nanoftp anonymous login passwd</li>
647 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
648 <li>general bug fixes</li>
649 <li>updated xmllint man page by John Fleck</li>
650 <li>some VMS and Windows updates</li>
651</ul>
652
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]653<h3>2.4.6: Oct 10 2001</h3>
654<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]655 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]656 <li>portability and configure fixes</li>
657 <li>an infinite loop on the HTML parser was removed (William)</li>
658 <li>Windows makefile patches from Igor</li>
659 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
660 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
661</ul>
662
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]663<h3>2.4.5: Sep 14 2001</h3>
664<ul>
665 <li>Remove a few annoying bugs in 2.4.4</li>
666 <li>forces the HTML serializer to output decimal charrefs since some
667 version of Netscape can't handle hexadecimal ones</li>
668</ul>
669
670<h3>1.8.16: Sep 14 2001</h3>
671<ul>
672 <li>maintenance release of the old libxml1 branch, couple of bug and
673 portability fixes</li>
674</ul>
675
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]676<h3>2.4.4: Sep 12 2001</h3>
677<ul>
678 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
679 Catalog</li>
680 <li>a few bug fixes and some portability changes</li>
681 <li>some documentation cleanups</li>
682</ul>
683
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]684<h3>2.4.3: Aug 23 2001</h3>
685<ul>
686 <li>XML Catalog support see the doc</li>
687 <li>New NaN/Infinity floating point code</li>
688 <li>A few bug fixes</li>
689</ul>
690
691<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]692<ul>
693 <li>adds xmlLineNumbersDefault() to control line number generation</li>
694 <li>lot of bug fixes</li>
695 <li>the Microsoft MSC projects files shuld now be up to date</li>
696 <li>inheritance of namespaces from DTD defaulted attributes</li>
697 <li>fixes a serious potential security bug</li>
698 <li>added a --format option to xmllint</li>
699</ul>
700
701<h3>2.4.1: July 24 2001</h3>
702<ul>
703 <li>possibility to keep line numbers in the tree</li>
704 <li>some computation NaN fixes</li>
705 <li>extension of the XPath API</li>
706 <li>cleanup for alpha and ia64 targets</li>
707 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]708</ul>
709
710<h3>2.4.0: July 10 2001</h3>
711<ul>
712 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
713 <li>Fixed XML Base implementation, added a coupel of examples to the
714 regression tests</li>
715 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]716</ul>
717
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]718<h3>2.3.14: July 5 2001</h3>
719<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]720 <li>fixed some entities problems and reduce mem requirement when
721 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]722 <li>lots of improvements in the XPath queries interpreter can be
723 substancially faster</li>
724 <li>Makefiles and configure cleanups</li>
725 <li>Fixes to XPath variable eval, and compare on empty node set</li>
726 <li>HTML tag closing bug fixed</li>
727 <li>Fixed an URI reference computating problem when validating</li>
728</ul>
729
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]730<h3>2.3.13: June 28 2001</h3>
731<ul>
732 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
733 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
734</ul>
735
736<h3>1.8.14: June 28 2001</h3>
737<ul>
738 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
739 <li>Small Makefile fix</li>
740</ul>
741
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]742<h3>2.3.12: June 26 2001</h3>
743<ul>
744 <li>lots of cleanup</li>
745 <li>a couple of validation fix</li>
746 <li>fixed line number counting</li>
747 <li>fixed serious problems in the XInclude processing</li>
748 <li>added support for UTF8 BOM at beginning of entities</li>
749 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
750 miscompile uri.c (William), Thomas Leitner provided a fix for the
751 optimizer on Tru64</li>
752 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
753 compilation on Windows MSC</li>
754 <li>update of libxml-doc.el (Felix Natter)</li>
755 <li>fixed 2 bugs in URI normalization code</li>
756</ul>
757
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]758<h3>2.3.11: June 17 2001</h3>
759<ul>
760 <li>updates to trio, Makefiles and configure should fix some portability
761 problems (alpha)</li>
762 <li>fixed some HTML serialization problems (pre, script, and block/inline
763 handling), added encoding aware APIs, cleanup of this code</li>
764 <li>added xmlHasNsProp()</li>
765 <li>implemented a specific PI for encoding support in the DocBook SGML
766 parser</li>
767 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
768 node selection)</li>
769 <li>fixed a performance problem and an error in the validation code</li>
770 <li>fixed XInclude routine to implement the recursive behaviour</li>
771 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
772 <li>added --version to xmllint for bug reports</li>
773</ul>
774
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]775<h3>2.3.10: June 1 2001</h3>
776<ul>
777 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]778 <li>a number of reported bugs got fixed, in XPath, iconv detection,
779 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]780 <li>XPath string function should now handle unicode correctly</li>
781</ul>
782
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]783<h3>2.3.9: May 19 2001</h3>
784
785<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
786<ul>
787 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
788 <li>some serious speed optimisation again</li>
789 <li>some documentation cleanups</li>
790 <li>trying to get better linking on solaris (-R)</li>
791 <li>XPath API cleanup from Thomas Broyer</li>
792 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
793 xmlValidGetValidElements()</li>
794 <li>Added an INSTALL file</li>
795 <li>Attribute removal added to API: #54433</li>
796 <li>added a basic support for SGML catalogs</li>
797 <li>fixed xmlKeepBlanksDefault(0) API</li>
798 <li>bugfix in xmlNodeGetLang()</li>
799 <li>fixed a small configure portability problem</li>
800 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
801</ul>
802
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]803<h3>1.8.13: May 14 2001</h3>
804<ul>
805 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
806</ul>
807
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]808<h3>2.3.8: May 3 2001</h3>
809<ul>
810 <li>Integrated an SGML DocBook parser for the Gnome project</li>
811 <li>Fixed a few things in the HTML parser</li>
812 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
813 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]814 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
815 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]816 <li>incorporated more Windows cleanup</li>
817 <li>added xmlSaveFormatFile()</li>
818 <li>fixed problems in copying nodes with entities references (gdome)</li>
819 <li>removed some troubles surrounding the new validation module</li>
820</ul>
821
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]822<h3>2.3.7: April 22 2001</h3>
823<ul>
824 <li>lots of small bug fixes, corrected XPointer</li>
825 <li>Non determinist content model validation support</li>
826 <li>added xmlDocCopyNode for gdome2</li>
827 <li>revamped the way the HTML parser handles end of tags</li>
828 <li>XPath: corrctions of namespacessupport and number formatting</li>
829 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
830 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
831 <li>Improved validation speed sensible for DocBook</li>
832 <li>fixed a big bug with ID declared in external parsed entities</li>
833 <li>portability fixes, update of Trio from Bjorn Reese</li>
834</ul>
835
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]836<h3>2.3.6: April 8 2001</h3>
837<ul>
838 <li>Code cleanup using extreme gcc compiler warning options, found and
839 cleared half a dozen potential problem</li>
840 <li>the Eazel team found an XML parser bug</li>
841 <li>cleaned up the user of some of the string formatting function. used the
842 trio library code to provide the one needed when the platform is missing
843 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]844 <li>xpath: removed a memory leak and fixed the predicate evaluation
845 problem, extended the testsuite and cleaned up the result. XPointer seems
846 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]847</ul>
848
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]849<h3>2.3.5: Mar 23 2001</h3>
850<ul>
851 <li>Biggest change is separate parsing and evaluation of XPath expressions,
852 there is some new APIs for this too</li>
853 <li>included a number of bug fixes(XML push parser, 51876, notations,
854 52299)</li>
855 <li>Fixed some portability issues</li>
856</ul>
857
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]858<h3>2.3.4: Mar 10 2001</h3>
859<ul>
860 <li>Fixed bugs #51860 and #51861</li>
861 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
862 size to be application tunable.</li>
863 <li>Some cleanup in the validation code, still a bug left and this part
864 should probably be rewritten to support ambiguous content model :-\</li>
865 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
866 parser</li>
867 <li>Fixed another bug in xmlNodeGetContent()</li>
868 <li>Bjorn fixed XPath node collection and Number formatting</li>
869 <li>Fixed a loop reported in the HTML parsing</li>
870 <li>blank space are reported even if the Dtd content model proves that they
871 are formatting spaces, this is for XmL conformance</li>
872</ul>
873
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]874<h3>2.3.3: Mar 1 2001</h3>
875<ul>
876 <li>small change in XPath for XSLT</li>
877 <li>documentation cleanups</li>
878 <li>fix in validation by Gary Pennington</li>
879 <li>serious parsing performances improvements</li>
880</ul>
881
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]882<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]883<ul>
884 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
885 <li>fixed a Dtd parsing bug</li>
886 <li>fixed a bug in xmlNodeGetContent</li>
887 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
888</ul>
889
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]890<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]891<ul>
892 <li>some XPath and HTML bug fixes for XSLT</li>
893 <li>small extension of the hash table interfaces for DOM gdome2
894 implementation</li>
895 <li>A few bug fixes</li>
896</ul>
897
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]898<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]899<ul>
900 <li>Lots of XPath bug fixes</li>
901 <li>Add a mode with Dtd lookup but without validation error reporting for
902 XSLT</li>
903 <li>Add support for text node without escaping (XSLT)</li>
904 <li>bug fixes for xmlCheckFilename</li>
905 <li>validation code bug fixes from Gary Pennington</li>
906 <li>Patch from Paul D. Smith correcting URI path normalization</li>
907 <li>Patch to allow simultaneous install of libxml-devel and
908 libxml2-devel</li>
909 <li>the example Makefile is now fixed</li>
910 <li>added HTML to the RPM packages</li>
911 <li>tree copying bugfixes</li>
912 <li>updates to Windows makefiles</li>
913 <li>optimisation patch from Bjorn Reese</li>
914</ul>
915
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]916<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]917<ul>
918 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
919 <li>added htmlHandleOmittedElem()</li>
920 <li>Applied Bjorn Reese's IPV6 first patch</li>
921 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]922 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]923</ul>
924
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]925<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]926<ul>
927 <li>Fix the Windows problems of 2.2.8</li>
928 <li>integrate OpenVMS patches</li>
929 <li>better handling of some nasty HTML input</li>
930 <li>Improved the XPointer implementation</li>
931 <li>integrate a number of provided patches</li>
932</ul>
933
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]934<h3>2.2.9: Nov 25 2000</h3>
935<ul>
936 <li>erroneous release :-(</li>
937</ul>
938
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]939<h3>2.2.8: Nov 13 2000</h3>
940<ul>
941 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
942 support</li>
943 <li>Patch in conditional section handling</li>
944 <li>updated MS compiler project</li>
945 <li>fixed some XPath problems</li>
946 <li>added an URI escaping function</li>
947 <li>some other bug fixes</li>
948</ul>
949
950<h3>2.2.7: Oct 31 2000</h3>
951<ul>
952 <li>added message redirection</li>
953 <li>XPath improvements (thanks TOM !)</li>
954 <li>xmlIOParseDTD() added</li>
955 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
956 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
957</ul>
958
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]959<h3>2.2.6: Oct 25 2000:</h3>
960<ul>
961 <li>Added an hash table module, migrated a number of internal structure to
962 those</li>
963 <li>Fixed a posteriori validation problems</li>
964 <li>HTTP module cleanups</li>
965 <li>HTML parser improvements (tag errors, script/style handling, attribute
966 normalization)</li>
967 <li>coalescing of adjacent text nodes</li>
968 <li>couple of XPath bug fixes, exported the internal API</li>
969</ul>
970
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]971<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]972<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]973 <li>XPointer implementation and testsuite</li>
974 <li>Lot of XPath fixes, added variable and functions registration, more
975 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]976 <li>Portability fixes, lots of enhancements toward an easy Windows build
977 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]978 <li>Late validation fixes</li>
979 <li>Integrated a lot of contributed patches</li>
980 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]981 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]982</ul>
983
984<h3>2.2.4: Oct 1 2000:</h3>
985<ul>
986 <li>main XPath problem fixed</li>
987 <li>Integrated portability patches for Windows</li>
988 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]989</ul>
990
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]991<h3>2.2.3: Sep 17 2000</h3>
992<ul>
993 <li>bug fixes</li>
994 <li>cleanup of entity handling code</li>
995 <li>overall review of all loops in the parsers, all sprintf usage has been
996 checked too</li>
997 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
998 works smoothly now.</li>
999</ul>
1000
1001<h3>1.8.10: Sep 6 2000</h3>
1002<ul>
1003 <li>bug fix release for some Gnome projects</li>
1004</ul>
1005
1006<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1007<ul>
1008 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]1009 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1010</ul>
1011
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1012<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1013<ul>
1014 <li>a purely bug fixes release</li>
1015 <li>fixed an encoding support problem when parsing from a memory block</li>
1016 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1017 <li>removed a bug in the function allowing to override the memory
1018 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1019</ul>
1020
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1021<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]1022<ul>
1023 <li>applied a lot of portability fixes</li>
1024 <li>better encoding support/cleanup and saving (content is now always
1025 encoded in UTF-8)</li>
1026 <li>the HTML parser now correctly handles encodings</li>
1027 <li>added xmlHasProp()</li>
1028 <li>fixed a serious problem with &amp;#38;</li>
1029 <li>propagated the fix to FTP client</li>
1030 <li>cleanup, bugfixes, etc ...</li>
1031 <li>Added a page about <a href="encoding.html">libxml Internationalization
1032 support</a></li>
1033</ul>
1034
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1035<h3>1.8.9: July 9 2000</h3>
1036<ul>
1037 <li>fixed the spec the RPMs should be better</li>
1038 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
1039 rpmfind users problem</li>
1040</ul>
1041
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]1042<h3>2.1.1: July 1 2000</h3>
1043<ul>
1044 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1045 <li>improvements on the HTML parser</li>
1046</ul>
