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4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +00005 <title>The XML C library for Gnome</title>
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Daniel Veillardec78c0f2000-08-25 10:25:23 +000011<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +000012
Daniel Veillard9c466822001-10-25 12:03:39 +000013<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 +000016<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +000017
18<p></p>
Daniel Veillard9c466822001-10-25 12:03:39 +000019
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 +000028<ul>
Daniel Veillard9c466822001-10-25 12:03:39 +000029 <li>the XML standard: <a
30 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li>
31 <li>Namespaces in XML: <a
32 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li>
33 <li>XML Base: <a
34 href="http://www.w3.org/TR/xmlbase/">http://www.w3.org/TR/xmlbase/</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +000035 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a> :
36 Uniform Resource Identifiers <a
Daniel Veillard9c466822001-10-25 12:03:39 +000037 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li>
38 <li>XML Path Language (XPath) 1.0: <a
39 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li>
40 <li>HTML4 parser: <a
41 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li>
42 <li>most of XML Pointer Language (XPointer) Version 1.0: <a
43 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li>
44 <li>XML Inclusions (XInclude) Version 1.0: <a
45 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li>
46 <li>[ISO-8859-1], <a
47 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8]
48 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a>
49 [UTF-16] core encodings</li>
50 <li>part of SGML Open Technical Resolution TR9401:1997</li>
51 <li>XML Catalogs Working Draft 06 August 2001: <a
52 href="http://www.oasis-open.org/committees/entity/spec-2001-08-06.html">http://www.oasis-open.org/committees/entity/spec-2001-08-06.html</a></li>
Daniel Veillard5c396542002-03-15 07:57:50 +000053 <li>Canonical XML Version 1.0: <a
54 href="http://www.w3.org/TR/xml-c14n">http://www.w3.org/TR/xml-c14n</a>
Daniel Veillard2d347fa2002-03-17 10:34:11 +000055 and the Exclusive XML Canonicalization CR draft <a
56 href="http://www.w3.org/TR/xml-exc-c14n">http://www.w3.org/TR/xml-exc-c14n</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +000057</ul>
58
Daniel Veillard9c466822001-10-25 12:03:39 +000059<p>In most cases libxml tries to implement the specifications in a relatively
Daniel Veillarda5393562002-02-20 11:40:49 +000060strict way. As of release 2.4.16, libxml2 passes all 1800+ tests from the <a
61href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests
62Suite</a>.</p>
Daniel Veillard5b16f582002-02-20 11:38:46 +000063
64<p>To some extent libxml2 provide some support for the following other
65specification but don't claim to implement them:</p>
Daniel Veillard9c466822001-10-25 12:03:39 +000066<ul>
67 <li>Document Object Model (DOM) <a
68 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
69 it doesn't implement the API itself, gdome2 does this in top of
70 libxml2</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +000071 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a> :
72 libxml implements a basic FTP client code</li>
73 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a> :
74 HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +000075 <li>SAX: a minimal SAX implementation compatible with early expat
76 versions</li>
77 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
78 XML</li>
79</ul>
80
Daniel Veillard2d347fa2002-03-17 10:34:11 +000081<p>Libxml2 is known to be very portable, the library should build and work
82without serious troubles on a variety of systems (Linux, Unix, Windows,
83CygWin, MacOs, MacOsX, RISC Os, OS/2, VMS, QNX, MVS, ...)</p>
Daniel Veillard9c466822001-10-25 12:03:39 +000084
Daniel Veillard96984452000-08-31 13:50:12 +000085<p>Separate documents:</p>
86<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +000087 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a> providing an
Daniel Veillard2d347fa2002-03-17 10:34:11 +000088 implementation of XSLT 1.0 and common extensions like EXSLT for
89 libxml2</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +000090 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard2d347fa2002-03-17 10:34:11 +000091 : a standard DOM2 implementation for libxml2</li>
92 <li><a href="http://www.aleksey.com/xmlsec/">the XMLSec page</a>: an
93 implementation of <a href="http://www.w3.org/TR/xmldsig-core/">W3C XML
94 Digital Signature</a> for libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +000095</ul>
96
97<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +000098
Daniel Veillardf13e1ed2000-03-06 07:41:49 +000099<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000100href="http://www.w3.org/XML/">XML</a> C library developped for the <a
101href="http://www.gnome.org/">Gnome</a> project. <a
102href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
103structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000104
Daniel Veillard0142b842000-01-14 14:45:24 +0000105<p>Here are some key points about libxml:</p>
106<ul>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000107 <li>Libxml exports Push (progressive) and Pull (blocking) type parser
108 interfaces for both XML and HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000109 <li>Libxml can do DTD validation at parse time, using a parsed document
110 instance, or with an arbitrary DTD.</li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000111 <li>Libxml includes complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000112 href="http://www.w3.org/TR/xpath">XPath</a>, <a
113 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
114 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000115 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000116 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000117 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000118 <li>Basic support for HTTP and FTP client allowing aplications to fetch
119 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000120 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000121 <li>The internal document repesentation is as close as possible to the <a
122 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
123 <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
Daniel Veillard402e8c82000-02-29 22:57:47 +0000124 like interface</a>; the interface is designed to be compatible with <a