1047
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1048<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1049<ul>
1050 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1051 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1052 about &amp;#38; charref parsing</li>
1053 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1054 also contains numerous fixes and enhancements:
1055 <ul>
1056 <li>added xmlStopParser() to stop parsing</li>
1057 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1058 <li>includes XPath patches provided by Picdar Technology</li>
1059 <li>tried to fix as much as possible DtD validation and namespace
1060 related problems</li>
1061 <li>output to a given encoding has been added/tested</li>
1062 <li>lot of various fixes</li>
1063 </ul>
1064 </li>
1065</ul>
1066
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1067<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1068<ul>
1069 <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]1070 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1071 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1072 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1073 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1074 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1075 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1076 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1077 <pre>#include "xxx.h"</pre>
1078 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1079 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1080 <li>the memory allocation routines used by libxml can now be overloaded
1081 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1082 <li>The previously CVS only tool tester has been renamed
1083 <strong>xmllint</strong> and is now installed as part of the libxml2
1084 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1085 <li>The I/O interface has been revamped. There is now ways to plug in
1086 specific I/O modules, either at the URI scheme detection level using
1087 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1088 parser context using xmlCreateIOParserCtxt()</li>
1089 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1090 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1091 <li>a number of optional features of libxml can now be excluded at
1092 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1093</ul>
1094
1095<h3>2.0.0beta: Mar 14 2000</h3>
1096<ul>
1097 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1098 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1099 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1100 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1101 <li>This version is now the head in the Gnome CVS base, the old one is
1102 available under the tag LIB_XML_1_X</li>
1103 <li>This includes a very large set of changes. Froma programmatic point of
1104 view applications should not have to be modified too much, check the <a
1105 href="upgrade.html">upgrade page</a></li>
1106 <li>Some interfaces may changes (especially a bit about encoding).</li>
1107 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1108 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1109 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1110 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1111 <li>Better handling of entities, especially well formedness checking
1112 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1113 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1114 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1115 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1116 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1117 </ul>
1118 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1119 <li>Serious progress were made toward compliance, <a
1120 href="conf/result.html">here are the result of the test</a> against the
1121 OASIS testsuite (except the japanese tests since I don't support that
1122 encoding yet). This URL is rebuilt every couple of hours using the CVS
1123 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1124</ul>
1125
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1126<h3>1.8.7: Mar 6 2000</h3>
1127<ul>
1128 <li>This is a bug fix release:</li>
1129 <li>It is possible to disable the ignorable blanks heuristic used by
1130 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1131 that for adherence to XML spec, this behaviour will be disabled by
1132 default in 2.x . The same function will allow to keep compatibility for
1133 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1134 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1135 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1136 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1137 compilation on some platforms has been fixed</li>
1138 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1139 URIs</li>
1140</ul>
1141
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1142<h3>1.8.6: Jan 31 2000</h3>
1143<ul>
1144 <li>added a nanoFTP transport module, debugged until the new version of <a
1145 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1146 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1147</ul>
1148
1149<h3>1.8.5: Jan 21 2000</h3>
1150<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1151 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1152 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1153 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1154 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1155 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1156 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1157 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1158 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1159</ul>
1160
1161<h3>1.8.4: Jan 13 2000</h3>
1162<ul>
1163 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1164 <li>all exit() call should have been removed from libxml</li>
1165 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1166 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1167</ul>
1168
1169<h3>1.8.3: Jan 5 2000</h3>
1170<ul>
1171 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1172 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1173 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1174 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1175 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1176 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1177 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1178 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1179 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1180</ul>
1181
1182<h3>1.8.2: Dec 21 1999</h3>
1183<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1184 <li>I got another problem with includes and C++, I hope this issue is fixed
1185 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1186 <li>Added a few tree modification functions: xmlReplaceNode,
1187 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1188 xmlDocSetRootElement</li>
1189 <li>Tried to improve the HTML output with help from <a
1190 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1191</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1192
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1193<h3>1.8.1: Dec 18 1999</h3>
1194<ul>
1195 <li>various patches to avoid troubles when using libxml with C++ compilers
1196 the "namespace" keyword and C escaping in include files</li>
1197 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1198 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1199 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1200 <li>fixed a posteriori validation (validation after parsing, or by using a
1201 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1202 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1203</ul>
1204
1205<h3>1.8.0: Dec 12 1999</h3>
1206<ul>
1207 <li>cleanup, especially memory wise</li>
1208 <li>the parser should be more reliable, especially the HTML one, it should
1209 not crash, whatever the input !</li>
1210 <li>Integrated various patches, especially a speedup improvement for large
1211 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1212 configure with --with-buffers to enable them.</li>
1213 <li>attribute normalization, oops should have been added long ago !</li>
1214 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1215 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1216</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1217
1218<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1219<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1220 <li>Lots of HTML improvement</li>
1221 <li>Fixed some errors when saving both XML and HTML</li>
1222 <li>More examples, the regression tests should now look clean</li>
1223 <li>Fixed a bug with contiguous charref</li>
1224</ul>
1225
1226<h3>1.7.3: Sep 29 1999</h3>
1227<ul>
1228 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1229 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1230 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1231</ul>
1232
1233<h3>1.7.1: Sep 24 1999</h3>
1234<ul>
1235 <li>The basic type for strings manipulated by libxml has been renamed in
1236 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1237 is that CHAR was conflicting with a predefined type on Windows. However
1238 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1239 <strong>#define </strong>.</li>
1240 <li>Changed another error : the use of a structure field called errno, and
1241 leading to troubles on platforms where it's a macro</li>
1242</ul>
1243
1244<h3>1.7.0: sep 23 1999</h3>
1245<ul>
1246 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1247 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1248 <li>Added an errno to report errors by another mean than a simple printf
1249 like callback</li>
1250 <li>Finished ID/IDREF support and checking when validation</li>
1251 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1252 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1253 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1254 implementation</li>
1255 <li>Added an HTML parser front-end</li>
1256</ul>
1257
1258<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1259
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1260<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]1261markup-based structured documents. Here is <a name="example">an example XML
1262document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1263<pre>&lt;?xml version="1.0"?&gt;
1264&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1265 &lt;head&gt;
1266 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1267 &lt;/head&gt;
1268 &lt;chapter&gt;
1269 &lt;title&gt;The Linux adventure&lt;/title&gt;
1270 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1271 &lt;image href="linus.gif"/&gt;
1272 &lt;p&gt;...&lt;/p&gt;
1273 &lt;/chapter&gt;
1274&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1275
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1276<p>The first line specifies that it's an XML document and gives useful
1277information about its encoding. Then the document is a text format whose
1278structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1279to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1280(no content), a single tag can serve as both the opening and closing tag if
1281it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1282that, for example, the image tag has no content (just an attribute) and is
1283closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1284
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1285<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]1286structured document maintenance (where it follows the steps of SGML) to
1287simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1288spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1289it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1290
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1291<h2><a name="XSLT">XSLT</a></h2>
1292
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1293<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1294
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1295<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1296language for transforming XML documents into other XML documents (or
1297HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1298
1299<p>A separate library called libxslt is being built on top of libxml2. This
1300module "libxslt" can be found in the Gnome CVS base too.</p>
1301
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1302<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1303href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1304supported and the progresses on the <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1305href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog"
1306name="Changelog">Changelog</a></p>
1307
1308<h2><a name="Python">Python and bindings</a></h2>
1309
1310<p>There is a number of language bindings and wrappers available for libxml2,
1311the list below is not exhaustive. Please contact the <a
1312href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
1313(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
1314order to get updates to this list or to discuss the specific topic of libxml2
1315or libxslt wrappers or bindings:</p>
1316<ul>
1317 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
1318 provides a C++ wrapper for libxml:<br>
1319 Website: <a
1320 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
1321 Download: <a
1322 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
1323 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
1324 based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
1325 <li><a
1326 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
1327 Sergeant</a>
1328 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
1329 wrapper for libxml2/libxslt as part of the <a
1330 href="http://axkit.com/">AxKit XML application server</a></li>
1331 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
1332 provides and earlier version of the libxml/libxslt <a
1333 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
1334 <li>Petr Kozelka provides <a
1335 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
1336 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
1337 <li>Wai-Sun "Squidster" Chia provides <a
1338 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
1339 libxml2 bindings are also available in Ruby through the <a
1340 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
1341 maintained by Tobias Peters.</li>
Daniel Veillardb9e469a2002-02-21 12:08:42 +0000[diff] [blame^]1342 <li>Steve Ball and contributors maintains
1343 <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
1344 Tcl</a>
1345 <li>There is support for libxml2 in the DOM module of PHP.
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1346</ul>
1347
1348<p>The distribution includes a set of Python bindings, which are garanteed to
1349be maintained as part of the library in the future, though the Python
1350interface have not yet reached the maturity of the C API. The distribution
1351includes a set of examples and regression tests for the python bindings in
1352the <code>python/tests</code> directory. Here are some excepts from those
1353tests:</p>
1354
1355<h3>tst.py:</h3>
1356
1357<p>This is a basic test of the file interface and DOM navigation:</p>
1358<pre>import libxml2
1359
1360doc = libxml2.parseFile("tst.xml")
1361if doc.name != "tst.xml":
1362 print "doc.name failed"
1363 sys.exit(1)
1364root = doc.children
1365if root.name != "doc":
1366 print "root.name failed"
1367 sys.exit(1)
1368child = root.children
1369if child.name != "foo":
1370 print "child.name failed"
1371 sys.exit(1)
1372doc.freeDoc()</pre>
1373
1374<p>The Python module is called libxml2, parseFile is the equivalent of
1375xmlParseFile (most of the bindings are automatically generated, and the xml
1376prefix is removed and the casing convention are kept). All node seen at the
1377binding level share the same subset of accesors:</p>
1378<ul>
1379 <li><code>name</code>
1380 : returns the node name</li>
1381 <li><code>type</code>
1382 : returns a string indicating the node typ<code>e</code></li>
1383 <li><code>content</code>
1384 : returns the content of the node, it is based on xmlNodeGetContent() and
1385 hence is recursive.</li>
1386 <li><code>parent</code>
1387 , <code>children</code>, <code>last</code>, <code>next</code>,
1388 <code>prev</code>, <code>doc</code>, <code>properties</code>: pointing to
1389 the associated element in the tree, those may return None in case no such
1390 link exists.</li>
1391</ul>
1392
1393<p>Also note the need to explicitely deallocate documents with freeDoc() .
1394Reference counting for libxml2 trees would need quite a lot of work to
1395function properly, and rather than risk memory leaks if not implemented
1396correctly it sounds safer to have an explicit function to free a tree. The
1397wrapper python objects like doc, root or child are them automatically garbage
1398collected.</p>
1399
1400<h3>validate.py:</h3>
1401
1402<p>This test check the validation interfaces and redirection of error
1403messages:</p>
1404<pre>import libxml2
1405
1406#desactivate error messages from the validation
1407def noerr(ctx, str):
1408 pass
1409
1410libxml2.registerErrorHandler(noerr, None)
1411
1412ctxt = libxml2.createFileParserCtxt("invalid.xml")
1413ctxt.validate(1)
1414ctxt.parseDocument()
1415doc = ctxt.doc()
1416valid = ctxt.isValid()
1417doc.freeDoc()
1418if valid != 0:
1419 print "validity chec failed"</pre>
1420
1421<p>The first thing to notice is the call to registerErrorHandler(), it
1422defines a new error handler global to the library. It is used to avoid seeing
1423the error messages when trying to validate the invalid document.</p>
1424
1425<p>The main interest of that test is the creation of a parser context with
1426createFileParserCtxt() and how the behaviour can be changed before calling
1427parseDocument() . Similary the informations resulting from the parsing phase
1428are also available using context methods.</p>
1429
1430<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
1431C function interfaces in terms of objects method as much as possible. The
1432best to get a complete view of what methods are supported is to look at the
1433libxml2.py module containing all the wrappers.</p>
1434
1435<h3>push.py:</h3>
1436
1437<p>This test show how to activate the push parser interface:</p>
1438<pre>import libxml2
1439
1440ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
1441ctxt.parseChunk("/&gt;", 2, 1)
1442doc = ctxt.doc()
1443
1444doc.freeDoc()</pre>
1445
1446<p>The context is created with a speciall call based on the
1447xmlCreatePushParser() from the C library. The first argument is an optional
1448SAX callback object, then the initial set of data, the lenght and the name of
1449the resource in case URI-References need to be computed by the parser.</p>
1450
1451<p>Then the data are pushed using the parseChunk() method, the last call
1452setting the thrird argument terminate to 1.</p>
1453
1454<h3>pushSAX.py:</h3>
1455
1456<p>this test show the use of the event based parsing interfaces. In this case
1457the parser does not build a document, but provides callback information as
1458the parser makes progresses analyzing the data being provided:</p>
1459<pre>import libxml2
1460log = ""
1461
1462class callback:
1463 def startDocument(self):
1464 global log
1465 log = log + "startDocument:"
1466
1467 def endDocument(self):
1468 global log
1469 log = log + "endDocument:"
1470
1471 def startElement(self, tag, attrs):
1472 global log
1473 log = log + "startElement %s %s:" % (tag, attrs)
1474
1475 def endElement(self, tag):
1476 global log
1477 log = log + "endElement %s:" % (tag)
1478
1479 def characters(self, data):
1480 global log
1481 log = log + "characters: %s:" % (data)
1482
1483 def warning(self, msg):
1484 global log
1485 log = log + "warning: %s:" % (msg)
1486
1487 def error(self, msg):
1488 global log
1489 log = log + "error: %s:" % (msg)
1490
1491 def fatalError(self, msg):
1492 global log
1493 log = log + "fatalError: %s:" % (msg)
1494
1495handler = callback()
1496
1497ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
1498chunk = " url='tst'&gt;b"
1499ctxt.parseChunk(chunk, len(chunk), 0)
1500chunk = "ar&lt;/foo&gt;"
1501ctxt.parseChunk(chunk, len(chunk), 1)
1502
1503reference = "startDocument:startElement foo {'url': 'tst'}:characters: bar:endElement foo:endDocument:"
1504if log != reference:
1505 print "Error got: %s" % log
1506 print "Exprected: %s" % reference</pre>
1507
1508<p>The key object in that test is the handler, it provides a number of entry
1509points which can be called by the parser as it makes progresses to indicate
1510the information set obtained. The full set of callback is larger than what
1511the callback class in that specific example implements (see the SAX
1512definition for a complete list). The wrapper will only call those supplied by
1513the object when activated. The startElement receives the names of the element
1514and a dictionnary containing the attributes carried by this element.</p>
1515
1516<p>Also note that the reference string generated from the callback shows a
1517single character call even though the string "bar" is passed to the parser
1518from 2 different call to parseChunk()</p>
1519
1520<h3>xpath.py:</h3>
1521
1522<p>This is a basic test of XPath warppers support</p>
1523<pre>import libxml2
1524
1525doc = libxml2.parseFile("tst.xml")
1526ctxt = doc.xpathNewContext()
1527res = ctxt.xpathEval("//*")
1528if len(res) != 2:
1529 print "xpath query: wrong node set size"
1530 sys.exit(1)
1531if res[0].name != "doc" or res[1].name != "foo":
1532 print "xpath query: wrong node set value"
1533 sys.exit(1)
1534doc.freeDoc()
1535ctxt.xpathFreeContext()</pre>
1536
1537<p>This test parses a file, then create an XPath context to evaluate XPath
1538expression on it. The xpathEval() method execute an XPath query and returns
1539the result mapped in a Python way. String and numbers are natively converted,
1540and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
1541the document, the XPath context need to be freed explicitely, also not that
1542the result of the XPath query may point back to the document tree and hence
1543the document must be freed after the result of the query is used.</p>
1544
1545<h3>xpathext.py:</h3>
1546
1547<p>This test shows how to extend the XPath engine with functions written in
1548python:</p>
1549<pre>import libxml2
1550
1551def foo(ctx, x):
1552 return x + 1
1553
1554doc = libxml2.parseFile("tst.xml")
1555ctxt = doc.xpathNewContext()
1556libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
1557res = ctxt.xpathEval("foo(1)")
1558if res != 2:
1559 print "xpath extension failure"
1560doc.freeDoc()
1561ctxt.xpathFreeContext()</pre>
1562
1563<p>Note how the extension function is registered with the context (but that
1564part is not yet finalized, ths may change slightly in the future).</p>
1565
1566<h3>tstxpath.py:</h3>
1567
1568<p>This test is similar to the previousone but shows how the extension
1569function can access the XPath evaluation context:</p>
1570<pre>def foo(ctx, x):
1571 global called
1572
1573 #
1574 # test that access to the XPath evaluation contexts
1575 #
1576 pctxt = libxml2.xpathParserContext(_obj=ctx)
1577 ctxt = pctxt.context()
1578 called = ctxt.function()
1579 return x + 1</pre>
1580
1581<p>All the interfaces around the XPath parser(or rather evaluation) context
1582are not finalized, but it should be sufficient to do contextual work at the
1583evaluation point.</p>
1584
1585<h3>Memory debugging:</h3>
1586
1587<p>last but not least, all tests starts with the following prologue:</p>
1588<pre>#memory debug specific
1589libxml2.debugMemory(1)
1590</pre>
1591
1592<p>and ends with the following epilogue:</p>
1593<pre>#memory debug specific
1594libxml2.cleanupParser()
1595if libxml2.debugMemory(1) == 0:
1596 print "OK"
1597else:
1598 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
1599 libxml2.dumpMemory()</pre>
1600
1601<p>Those activate the memory debugging interface of libxml2 where all
1602alloacted block in the library are tracked. The prologue then cleans up the
1603library state and checks that all allocated memory has been freed. If not it
1604calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1605
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1606<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1607
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1608<p>Libxml is made of multiple components; some of them are optional, and most
1609of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1610<ul>
1611 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1612 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1613 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1614 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1615 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1616 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1617 <li>a SAX tree module to build an in-memory DOM representation</li>
1618 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1619 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1620 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1621 (optional)</li>
1622 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1623</ul>
1624
1625<p>Graphically this gives the following:</p>
1626
1627<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1628
1629<p></p>
1630
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1631<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1632
1633<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1634returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1635<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1636as the file name, the document type, and a <strong>children</strong> pointer
1637which is the root of the document (or more exactly the first child under the
1638root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1639chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1640relationship. An xmlNode can also carry properties (a chain of xmlAttr
1641structures). An attribute may have a value which is a list of TEXT or
1642ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1643
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1644<p>Here is an example (erroneous with respect to the XML spec since there
1645should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1646
1647<p><img src="structure.gif" alt=" structure.gif "></p>
1648
1649<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1650called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1651prints them back as parsed. This is useful for detecting errors both in XML
1652code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1653which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1654result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1655<pre>DOCUMENT
1656version=1.0
1657standalone=true
1658 ELEMENT EXAMPLE
1659 ATTRIBUTE prop1
1660 TEXT
1661 content=gnome is great
1662 ATTRIBUTE prop2
1663 ENTITY_REF
1664 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1665 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1666 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1667 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1668 TEXT
1669 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1670 ELEMENT chapter
1671 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1672 TEXT
1673 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1674 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1675 TEXT
1676 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1677 ELEMENT image
1678 ATTRIBUTE href
1679 TEXT
1680 content=linus.gif
1681 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1682 TEXT
1683 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1684
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1685<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1686
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1687<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1688
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1689<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1690memory. 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]1691loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1692a <strong>callback-based interface</strong> to the parser. Before parsing,
1693the application layer registers a customized set of callbacks which are
1694called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1695
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1696<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]1697libxml, see the <a
1698href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1699documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1700Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1701
1702<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1703program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1704binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1705distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1706testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1707<pre>SAX.setDocumentLocator()
1708SAX.startDocument()
1709SAX.getEntity(amp)
1710SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1711SAX.characters( , 3)
1712SAX.startElement(head)
1713SAX.characters( , 4)
1714SAX.startElement(title)
1715SAX.characters(Welcome to Gnome, 16)
1716SAX.endElement(title)
1717SAX.characters( , 3)
1718SAX.endElement(head)
1719SAX.characters( , 3)
1720SAX.startElement(chapter)
1721SAX.characters( , 4)
1722SAX.startElement(title)
1723SAX.characters(The Linux adventure, 19)
1724SAX.endElement(title)
1725SAX.characters( , 4)
1726SAX.startElement(p)
1727SAX.characters(bla bla bla ..., 15)
1728SAX.endElement(p)
1729SAX.characters( , 4)
1730SAX.startElement(image, href='linus.gif')
1731SAX.endElement(image)
1732SAX.characters( , 4)
1733SAX.startElement(p)
1734SAX.characters(..., 3)
1735SAX.endElement(p)
1736SAX.characters( , 3)
1737SAX.endElement(chapter)
1738SAX.characters( , 1)
1739SAX.endElement(EXAMPLE)
1740SAX.endDocument()</pre>
1741
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1742<p>Most of the other interfaces of libxml are based on the DOM tree-building
1743facility, so nearly everything up to the end of this document presupposes the
1744use of the standard DOM tree build. Note that the DOM tree itself is built by
1745a set of registered default callbacks, without internal specific
1746interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1747
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1748<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1749
1750<p>Table of Content:</p>
1751<ol>
1752 <li><a href="#General5">General overview</a></li>
1753 <li><a href="#definition">The definition</a></li>
1754 <li><a href="#Simple">Simple rules</a>
1755 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1756 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1757 <li><a href="#Declaring">Declaring elements</a></li>
1758 <li><a href="#Declaring1">Declaring attributes</a></li>
1759 </ol>
1760 </li>
1761 <li><a href="#Some">Some examples</a></li>
1762 <li><a href="#validate">How to validate</a></li>
1763 <li><a href="#Other">Other resources</a></li>
1764</ol>
1765
1766<h3><a name="General5">General overview</a></h3>
1767
1768<p>Well what is validation and what is a DTD ?</p>
1769
1770<p>DTD is the acronym for Document Type Definition. This is a description of
1771the content for a familly of XML files. This is part of the XML 1.0
1772specification, and alows to describe and check that a given document instance
1773conforms to a set of rules detailing its structure and content.</p>
1774
1775<p>Validation is the process of checking a document against a DTD (more
1776generally against a set of construction rules).</p>
1777
1778<p>The validation process and building DTDs are the two most difficult parts
1779of the XML life cycle. Briefly a DTD defines all the possibles element to be
1780found within your document, what is the formal shape of your document tree
1781(by defining the allowed content of an element, either text, a regular
1782expression for the allowed list of children, or mixed content i.e. both text
1783and children). The DTD also defines the allowed attributes for all elements
1784and the types of the attributes.</p>
1785
1786<h3><a name="definition1">The definition</a></h3>
1787
1788<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1789href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1790Rev1</a>):</p>
1791<ul>
1792 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1793 elements</a></li>
1794 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1795 attributes</a></li>
1796</ul>
1797
1798<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1799ancient...</p>
1800
1801<h3><a name="Simple1">Simple rules</a></h3>
1802
1803<p>Writing DTD can be done in multiple ways, the rules to build them if you
1804need something fixed or something which can evolve over time can be radically
1805different. Really complex DTD like Docbook ones are flexible but quite harder
1806to design. I will just focuse on DTDs for a formats with a fixed simple
1807structure. It is just a set of basic rules, and definitely not exhaustive nor
1808useable for complex DTD design.</p>
1809
1810<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1811
1812<p>Assuming the top element of the document is <code>spec</code> and the dtd
1813is placed in the file <code>mydtd</code> in the subdirectory
1814<code>dtds</code> of the directory from where the document were loaded:</p>
1815
1816<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1817
1818<p>Notes:</p>
1819<ul>
1820 <li>the system string is actually an URI-Reference (as defined in <a
1821 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1822 full URL string indicating the location of your DTD on the Web, this is a
1823 really good thing to do if you want others to validate your document</li>
1824 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1825 magic string) so that the DTd is looked up in catalogs on the client side
1826 without having to locate it on the web</li>
1827 <li>a dtd contains a set of elements and attributes declarations, but they
1828 don't define what the root of the document should be. This is explicitely
1829 told to the parser/validator as the first element of the
1830 <code>DOCTYPE</code> declaration.</li>
1831</ul>
1832
1833<h4><a name="Declaring2">Declaring elements</a>:</h4>
1834
1835<p>The following declares an element <code>spec</code>:</p>
1836
1837<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1838
1839<p>it also expresses that the spec element contains one <code>front</code>,
1840one <code>body</code> and one optionnal <code>back</code> children elements
1841in this order. The declaration of one element of the structure and its
1842content are done in a single declaration. Similary the following declares
1843<code>div1</code> elements:</p>
1844
Daniel Veillard51737272002-01-23 23:10:38 +0000[diff] [blame]1845<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2?)&gt;</code></p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1846
1847<p>means div1 contains one <code>head</code> then a series of optional
1848<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1849optional <code>div2</code>. And last but not least an element can contain
1850text:</p>
1851
1852<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1853
1854<p><code>b</code> contains text or being of mixed content (text and elements
1855in no particular order):</p>
1856
1857<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1858
1859<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1860<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1861order.</p>
1862
1863<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1864
1865<p>again the attributes declaration includes their content definition:</p>
1866
1867<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1868
1869<p>means that the element <code>termdef</code> can have a <code>name</code>
1870attribute containing text (<code>CDATA</code>) and which is optionnal
1871(<code>#IMPLIED</code>). The attribute value can also be defined within a
1872set:</p>
1873
1874<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1875"ordered"&gt;</code></p>
1876
1877<p>means <code>list</code> element have a <code>type</code> attribute with 3
1878allowed values "bullets", "ordered" or "glossary" and which default to
1879"ordered" if the attribute is not explicitely specified.</p>
1880
1881<p>The content type of an attribute can be text (<code>CDATA</code>),
1882anchor/reference/references
1883(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1884(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1885(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1886<code>chapter</code> element can have an optional <code>id</code> attribute
1887of type <code>ID</code>, usable for reference from attribute of type
1888IDREF:</p>
1889
1890<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1891
1892<p>The last value of an attribute definition can be <code>#REQUIRED
1893</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1894meaning that it is optional, or the default value (possibly prefixed by
1895<code>#FIXED</code> if it is the only allowed).</p>
1896
1897<p>Notes:</p>
1898<ul>
1899 <li>usually the attributes pertaining to a given element are declared in a
1900 single expression, but it is just a convention adopted by a lot of DTD
1901 writers:
1902 <pre>&lt;!ATTLIST termdef
1903 id ID #REQUIRED
1904 name CDATA #IMPLIED&gt;</pre>
1905 <p>The previous construct defines both <code>id</code> and
1906 <code>name</code> attributes for the element <code>termdef</code></p>
1907 </li>
1908</ul>
1909
1910<h3><a name="Some1">Some examples</a></h3>
1911
1912<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1913contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1914example shows an XML file where the simple DTD is directly included within
1915the document.</p>
1916
1917<h3><a name="validate1">How to validate</a></h3>
1918
1919<p>The simplest is to use the xmllint program comming with libxml. The
1920<code>--valid</code> option turn on validation of the files given as input,
1921for example the following validates a copy of the first revision of the XML
19221.0 specification:</p>
1923
1924<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1925
1926<p>the -- noout is used to not output the resulting tree.</p>
1927
1928<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1929a given DTD.</p>
1930
1931<p>Libxml exports an API to handle DTDs and validation, check the <a
1932href="http://xmlsoft.org/html/libxml-valid.html">associated
1933description</a>.</p>
1934
1935<h3><a name="Other1">Other resources</a></h3>
1936
1937<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1938will just list one for now, others pointers welcome:</p>
1939<ul>
1940 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1941</ul>
1942
1943<p>I suggest looking at the examples found under test/valid/dtd and any of
1944the large number of books available on XML. The dia example in test/valid
1945should be both simple and complete enough to allow you to build your own.</p>
1946
1947<p></p>
1948
1949<h2><a name="Memory">Memory Management</a></h2>
1950
1951<p>Table of Content:</p>
1952<ol>
1953 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1954 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1955 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1956 <li><a href="#Debugging">Debugging routines</a></li>
1957 <li><a href="#General4">General memory requirements</a></li>
1958</ol>
1959
1960<h3><a name="General3">General overview</a></h3>
1961
1962<p>The module <code><a
1963href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1964provides the interfaces to the libxml memory system:</p>
1965<ul>
1966 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1967 xmlMalloc() and xmlRealloc()</li>
1968 <li>those routines can be reallocated to a specific set of routine, by
1969 default the libc ones i.e. free(), malloc() and realloc()</li>
1970 <li>the xmlmemory.c module includes a set of debugging routine</li>
1971</ul>
1972
1973<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1974
1975<p>It is sometimes useful to not use the default memory allocator, either for
1976debugging, analysis or to implement a specific behaviour on memory management
1977(like on embedded systems). Two function calls are available to do so:</p>
1978<ul>
1979 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1980 which return the current set of functions in use by the parser</li>
1981 <li><a
1982 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1983 which allow to set up a new set of memory allocation functions</li>
1984</ul>
1985
1986<p>Of course a call to xmlMemSetup() should probably be done before calling
1987any other libxml routines (unless you are sure your allocations routines are
1988compatibles).</p>
1989
1990<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1991
1992<p>Libxml is not stateless, there is a few set of memory structures needing
1993allocation before the parser is fully functionnal (some encoding structures
1994for example). This also mean that once parsing is finished there is a tiny
1995amount of memory (a few hundred bytes) which can be recollected if you don't
1996reuse the parser immediately:</p>
1997<ul>
1998 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1999 ()</a>
2000 is a centralized routine to free the parsing states. Note that it won't
2001 deallocate any produced tree if any (use the xmlFreeDoc() and related
2002 routines for this).</li>
2003 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
2004 ()</a>
2005 is the dual routine allowing to preallocate the parsing state which can
2006 be useful for example to avoid initialization reentrancy problems when
2007 using libxml in multithreaded applications</li>
2008</ul>
2009
2010<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
2011at the next invocation of parser routines, but be careful of the consequences
2012in multithreaded applications.</p>
2013
2014<h3><a name="Debugging">Debugging routines</a></h3>
2015
2016<p>When configured using --with-mem-debug flag (off by default), libxml uses
2017a set of memory allocation debugging routineskeeping track of all allocated
2018blocks and the location in the code where the routine was called. A couple of
2019other debugging routines allow to dump the memory allocated infos to a file
2020or call a specific routine when a given block number is allocated:</p>
2021<ul>
2022 <li><a
2023 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
2024 <a
2025 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
2026 and <a
2027 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
2028 are the memory debugging replacement allocation routines</li>
2029 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
2030 ()</a>
2031 dumps all the informations about the allocated memory block lefts in the
2032 <code>.memdump</code> file</li>
2033</ul>
2034
2035<p>When developping libxml memory debug is enabled, the tests programs call
2036xmlMemoryDump () and the "make test" regression tests will check for any
2037memory leak during the full regression test sequence, this helps a lot
2038ensuring that libxml does not leak memory and bullet proof memory
2039allocations use (some libc implementations are known to be far too permissive
2040resulting in major portability problems!).</p>
2041
2042<p>If the .memdump reports a leak, it displays the allocation function and
2043also tries to give some informations about the content and structure of the
2044allocated blocks left. This is sufficient in most cases to find the culprit,
2045but not always. Assuming the allocation problem is reproductible, it is
2046possible to find more easilly:</p>
2047<ol>
2048 <li>write down the block number xxxx not allocated</li>
2049 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
2050 <li>run the program under a debugger and set a breakpoint on
2051 xmlMallocBreakpoint() a specific function called when this precise block
2052 is allocated</li>
2053 <li>when the breakpoint is reached you can then do a fine analysis of the
2054 allocation an step to see the condition resulting in the missing
2055 deallocation.</li>
2056</ol>
2057
2058<p>I used to use a commercial tool to debug libxml memory problems but after
2059noticing that it was not detecting memory leaks that simple mechanism was
2060used and proved extremely efficient until now.</p>
2061
2062<h3><a name="General4">General memory requirements</a></h3>
2063
2064<p>How much libxml memory require ? It's hard to tell in average it depends
2065of a number of things:</p>
2066<ul>
2067 <li>the parser itself should work in a fixed amout of memory, except for
2068 information maintained about the stacks of names and entities locations.
2069 The I/O and encoding handlers will probably account for a few KBytes.
2070 This is true for both the XML and HTML parser (though the HTML parser
2071 need more state).</li>
2072 <li>If you are generating the DOM tree then memory requirements will grow
2073 nearly lineary with the size of the data. In general for a balanced
2074 textual document the internal memory requirement is about 4 times the
2075 size of the UTF8 serialization of this document (exmple the XML-1.0
2076 recommendation is a bit more of 150KBytes and takes 650KBytes of main
2077 memory when parsed). Validation will add a amount of memory required for
2078 maintaining the external Dtd state which should be linear with the
2079 complexity of the content model defined by the Dtd</li>
2080 <li>If you don't care about the advanced features of libxml like
2081 validation, DOM, XPath or XPointer, but really need to work fixed memory
2082 requirements, then the SAX interface should be used.</li>
2083</ul>
2084
2085<p></p>
2086
2087<h2><a name="Encodings">Encodings support</a></h2>
2088
2089<p>Table of Content:</p>
2090<ol>
2091 <li><a href="encoding.html#What">What does internationalization support
2092 mean ?</a></li>
2093 <li><a href="encoding.html#internal">The internal encoding, how and
2094 why</a></li>
2095 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
2096 <li><a href="encoding.html#Default">Default supported encodings</a></li>
2097 <li><a href="encoding.html#extend">How to extend the existing
2098 support</a></li>
2099</ol>
2100
2101<h3><a name="What">What does internationalization support mean ?</a></h3>
2102
2103<p>XML was designed from the start to allow the support of any character set
2104by using Unicode. Any conformant XML parser has to support the UTF-8 and
2105UTF-16 default encodings which can both express the full unicode ranges. UTF8
2106is a variable length encoding whose greatest point are to resuse the same
2107emcoding for ASCII and to save space for Western encodings, but it is a bit
2108more complex to handle in practice. UTF-16 use 2 bytes per characters (and
2109sometimes combines two pairs), it makes implementation easier, but looks a
2110bit overkill for Western languages encoding. Moreover the XML specification
2111allows document to be encoded in other encodings at the condition that they
2112are clearly labelled as such. For example the following is a wellformed XML
2113document encoded in ISO-8859 1 and using accentuated letter that we French
2114likes for both markup and content:</p>
2115<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2116&lt;très&gt;là&lt;/très&gt;</pre>
2117
2118<p>Having internationalization support in libxml means the foolowing:</p>
2119<ul>
2120 <li>the document is properly parsed</li>
2121 <li>informations about it's encoding are saved</li>
2122 <li>it can be modified</li>
2123 <li>it can be saved in its original encoding</li>
2124 <li>it can also be saved in another encoding supported by libxml (for
2125 example straight UTF8 or even an ASCII form)</li>
2126</ul>
2127
2128<p>Another very important point is that the whole libxml API, with the
2129exception of a few routines to read with a specific encoding or save to a
2130specific encoding, is completely agnostic about the original encoding of the
2131document.</p>
2132
2133<p>It should be noted too that the HTML parser embedded in libxml now obbey
2134the same rules too, the following document will be (as of 2.2.2) handled in
2135an internationalized fashion by libxml too:</p>
2136<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
2137 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
2138&lt;html lang="fr"&gt;
2139&lt;head&gt;
2140 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
2141&lt;/head&gt;
2142&lt;body&gt;
2143&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
2144&lt;/html&gt;</pre>
2145
2146<h3><a name="internal">The internal encoding, how and why</a></h3>
2147
2148<p>One of the core decision was to force all documents to be converted to a
2149default internal encoding, and that encoding to be UTF-8, here are the
2150rationale for those choices:</p>
2151<ul>
2152 <li>keeping the native encoding in the internal form would force the libxml
2153 users (or the code associated) to be fully aware of the encoding of the
2154 original document, for examples when adding a text node to a document,
2155 the content would have to be provided in the document encoding, i.e. the
2156 client code would have to check it before hand, make sure it's conformant
2157 to the encoding, etc ... Very hard in practice, though in some specific
2158 cases this may make sense.</li>
2159 <li>the second decision was which encoding. From the XML spec only UTF8 and
2160 UTF16 really makes sense as being the two only encodings for which there
2161 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
2162 considered an intelligent choice too since it's a direct Unicode mapping
2163 support. I selected UTF-8 on the basis of efficiency and compatibility
2164 with surrounding software:
2165 <ul>
2166 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
2167 more costly to import and export CPU wise) is also far more compact
2168 than UTF-16 (and UCS-4) for a majority of the documents I see it used
2169 for right now (RPM RDF catalogs, advogato data, various configuration
2170 file formats, etc.) and the key point for today's computer
2171 architecture is efficient uses of caches. If one nearly double the
2172 memory requirement to store the same amount of data, this will trash
2173 caches (main memory/external caches/internal caches) and my take is
2174 that this harms the system far more than the CPU requirements needed
2175 for the conversion to UTF-8</li>
2176 <li>Most of libxml version 1 users were using it with straight ASCII
2177 most of the time, doing the conversion with an internal encoding
2178 requiring all their code to be rewritten was a serious show-stopper
2179 for using UTF-16 or UCS-4.</li>
2180 <li>UTF-8 is being used as the de-facto internal encoding standard for
2181 related code like the <a href="http://www.pango.org/">pango</a>
2182 upcoming Gnome text widget, and a lot of Unix code (yep another place
2183 where Unix programmer base takes a different approach from Microsoft
2184 - they are using UTF-16)</li>
2185 </ul>
2186 </li>
2187</ul>
2188
2189<p>What does this mean in practice for the libxml user:</p>
2190<ul>
2191 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
2192 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
2193 is simply to append 0 byte, as usual.</li>
2194 <li>One just need to make sure that when using chars outside the ASCII set,
2195 the values has been properly converted to UTF-8</li>
2196</ul>
2197
2198<h3><a name="implemente">How is it implemented ?</a></h3>
2199
2200<p>Let's describe how all this works within libxml, basically the I18N
2201(internationalization) support get triggered only during I/O operation, i.e.
2202when reading a document or saving one. Let's look first at the reading
2203sequence:</p>
2204<ol>
2205 <li>when a document is processed, we usually don't know the encoding, a
2206 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
2207 ASCII range (0-0x7F) maps with ASCII</li>
2208 <li>the xml declaration if available is parsed, including the encoding
2209 declaration. At that point, if the autodetected encoding is different
2210 from the one declared a call to xmlSwitchEncoding() is issued.</li>
2211 <li>If there is no encoding declaration, then the input has to be in either
2212 UTF-8 or UTF-16, if it is not then at some point when processing the
2213 input, the converter/checker of UTF-8 form will raise an encoding error.
2214 You may end-up with a garbled document, or no document at all ! Example:
2215 <pre>~/XML -&gt; ./xmllint err.xml
2216err.xml:1: error: Input is not proper UTF-8, indicate encoding !
2217&lt;très&gt;là&lt;/très&gt;
2218 ^
2219err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
2220&lt;très&gt;là&lt;/très&gt;
2221 ^</pre>
2222 </li>
2223 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
2224 then search the default registered encoding converters for that encoding.
2225 If it's not within the default set and iconv() support has been compiled
2226 it, it will ask iconv for such an encoder. If this fails then the parser
2227 will report an error and stops processing:
2228 <pre>~/XML -&gt; ./xmllint err2.xml
2229err2.xml:1: error: Unsupported encoding UnsupportedEnc
2230&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
2231 ^</pre>
2232 </li>
2233 <li>From that point the encoder process progressingly the input (it is
2234 plugged as a front-end to the I/O module) for that entity. It captures
2235 and convert on-the-fly the document to be parsed to UTF-8. The parser
2236 itself just does UTF-8 checking of this input and process it
2237 transparently. The only difference is that the encoding information has
2238 been added to the parsing context (more precisely to the input
2239 corresponding to this entity).</li>
2240 <li>The result (when using DOM) is an internal form completely in UTF-8
2241 with just an encoding information on the document node.</li>
2242</ol>
2243
2244<p>Ok then what's happen when saving the document (assuming you
2245colllected/built an xmlDoc DOM like structure) ? It depends on the function
2246called, xmlSaveFile() will just try to save in the original encoding, while
2247xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
2248encoding:</p>
2249<ol>
2250 <li>if no encoding is given, libxml will look for an encoding value
2251 associated to the document and if it exists will try to save to that
2252 encoding,
2253 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
2254 </li>
2255 <li>so if an encoding was specified, either at the API level or on the
2256 document, libxml will again canonalize the encoding name, lookup for a
2257 converter in the registered set or through iconv. If not found the
2258 function will return an error code</li>
2259 <li>the converter is placed before the I/O buffer layer, as another kind of
2260 buffer, then libxml will simply push the UTF-8 serialization to through
2261 that buffer, which will then progressively be converted and pushed onto
2262 the I/O layer.</li>
2263 <li>It is possible that the converter code fails on some input, for example
2264 trying to push an UTF-8 encoded chinese character through the UTF-8 to
2265 ISO-8859-1 converter won't work. Since the encoders are progressive they
2266 will just report the error and the number of bytes converted, at that
2267 point libxml will decode the offending character, remove it from the
2268 buffer and replace it with the associated charRef encoding &amp;#123; and
2269 resume the convertion. This guarante that any document will be saved
2270 without losses (except for markup names where this is not legal, this is
2271 a problem in the current version, in pactice avoid using non-ascci
2272 characters for tags or attributes names @@). A special "ascii" encoding
2273 name is used to save documents to a pure ascii form can be used when
2274 portability is really crucial</li>
2275</ol>
2276
2277<p>Here is a few examples based on the same test document:</p>
2278<pre>~/XML -&gt; ./xmllint isolat1
2279&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2280&lt;très&gt;là&lt;/très&gt;
2281~/XML -&gt; ./xmllint --encode UTF-8 isolat1
2282&lt;?xml version="1.0" encoding="UTF-8"?&gt;
2283&lt;très&gt;là  &lt;/très&gt;
2284~/XML -&gt; </pre>
2285
2286<p>The same processing is applied (and reuse most of the code) for HTML I18N
2287processing. Looking up and modifying the content encoding is a bit more
2288difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
2289so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
2290been provided. The parser also attempts to switch encoding on the fly when
2291detecting such a tag on input. Except for that the processing is the same
2292(and again reuses the same code).</p>
2293
2294<h3><a name="Default">Default supported encodings</a></h3>
2295
2296<p>libxml has a set of default converters for the following encodings
2297(located in encoding.c):</p>
2298<ol>
2299 <li>UTF-8 is supported by default (null handlers)</li>
2300 <li>UTF-16, both little and big endian</li>
2301 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
2302 <li>ASCII, useful mostly for saving</li>
2303 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
2304 predefined entities like &amp;copy; for the Copyright sign.</li>
2305</ol>
2306
2307<p>More over when compiled on an Unix platfor with iconv support the full set
2308of encodings supported by iconv can be instantly be used by libxml. On a
2309linux machine with glibc-2.1 the list of supported encodings and aliases fill
23103 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
2311various Japanese ones.</p>
2312
2313<h4>Encoding aliases</h4>
2314
2315<p>From 2.2.3, libxml has support to register encoding names aliases. The
2316goal is to be able to parse document whose encoding is supported but where
2317the name differs (for example from the default set of names accepted by
2318iconv). The following functions allow to register and handle new aliases for
2319existing encodings. Once registered libxml will automatically lookup the
2320aliases when handling a document:</p>
2321<ul>
2322 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
2323 <li>int xmlDelEncodingAlias(const char *alias);</li>
2324 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
2325 <li>void xmlCleanupEncodingAliases(void);</li>
2326</ul>
2327
2328<h3><a name="extend">How to extend the existing support</a></h3>
2329
2330<p>Well adding support for new encoding, or overriding one of the encoders
2331(assuming it is buggy) should not be hard, just write an input and output
2332conversion routines to/from UTF-8, and register them using
2333xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
2334called automatically if the parser(s) encounter such an encoding name
2335(register it uppercase, this will help). The description of the encoders,
2336their arguments and expected return values are described in the encoding.h
2337header.</p>
2338
2339<p>A quick note on the topic of subverting the parser to use a different
2340internal encoding than UTF-8, in some case people will absolutely want to
2341keep the internal encoding different, I think it's still possible (but the
2342encoding must be compliant with ASCII on the same subrange) though I didn't
2343tried it. The key is to override the default conversion routines (by
2344registering null encoders/decoders for your charsets), and bypass the UTF-8
2345checking of the parser by setting the parser context charset
2346(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2347there is no guarantee taht this will work. You may also have some troubles
2348saving back.</p>
2349
2350<p>Basically proper I18N support is important, this requires at least
2351libxml-2.0.0, but a lot of features and corrections are really available only
2352starting 2.2.</p>
2353
2354<h2><a name="IO">I/O Interfaces</a></h2>
2355
2356<p>Table of Content:</p>
2357<ol>
2358 <li><a href="#General1">General overview</a></li>
2359 <li><a href="#basic">The basic buffer type</a></li>
2360 <li><a href="#Input">Input I/O handlers</a></li>
2361 <li><a href="#Output">Output I/O handlers</a></li>
2362 <li><a href="#entities">The entities loader</a></li>
2363 <li><a href="#Example2">Example of customized I/O</a></li>
2364</ol>
2365
2366<h3><a name="General1">General overview</a></h3>
2367
2368<p>The module <code><a
2369href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2370the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2371<ul>
2372 <li>Entities loader, this is a routine which tries to fetch the entities
2373 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2374 don't look at the public identifier since libxml do not maintain a
2375 catalog. You can redefine you own entity loader by using
2376 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2377 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2378 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2379 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2380 input layer to handle fetching the informations to feed the parser. This
2381 provides buffering and is also a placeholder where the encoding
2382 convertors to UTF8 are piggy-backed.</li>
2383 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2384 task but when generating a serialization from a tree.</li>
2385 <li>A mechanism to register sets of I/O callbacks and associate them with
2386 specific naming schemes like the protocol part of the URIs.
2387 <p>This affect the default I/O operations and allows to use specific I/O
2388 handlers for certain names.</p>
2389 </li>
2390</ul>
2391
2392<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2393example in the HTML parser is the following:</p>
2394<ol>
2395 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2396 the parsing context and the URI string.</li>
2397 <li>the URI string is checked against the existing registered handlers
2398 using their match() callback function, if the HTTP module was compiled
2399 in, it is registered and its match() function will succeeds</li>
2400 <li>the open() function of the handler is called and if successful will
2401 return an I/O Input buffer</li>
2402 <li>the parser will the start reading from this buffer and progressively
2403 fetch information from the resource, calling the read() function of the
2404 handler until the resource is exhausted</li>
2405 <li>if an encoding change is detected it will be installed on the input
2406 buffer, providing buffering and efficient use of the conversion
2407 routines</li>
2408 <li>once the parser has finished, the close() function of the handler is
2409 called once and the Input buffer and associed resources are
2410 deallocated.</li>
2411</ol>
2412
2413<p>The user defined callbacks are checked first to allow overriding of the
2414default libxml I/O routines.</p>
2415
2416<h3><a name="basic">The basic buffer type</a></h3>
2417
2418<p>All the buffer manipulation handling is done using the
2419<code>xmlBuffer</code> type define in <code><a
2420href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2421resizable memory buffer. The buffer allocation strategy can be selected to be
2422either best-fit or use an exponential doubling one (CPU vs. memory use
2423tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2424<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2425system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2426of functions allows to manipulate buffers with names starting with the
2427<code>xmlBuffer...</code> prefix.</p>
2428
2429<h3><a name="Input">Input I/O handlers</a></h3>
2430
2431<p>An Input I/O handler is a simple structure
2432<code>xmlParserInputBuffer</code> containing a context associated to the
2433resource (file descriptor, or pointer to a protocol handler), the read() and
2434close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2435encoding handler are also present to support charset conversion when
2436needed.</p>
2437
2438<h3><a name="Output">Output I/O handlers</a></h3>
2439
2440<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2441Input one except the callbacks are write() and close().</p>
2442
2443<h3><a name="entities">The entities loader</a></h3>
2444
2445<p>The entity loader resolves requests for new entities and create inputs for
2446the parser. Creating an input from a filename or an URI string is done
2447through the xmlNewInputFromFile() routine. The default entity loader do not
2448handle the PUBLIC identifier associated with an entity (if any). So it just
2449calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2450XML).</p>
2451
2452<p>If you want to hook up a catalog mechanism then you simply need to
2453override the default entity loader, here is an example:</p>
2454<pre>#include &lt;libxml/xmlIO.h&gt;
2455
2456xmlExternalEntityLoader defaultLoader = NULL;
2457
2458xmlParserInputPtr
2459xmlMyExternalEntityLoader(const char *URL, const char *ID,
2460 xmlParserCtxtPtr ctxt) {
2461 xmlParserInputPtr ret;
2462 const char *fileID = NULL;
2463 /* lookup for the fileID depending on ID */
2464
2465 ret = xmlNewInputFromFile(ctxt, fileID);
2466 if (ret != NULL)
2467 return(ret);
2468 if (defaultLoader != NULL)
2469 ret = defaultLoader(URL, ID, ctxt);
2470 return(ret);
2471}
2472
2473int main(..) {
2474 ...
2475
2476 /*
2477 * Install our own entity loader
2478 */
2479 defaultLoader = xmlGetExternalEntityLoader();
2480 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2481
2482 ...
2483}</pre>
2484
2485<h3><a name="Example2">Example of customized I/O</a></h3>
2486
2487<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2488real use case</a>, xmlDocDump() closes the FILE * passed by the application
2489and this was a problem. The <a
2490href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2491new output handler with the closing call deactivated:</p>
2492<ol>
2493 <li>First define a new I/O ouput allocator where the output don't close the
2494 file:
2495 <pre>xmlOutputBufferPtr
2496xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2497    xmlOutputBufferPtr ret;
2498    
2499    if (xmlOutputCallbackInitialized == 0)
2500        xmlRegisterDefaultOutputCallbacks();
2501
2502    if (file == NULL) return(NULL);
2503    ret = xmlAllocOutputBuffer(encoder);
2504    if (ret != NULL) {
2505        ret-&gt;context = file;
2506        ret-&gt;writecallback = xmlFileWrite;
2507        ret-&gt;closecallback = NULL; /* No close callback */
2508    }
2509    return(ret); <br>
2510
2511
2512
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2513
2514
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2515
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2516
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2517
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]2518
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]2519
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]2520
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]2521
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]2522
Daniel Veillard9ae4b7a2001-12-13 14:24:09 +0000[diff] [blame]2523
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]2524
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]2525
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2526
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2527
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]2528
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]2529
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]2530
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]2531
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]2532
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]2533
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]2534
2535
2536
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2537} </pre>
2538 </li>
2539 <li>And then use it to save the document:
2540 <pre>FILE *f;
2541xmlOutputBufferPtr output;
2542xmlDocPtr doc;
2543int res;
2544
2545f = ...
2546doc = ....
2547
2548output = xmlOutputBufferCreateOwn(f, NULL);
2549res = xmlSaveFileTo(output, doc, NULL);
2550 </pre>
2551 </li>
2552</ol>
2553
2554<h2><a name="Catalog">Catalog support</a></h2>
2555
2556<p>Table of Content:</p>
2557<ol>
2558 <li><a href="General2">General overview</a></li>
2559 <li><a href="#definition">The definition</a></li>
2560 <li><a href="#Simple">Using catalogs</a></li>
2561 <li><a href="#Some">Some examples</a></li>
2562 <li><a href="#reference">How to tune catalog usage</a></li>
2563 <li><a href="#validate">How to debug catalog processing</a></li>
2564 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2565 <li><a href="#implemento">The implementor corner quick review of the
2566 API</a></li>
2567 <li><a href="#Other">Other resources</a></li>
2568</ol>
2569
2570<h3><a name="General2">General overview</a></h3>
2571
2572<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2573(a file or a remote resource) references another entity. The catalog lookup
2574is inserted between the moment the reference is recognized by the software
2575(XML parser, stylesheet processing, or even images referenced for inclusion
2576in a rendering) and the time where loading that resource is actually
2577started.</p>
2578
2579<p>It is basically used for 3 things:</p>
2580<ul>
2581 <li>mapping from "logical" names, the public identifiers and a more
2582 concrete name usable for download (and URI). For example it can associate
2583 the logical name
2584 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2585 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2586 downloaded</p>
2587 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2588 </li>
2589 <li>remapping from a given URL to another one, like an HTTP indirection
2590 saying that
2591 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2592 <p>should really be looked at</p>
2593 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2594 </li>
2595 <li>providing a local cache mechanism allowing to load the entities
2596 associated to public identifiers or remote resources, this is a really
2597 important feature for any significant deployment of XML or SGML since it
2598 allows to avoid the aleas and delays associated to fetching remote
2599 resources.</li>
2600</ul>
2601
2602<h3><a name="definition">The definitions</a></h3>
2603
2604<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2605<ul>
2606 <li>the older SGML catalogs, the official spec is SGML Open Technical
2607 Resolution TR9401:1997, but is better understood by reading <a
2608 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2609 James Clark. This is relatively old and not the preferred mode of
2610 operation of libxml.</li>
2611 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2612 Catalogs</a>
2613 is far more flexible, more recent, uses an XML syntax and should scale
2614 quite better. This is the default option of libxml.</li>
2615</ul>
2616
2617<p></p>
2618
2619<h3><a name="Simple">Using catalog</a></h3>
2620
2621<p>In a normal environment libxml will by default check the presence of a
2622catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2623the processing is completely transparent to the document user. To take a
2624concrete example, suppose you are authoring a DocBook document, this one
2625starts with the following DOCTYPE definition:</p>
2626<pre>&lt;?xml version='1.0'?&gt;
2627&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2628 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2629
2630<p>When validating the document with libxml, the catalog will be
2631automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2632DocBk XML V3.1.4//EN" and the system identifier
2633"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2634been installed on your system and the catalogs actually point to them, libxml
2635will fetch them from the local disk.</p>
2636
2637<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2638DOCTYPE example it's a really old version, but is fine as an example.</p>
2639
2640<p>Libxml will check the catalog each time that it is requested to load an
2641entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2642your system is correctly configured all the authoring phase and processing
2643should use only local files, even if your document stays portable because it
2644uses the canonical public and system ID, referencing the remote document.</p>
2645
2646<h3><a name="Some">Some examples:</a></h3>
2647
2648<p>Here is a couple of fragments from XML Catalogs used in libxml early
2649regression tests in <code>test/catalogs</code> :</p>
2650<pre>&lt;?xml version="1.0"?&gt;
2651&lt;!DOCTYPE catalog PUBLIC
2652 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2653 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2654&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2655 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2656 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2657...</pre>
2658
2659<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2660written in XML, there is a specific namespace for catalog elements
2661"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2662catalog is a <code>public</code> mapping it allows to associate a Public
2663Identifier with an URI.</p>
2664<pre>...
2665 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2666 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2667...</pre>
2668
2669<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2670any URI starting with a given prefix should be looked at another URI
2671constructed by replacing the prefix with an new one. In effect this acts like
2672a cache system for a full area of the Web. In practice it is extremely useful
2673with a file prefix if you have installed a copy of those resources on your
2674local system.</p>
2675<pre>...
2676&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2677 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2678&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2679 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2680&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2681 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2682&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2683 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2684&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2685 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2686...</pre>
2687
2688<p>Delegation is the core features which allows to build a tree of catalogs,
2689easier to maintain than a single catalog, based on Public Identifier, System
2690Identifier or URI prefixes it instructs the catalog software to look up
2691entries in another resource. This feature allow to build hierarchies of
2692catalogs, the set of entries presented should be sufficient to redirect the
2693resolution of all DocBook references to the specific catalog in
2694<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2695references for DocBook 4.2.1 to a specific catalog installed at the same time
2696as the DocBook resources on the local machine.</p>
2697
2698<h3><a name="reference">How to tune catalog usage:</a></h3>
2699
2700<p>The user can change the default catalog behaviour by redirecting queries
2701to its own set of catalogs, this can be done by setting the
2702<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2703empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2704default catalog</p>
2705
2706<h3><a name="validate">How to debug catalog processing:</a></h3>
2707
2708<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2709make libxml output debugging informations for each catalog operations, for
2710example:</p>
2711<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2712warning: failed to load external entity "title.xml"
2713orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2714orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2715Failed to parse catalog /etc/xml/catalog
2716Failed to parse catalog /etc/xml/catalog
2717warning: failed to load external entity "title.xml"
2718Catalogs cleanup
2719orchis:~/XML -&gt; </pre>
2720
2721<p>The test/ent2 references an entity, running the parser from memory makes
2722the base URI unavailable and the the "title.xml" entity cannot be loaded.
2723Setting up the debug environment variable allows to detect that an attempt is
2724made to load the <code>/etc/xml/catalog</code> but since it's not present the
2725resolution fails.</p>
2726
2727<p>But the most advanced way to debug XML catalog processing is to use the
2728<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2729catalogs and make resolution queries to see what is going on. This is also
2730used for the regression tests:</p>
2731<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2732 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2733http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2734orchis:~/XML -&gt; </pre>
2735
2736<p>For debugging what is going on, adding one -v flags increase the verbosity
2737level to indicate the processing done (adding a second flag also indicate
2738what elements are recognized at parsing):</p>
2739<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2740 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2741Parsing catalog test/catalogs/docbook.xml's content
2742Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2743http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2744Catalogs cleanup
2745orchis:~/XML -&gt; </pre>
2746
2747<p>A shell interface is also available to debug and process multiple queries
2748(and for regression tests):</p>
2749<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2750 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2751&gt; help
2752Commands available:
2753public PublicID: make a PUBLIC identifier lookup
2754system SystemID: make a SYSTEM identifier lookup
2755resolve PublicID SystemID: do a full resolver lookup
2756add 'type' 'orig' 'replace' : add an entry
2757del 'values' : remove values
2758dump: print the current catalog state
2759debug: increase the verbosity level
2760quiet: decrease the verbosity level
2761exit: quit the shell
2762&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2763http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2764&gt; quit
2765orchis:~/XML -&gt; </pre>
2766
2767<p>This should be sufficient for most debugging purpose, this was actually
2768used heavily to debug the XML Catalog implementation itself.</p>
2769
2770<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2771
2772<p>Basically XML Catalogs are XML files, you can either use XML tools to
2773manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2774to create a catalog the -create option provide this facility:</p>
2775<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2776&lt;?xml version="1.0"?&gt;
2777&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2778 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2779&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2780orchis:~/XML -&gt; </pre>
2781
2782<p>By default xmlcatalog does not overwrite the original catalog and save the
2783result on the standard output, this can be overridden using the -noout
2784option. The <code>-add</code> command allows to add entries in the
2785catalog:</p>
2786<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2787 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2788 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2789orchis:~/XML -&gt; cat tst.xml
2790&lt;?xml version="1.0"?&gt;
2791&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2792 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2793&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2794&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2795 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2796&lt;/catalog&gt;
2797orchis:~/XML -&gt; </pre>
2798
2799<p>The <code>-add</code> option will always take 3 parameters even if some of
2800the XML Catalog constructs (like nextCatalog) will have only a single
2801argument, just pass a third empty string, it will be ignored.</p>
2802
2803<p>Similarly the <code>-del</code> option remove matching entries from the
2804catalog:</p>
2805<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2806 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" 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;
2811orchis:~/XML -&gt; </pre>
2812
2813<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2814exact and would have worked in a similar fashion with the Public ID
2815string.</p>
2816
2817<p>This is rudimentary but should be sufficient to manage a not too complex
2818catalog tree of resources.</p>
2819
2820<h3><a name="implemento">The implementor corner quick review of the
2821API:</a></h3>
2822
2823<p>First, and like for every other module of libxml, there is an
2824automatically generated <a href="html/libxml-catalog.html">API page for
2825catalog support</a>.</p>
2826
2827<p>The header for the catalog interfaces should be included as:</p>
2828<pre>#include &lt;libxml/catalog.h&gt;</pre>
2829
2830<p>The API is voluntarily kept very simple. First it is not obvious that
2831applications really need access to it since it is the default behaviour of
2832libxml (Note: it is possible to completely override libxml default catalog by
2833using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2834plug an application specific resolver).</p>
2835
2836<p>Basically libxml support 2 catalog lists:</p>
2837<ul>
2838 <li>the default one, global shared by all the application</li>
2839 <li>a per-document catalog, this one is built if the document uses the
2840 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2841 associated to the parser context and destroyed when the parsing context
2842 is destroyed.</li>
2843</ul>
2844
2845<p>the document one will be used first if it exists.</p>
2846
2847<h4>Initialization routines:</h4>
2848
2849<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2850used at startup to initialize the catalog, if the catalog should be
2851initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2852should be called before xmlInitializeCatalog() which would otherwise do a
2853default initialization first.</p>
2854
2855<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2856own catalog list if needed.</p>
2857
2858<h4>Preferences setup:</h4>
2859
2860<p>The XML Catalog spec requires the possibility to select default
2861preferences between public and system delegation,
2862xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2863xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2864be forbidden, allowed for global catalog, for document catalog or both, the
2865default is to allow both.</p>
2866
2867<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2868(through the xmlGenericError() mechanism).</p>
2869
2870<h4>Querying routines:</h4>
2871
2872<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2873and xmlCatalogResolveURI() are relatively explicit if you read the XML
2874Catalog specification they correspond to section 7 algorithms, they should
2875also work if you have loaded an SGML catalog with a simplified semantic.</p>
2876
2877<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2878operate on the document catalog list</p>
2879
2880<h4>Cleanup and Miscellaneous:</h4>
2881
2882<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2883the per-document equivalent.</p>
2884
2885<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2886first catalog in the global list, and xmlCatalogDump() allows to dump a
2887catalog state, those routines are primarily designed for xmlcatalog, I'm not
2888sure that exposing more complex interfaces (like navigation ones) would be
2889really useful.</p>
2890
2891<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2892it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2893provided because this functionality may be useful for client tools.</p>
2894
2895<h4>threaded environments:</h4>
2896
2897<p>Since the catalog tree is built progressively, some care has been taken to
2898try to avoid troubles in multithreaded environments. The code is now thread
2899safe assuming that the libxml library has been compiled with threads
2900support.</p>
2901
2902<p></p>
2903
2904<h3><a name="Other">Other resources</a></h3>
2905
2906<p>The XML Catalog specification is relatively recent so there isn't much
2907literature to point at:</p>
2908<ul>
2909 <li>You can find an good rant from Norm Walsh about <a
2910 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2911 need for catalogs</a>, it provides a lot of context informations even if
2912 I don't agree with everything presented.</li>
2913 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2914 catalog proposal</a> from John Cowan</li>
2915 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2916 Language</a> (RDDL) another catalog system but more oriented toward
2917 providing metadata for XML namespaces.</li>
2918 <li>the page from the OASIS Technical <a
2919 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2920 Resolution</a> who maintains XML Catalog, you will find pointers to the
2921 specification update, some background and pointers to others tools
2922 providing XML Catalog support</li>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2923 <li>Here is a <a href="buildDocBookCatalog">shell script</a> to generate
2924 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/
2925 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on
2926 the resources found on the system. Otherwise it will just create
2927 ~/xmlcatalog and ~/dbkxmlcatalog and doing:
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2928 <p><code>export XMLCATALOG=$HOME/xmlcatalog</code></p>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2929 <p>should allow to process DocBook documentations without requiring
2930 network accesses for the DTd or stylesheets</p>
2931 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2932 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2933 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems
2934 to work fine for me too</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2935 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2936 manual page</a></li>
2937</ul>
2938
2939<p>If you have suggestions for corrections or additions, simply contact
2940me:</p>
2941
2942<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2943
2944<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2945using the XML library from the C language. It is not intended to be
2946extensive. I hope the automatically generated documents will provide the
2947completeness required, but as a separate set of documents. The interfaces of
2948the XML library are by principle low level, there is nearly zero abstraction.
2949Those interested in a higher level API should <a href="#DOM">look at
2950DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2951
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2952<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2953separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2954interfaces</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]2955
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2956<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2957
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2958<p>Usually, the first thing to do is to read an XML input. The parser accepts
2959documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2960defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2961<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2962 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2963 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2964 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2965</dl>
2966<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2967 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2968 <dd><p>Parse an XML document contained in a (possibly compressed)
2969 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2970 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2971</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2972
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2973<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]2974failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2975
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2976<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2977
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2978<p>In order for the application to keep the control when the document is
2979being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2980interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2981<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2982 void *user_data,
2983 const char *chunk,
2984 int size,
2985 const char *filename);
2986int xmlParseChunk (xmlParserCtxtPtr ctxt,
2987 const char *chunk,
2988 int size,
2989 int terminate);</pre>
2990
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2991<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2992<pre> FILE *f;
2993
2994 f = fopen(filename, "r");
2995 if (f != NULL) {
2996 int res, size = 1024;
2997 char chars[1024];
2998 xmlParserCtxtPtr ctxt;
2999
3000 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3001 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3002 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
3003 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3004 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3005 xmlParseChunk(ctxt, chars, res, 0);
3006 }
3007 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3008 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3009 xmlFreeParserCtxt(ctxt);
3010 }
3011 }</pre>
3012
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3013<p>The HTML parser embedded into libxml also has a push interface; the
3014functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3015
3016<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
3017
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3018<p>The tree-building interface makes the parser memory-hungry, first loading
3019the document in memory and then building the tree itself. Reading a document
3020without building the tree is possible using the SAX interfaces (see SAX.h and
3021<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]3022Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3023limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3024<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3025
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3026<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3027
3028<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]3029there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3030also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
3031code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3032<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3033 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3034 xmlNodePtr tree, subtree;
3035
3036 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3037 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
3038 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
3039 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
3040 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3041 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3042 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3043 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
3044 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
3045 subtree = xmlNewChild(tree, NULL, "image", NULL);
3046 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3047
3048<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3049
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3050<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3051
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3052<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3053code has access to the internal structure of all the elements of the tree.
3054The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]3055<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3056<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3057example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3058<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3059
3060<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3061<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3062
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3063<p>points to the text node containing the chapter title "The Linux
3064adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3065
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3066<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]3067present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3068to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]3069<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3070
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3071<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3072
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3073<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3074is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3075<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3076 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
3077 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3078 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
3079 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3080 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3081</dl>
3082<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3083 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3084 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]3085 <dd><p>This function returns a pointer to new copy of the property
3086 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3087 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3088</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3089
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3090<p>Two functions are provided for reading and writing the text associated
3091with elements:</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>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3094 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3095 <dd><p>This function takes an "external" string and converts it to one
3096 text node or possibly to a list of entity and text nodes. All
3097 non-predefined entity references like &amp;Gnome; will be stored
3098 internally as entity nodes, hence the result of the function may not be
3099 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3100 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3101</dl>
3102<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3103 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3104 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3105 <dd><p>This function is the inverse of
3106 <code>xmlStringGetNodeList()</code>. It generates a new string
3107 containing the content of the text and entity nodes. Note the extra
3108 argument inLine. If this argument is set to 1, the function will expand
3109 entity references. For example, instead of returning the &amp;Gnome;
3110 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3111 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3112 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3113</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3114
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3115<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3116
3117<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3118<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3119 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3120 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3121 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3122 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3123</dl>
3124<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3125 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3126 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3127 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3128</dl>
3129<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3130 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3131 <dd><p>Saves the document to a file. In this case, the compression
3132 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3133 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3134</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3135
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3136<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3137
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3138<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3139accesses. The level of compression on saves can be turned on either globally
3140or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3141<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3142 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3143 <dd><p>Gets the document compression ratio (0-9).</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>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3148 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3149 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3150</dl>
3151<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3152 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3153 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3154 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3155</dl>
3156<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3157 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3158 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3159 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3160</dl>
3161
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3162<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3163
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3164<p>Entities in principle are similar to simple C macros. An entity defines an
3165abbreviation for a given string that you can reuse many times throughout the
3166content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3167may occur frequently within a document, or to confine the change needed to a
3168document to a restricted area in the internal subset of the document (at the
3169beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3170<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31712 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31723 &lt;!ENTITY xml "Extensible Markup Language"&gt;
31734 ]&gt;
31745 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31756 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31767 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3177
3178<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]3179its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3180are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3181predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3182<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3183for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3184<strong>&amp;quot;</strong> for the character '"', and
3185<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3186
3187<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]3188substitute an entity's content so that you can see the replacement text in
3189your application. Or you may prefer to keep entity references as such in the
3190content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3191precious information (if the user went through the pain of explicitly
3192defining entities, he may have a a rather negative attitude if you blindly
3193susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3194href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3195function allows you to check and change the behaviour, which is to not
3196substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3197
3198<p>Here is the DOM tree built by libxml for the previous document in the
3199default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3200<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3201DOCUMENT
3202version=1.0
3203 ELEMENT EXAMPLE
3204 TEXT
3205 content=
3206 ENTITY_REF
3207 INTERNAL_GENERAL_ENTITY xml
3208 content=Extensible Markup Language
3209 TEXT
3210 content=</pre>
3211
3212<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3213<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3214DOCUMENT
3215version=1.0
3216 ELEMENT EXAMPLE
3217 TEXT
3218 content= Extensible Markup Language</pre>
3219
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3220<p>So, entities or no entities? Basically, it depends on your use case. I
3221suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3222entities in your XML document or data if you are not willing to handle the
3223entity references elements in the DOM tree.</p>
3224
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3225<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3226entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3227transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3228reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3229finding them in the input).</p>
3230
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3231<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3232on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3233non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3234then 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]3235strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]3236deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3237
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3238<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3239
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3240<p>The libxml library implements <a
3241href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
3242recognizing namespace contructs in the input, and does namespace lookup
3243automatically when building the DOM tree. A namespace declaration is
3244associated with an in-memory structure and all elements or attributes within
3245that namespace point to it. Hence testing the namespace is a simple and fast
3246equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3247
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3248<p>I suggest that people using libxml use a namespace, and declare it in the
3249root element of their document as the default namespace. Then they don't need
3250to 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]3251refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3252the size of the XML output significantly, but significantly increases its
3253value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3254<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
3255 &lt;elem1&gt;...&lt;/elem1&gt;
3256 &lt;elem2&gt;...&lt;/elem2&gt;
3257&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3258
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3259<p>The namespace value has to be an absolute URL, but the URL doesn't have to
3260point to any existing resource on the Web. It will bind all the element and
3261atributes with that URL. I suggest to use an URL within a domain you control,
3262and that the URL should contain some kind of version information if possible.
3263For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
3264namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3265
3266<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3267version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3268and if the version information don't match something you know, warn the user
3269and 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]3270namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3271same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3272associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3273just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3274<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3275prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3276
3277<p>@@Interfaces@@</p>
3278
3279<p>@@Examples@@</p>
3280
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3281<p>Usually people object to using namespaces together with validity checking.
3282I will try to make sure that using namespaces won't break validity checking,
3283so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3284suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3285<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3286flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3287from multiple DTDs will certainly break current validation schemes. I will
3288try to provide ways to do this, but this may not be portable or
3289standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3290
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3291<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3292
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3293<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3294
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3295<p>Version 2 of libxml is the first version introducing serious backward
3296incompatible changes. The main goals were:</p>
3297<ul>
3298 <li>a general cleanup. A number of mistakes inherited from the very early
3299 versions couldn't be changed due to compatibility constraints. Example
3300 the "childs" element in the nodes.</li>
3301 <li>Uniformization of the various nodes, at least for their header and link
3302 parts (doc, parent, children, prev, next), the goal is a simpler
3303 programming model and simplifying the task of the DOM implementors.</li>
3304 <li>better conformances to the XML specification, for example version 1.x
3305 had an heuristic to try to detect ignorable white spaces. As a result the
3306 SAX event generated were ignorableWhitespace() while the spec requires
3307 character() in that case. This also mean that a number of DOM node
3308 containing blank text may populate the DOM tree which were not present
3309 before.</li>
3310</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3311
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3312<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3313
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3314<p>So client code of libxml designed to run with version 1.x may have to be
3315changed to compile against version 2.x of libxml. Here is a list of changes
3316that I have collected, they may not be sufficient, so in case you find other
3317change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
3318mail</a>:</p>
3319<ol>
3320 <li>The package name have changed from libxml to libxml2, the library name
3321 is now -lxml2 . There is a new xml2-config script which should be used to
3322 select the right parameters libxml2</li>
3323 <li>Node <strong>childs</strong> field has been renamed
3324 <strong>children</strong> so s/childs/children/g should be applied
3325 (probablility of having "childs" anywere else is close to 0+</li>
3326 <li>The document don't have anymore a <strong>root</strong> element it has
3327 been replaced by <strong>children</strong> and usually you will get a
3328 list of element here. For example a Dtd element for the internal subset
3329 and it's declaration may be found in that list, as well as processing
3330 instructions or comments found before or after the document root element.
3331 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
3332 a document. Alternatively if you are sure to not reference Dtds nor have
3333 PIs or comments before or after the root element
3334 s/-&gt;root/-&gt;children/g will probably do it.</li>
3335 <li>The white space issue, this one is more complex, unless special case of
3336 validating parsing, the line breaks and spaces usually used for indenting
3337 and formatting the document content becomes significant. So they are
3338 reported by SAX and if your using the DOM tree, corresponding nodes are
3339 generated. Too approach can be taken:
3340 <ol>
3341 <li>lazy one, use the compatibility call
3342 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
3343 relying on a special (and possibly broken) set of heuristics of
3344 libxml to detect ignorable blanks. Don't complain if it breaks or
3345 make your application not 100% clean w.r.t. to it's input.</li>
3346 <li>the Right Way: change you code to accept possibly unsignificant
3347 blanks characters, or have your tree populated with weird blank text
3348 nodes. You can spot them using the comodity function
3349 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
3350 nodes.</li>
3351 </ol>
3352 <p>Note also that with the new default the output functions don't add any
3353 extra indentation when saving a tree in order to be able to round trip
3354 (read and save) without inflating the document with extra formatting
3355 chars.</p>
3356 </li>
3357 <li>The include path has changed to $prefix/libxml/ and the includes
3358 themselves uses this new prefix in includes instructions... If you are
3359 using (as expected) the
3360 <pre>xml2-config --cflags</pre>
3361 <p>output to generate you compile commands this will probably work out of
3362 the box</p>
3363 </li>
3364 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
3365 byte of the head of the document available for character detection.</li>
3366</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3367
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3368<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3369
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3370<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3371to allow smoth upgrade of existing libxml v1code while retaining
3372compatibility. They offers the following:</p>
3373<ol>
3374 <li>similar include naming, one should use
3375 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3376 <li>similar identifiers defined via macros for the child and root fields:
3377 respectively <strong>xmlChildrenNode</strong> and
3378 <strong>xmlRootNode</strong></li>
3379 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3380 inserted once in the client code</li>
3381</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3382
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3383<p>So the roadmap to upgrade your existing libxml applications is the
3384following:</p>
3385<ol>
3386 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3387 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3388 used and change it to <strong>xmlRootNode</strong></li>
3389 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3390 field is used and change it to <strong>xmlChildrenNode</strong></li>
3391 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3392 <strong>main()</strong> or in the library init entry point</li>
3393 <li>Recompile, check compatibility, it should still work</li>
3394 <li>Change your configure script to look first for xml2-config and fallback
3395 using xml-config . Use the --cflags and --libs ouptut of the command as
3396 the Include and Linking parameters needed to use libxml.</li>
3397 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3398 libxml-devel-1.8.y can be kept simultaneously)</li>
3399 <li>remove your config.cache, relaunch your configuration mechanism, and
3400 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3401 <li>Test that your application is still running correctly, if not this may
3402 be due to extra empty nodes due to formating spaces being kept in libxml2
3403 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3404 code before calling the parser (next to
3405 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3406</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3407
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3408<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]3409
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3410<p>Let me put some emphasis on the fact that there is far more changes from
3411libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3412has been considerably cleaned up and the conformance to the XML specification
3413has been drastically improved too. Don't take those changes as an excuse to
3414not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3415
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3416<h2><a name="Thread">Thread safety</a></h2>
3417
3418<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3419threads can safely work in parallel parsing different documents. There is
3420however a couple of things to do to ensure it:</p>
3421<ul>
3422 <li>configure the library accordingly using the --with-threads options</li>
3423 <li>call xmlInitParser() in the "main" thread before using any of the
3424 libxml API (except possibly selecting a different memory allocator)</li>
3425</ul>
3426
3427<p>Note that the thread safety cannot be ensured for multiple threads sharing
3428the same document, the locking must be done at the application level, libxml
3429exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3430The parts of the library checked for thread safety are:</p>
3431<ul>
3432 <li>concurrent loading</li>
3433 <li>file access resolution</li>
3434 <li>catalog access</li>
3435 <li>catalog building</li>
3436 <li>entities lookup/accesses</li>
3437 <li>validation</li>
3438 <li>global variables per-thread override</li>
3439 <li>memory handling</li>
3440</ul>
3441
3442<p>XPath is supposed to be thread safe now, but this wasn't tested
3443seriously.</p>
3444
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3445<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3446
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3447<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3448Object Model</em>; this is an API for accessing XML or HTML structured
3449documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3450and will be based on gnome-xml. This will be a far cleaner interface to
3451manipulate XML files within Gnome since it won't expose the internal
3452structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3453
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3454<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3455href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3456is a full DOM interface, thanks to Paolo Casarini, check the <a
3457href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3458informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3459
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3460<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3461
3462<p>Here is a real size example, where the actual content of the application
3463data 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]3464a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3465storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3466base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3467<pre>&lt;?xml version="1.0"?&gt;
3468&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3469 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3470
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3471 &lt;gjob:Job&gt;
3472 &lt;gjob:Project ID="3"/&gt;
3473 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3474 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3475
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3476 &lt;gjob:Update&gt;
3477 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3478 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3479 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3480 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3481
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3482 &lt;gjob:Developers&gt;
3483 &lt;gjob:Developer&gt;
3484 &lt;/gjob:Developer&gt;
3485 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3486
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3487 &lt;gjob:Contact&gt;
3488 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3489 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3490 &lt;gjob:Company&gt;
3491 &lt;/gjob:Company&gt;
3492 &lt;gjob:Organisation&gt;
3493 &lt;/gjob:Organisation&gt;
3494 &lt;gjob:Webpage&gt;
3495 &lt;/gjob:Webpage&gt;
3496 &lt;gjob:Snailmail&gt;
3497 &lt;/gjob:Snailmail&gt;
3498 &lt;gjob:Phone&gt;
3499 &lt;/gjob:Phone&gt;
3500 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3501
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3502 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3503 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3504 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3505
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3506 &lt;gjob:Skills&gt;
3507 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3508
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3509 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3510 A GNOME based system that will allow a superuser to configure
3511 compressed and uncompressed files and/or file systems to be backed
3512 up with a supported media in the system. This should be able to
3513 perform via find commands generating a list of files that are passed
3514 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3515 or via operations performed on the filesystem itself. Email
3516 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3517 &lt;/gjob:Details&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:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3520
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3521 &lt;/gjob:Jobs&gt;
3522&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3523
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3524<p>While loading the XML file into an internal DOM tree is a matter of
3525calling only a couple of functions, browsing the tree to gather the ata and
3526generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3527
3528<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3529structure. For example, the ordering of the attributes is not significant,
3530the 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]3531depend on the order of the children of a given node, unless it really makes
3532things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3533<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3534 * A person record
3535 */
3536typedef struct person {
3537 char *name;
3538 char *email;
3539 char *company;
3540 char *organisation;
3541 char *smail;
3542 char *webPage;
3543 char *phone;
3544} person, *personPtr;
3545
3546/*
3547 * And the code needed to parse it
3548 */
3549personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3550 personPtr ret = NULL;
3551
3552DEBUG("parsePerson\n");
3553 /*
3554 * allocate the struct
3555 */
3556 ret = (personPtr) malloc(sizeof(person));
3557 if (ret == NULL) {
3558 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3559 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3560 }
3561 memset(ret, 0, sizeof(person));
3562
3563 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3564 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3565 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3566 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3567 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3568 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3569 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3570 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3571 }
3572
3573 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3574}</pre>
3575
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3576<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3577<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3578 <li>Usually a recursive parsing style is the more convenient one: XML data
3579 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3580 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3581 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3582 i.e. the pointer to the global XML document and the namespace reserved to
3583 the application. Document wide information are needed for example to
3584 decode entities and it's a good coding practice to define a namespace for
3585 your application set of data and test that the element and attributes
3586 you're analyzing actually pertains to your application space. This is
3587 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3588 <li>To retrieve text and attributes value, you can use the function
3589 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3590 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3591</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3592
3593<p>Here is another piece of code used to parse another level of the
3594structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3595<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3596/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3597 * a Description for a Job
3598 */
3599typedef struct job {
3600 char *projectID;
3601 char *application;
3602 char *category;
3603 personPtr contact;
3604 int nbDevelopers;
3605 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3606} job, *jobPtr;
3607
3608/*
3609 * And the code needed to parse it
3610 */
3611jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3612 jobPtr ret = NULL;
3613
3614DEBUG("parseJob\n");
3615 /*
3616 * allocate the struct
3617 */
3618 ret = (jobPtr) malloc(sizeof(job));
3619 if (ret == NULL) {
3620 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3621 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3622 }
3623 memset(ret, 0, sizeof(job));
3624
3625 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3626 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3627 while (cur != NULL) {
3628
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3629 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3630 ret-&gt;projectID = xmlGetProp(cur, "ID");
3631 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3632 fprintf(stderr, "Project has no ID\n");
3633 }
3634 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3635 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3636 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3637 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3638 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3639 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3640 ret-&gt;contact = parsePerson(doc, ns, cur);
3641 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3642 }
3643
3644 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3645}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3646
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3647<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]3648boring. Ultimately, it could be possble to write stubbers taking either C
3649data structure definitions, a set of XML examples or an XML DTD and produce
3650the code needed to import and export the content between C data and XML
3651storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3652
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3653<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3654parsing example</a> as a template, it is also available with Makefile in the
3655Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3656
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3657<h2><a name="Contributi">Contributions</a></h2>
3658<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3659 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3660 patches, Gary Pennington worked on the validation API, threading support
3661 and Solaris port.</li>
3662 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3663 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3664 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3665 Website: <a
3666 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3667 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3668 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3669 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3670 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3671 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3672 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3673 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
Daniel Veillarddb9dfd92001-11-26 17:25:02 +0000[diff] [blame]3674 provides <a href="http://garypennington.net/libxml2/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3675 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3676 <li><a
3677 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3678 Sergeant</a>
3679 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3680 wrapper for libxml2/libxslt as part of the <a
3681 href="http://axkit.com/">AxKit XML application server</a></li>
3682 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3683 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3684 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3685 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3686 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3687 provided <a href="http://xmlsoft.org/messages/0488.html">man
3688 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3689 <li>there is a module for <a
3690 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3691 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3692 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3693 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3694 for Python</a></li>
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]3695 <li>Petr Kozelka provides <a
3696 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
3697 libxml2</a> with Kylix and Delphi and other Pascal compilers</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3698</ul>
3699
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3700<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3701</body>
3702</html>