125 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardc575b992002-02-08 13:28:40 +0000126 <li>This library is released under the <a
127 href="http://www.opensource.org/licenses/mit-license.html">MIT
128 Licence</a> see the Copyright file in the distribution for the precise
129 wording.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000130</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000131
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000132<p>Warning: unless you are forced to because your application links with a
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000133Gnome-1.X library requiring it, <strong><span
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000134style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
135libxml2</p>
136
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000137<h2><a name="FAQ">FAQ</a></h2>
138
139<p>Table of Content:</p>
140<ul>
141 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
142 <li><a href="FAQ.html#Installati">Installation</a></li>
143 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
144 <li><a href="FAQ.html#Developer">Developer corner</a></li>
145</ul>
146
147<h3><a name="Licence">Licence</a>(s)</h3>
148<ol>
149 <li><em>Licensing Terms for libxml</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000150 <p>libxml is released under the <a
151 href="http://www.opensource.org/licenses/mit-license.html">MIT
152 Licence</a>, see the file Copyright in the distribution for the precise
153 wording</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000154 </li>
155 <li><em>Can I embed libxml in a proprietary application ?</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000156 <p>Yes. The MIT Licence allows you to also keep proprietary the changes
157 you made to libxml, but it would be graceful to provide back bugfixes and
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000158 improvements as patches for possible incorporation in the main
159 development tree</p>
160 </li>
161</ol>
162
163<h3><a name="Installati">Installation</a></h3>
164<ol>
165 <li>Unless you are forced to because your application links with a Gnome
166 library requiring it, <strong><span style="background-color: #FF0000">Do
167 Not Use libxml1</span></strong>, use libxml2</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000168 <li><em>Where can I get libxml</em> ?
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000169 <p>The original distribution comes from <a
170 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
171 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
172 <p>Most linux and Bsd distribution includes libxml, this is probably the
173 safer way for end-users</p>
174 <p>David Doolin provides precompiled Windows versions at <a
175 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
176 </li>
177 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
178 <ul>
179 <li>If you are not concerned by any existing backward compatibility
180 with existing application, install libxml2 only</li>
181 <li>If you are not doing development, you can safely install both.
182 usually the packages <a
183 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
184 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
185 compatible (this is not the case for development packages)</li>
186 <li>If you are a developer and your system provides separate packaging
187 for shared libraries and the development components, it is possible
188 to install libxml and libxml2, and also <a
189 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
190 and <a
191 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
192 too for libxml2 &gt;= 2.3.0</li>
193 <li>If you are developing a new application, please develop against
194 libxml2(-devel)</li>
195 </ul>
196 </li>
197 <li><em>I can't install the libxml package it conflicts with libxml0</em>
198 <p>You probably have an old libxml0 package used to provide the shared
199 library for libxml.so.0, you can probably safely remove it. Anyway the
200 libxml packages provided on <a
201 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
202 libxml.so.0</p>
203 </li>
204 <li><em>I can't install the libxml(2) RPM package due to failed
205 dependancies</em>
206 <p>The most generic solution is to refetch the latest src.rpm , and
207 rebuild it locally with</p>
208 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
209 <p>if everything goes well it will generate two binary rpm (one providing
210 the shared libs and xmllint, and the other one, the -devel package
211 providing includes, static libraries and scripts needed to build
212 applications with libxml(2)) that you can install locally.</p>
213 </li>
214</ol>
215
216<h3><a name="Compilatio">Compilation</a></h3>
217<ol>
218 <li><em>What is the process to compile libxml ?</em>
219 <p>As most UNIX libraries libxml follows the "standard":</p>
220 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
221 <p><code>cd libxml-xxxx</code></p>
222 <p><code>./configure --help</code></p>
223 <p>to see the options, then the compilation/installation proper</p>
224 <p><code>./configure [possible options]</code></p>
225 <p><code>make</code></p>
226 <p><code>make install</code></p>
227 <p>At that point you may have to rerun ldconfig or similar utility to
228 update your list of installed shared libs.</p>
229 </li>
230 <li><em>What other libraries are needed to compile/install libxml ?</em>
231 <p>Libxml does not requires any other library, the normal C ANSI API
232 should be sufficient (please report any violation to this rule you may
233 find).</p>
234 <p>However if found at configuration time libxml will detect and use the
235 following libs:</p>
236 <ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000237 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a> : a
238 highly portable and available widely compression library</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000239 <li>iconv: a powerful character encoding conversion library. It's
240 included by default on recent glibc libraries, so it doesn't need to
241 be installed specifically on linux. It seems it's now <a
242 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
243 of the official UNIX</a> specification. Here is one <a
244 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
245 of the library</a> which source can be found <a
246 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
247 </ul>
248 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000249 <li><em>make check fails on some platforms</em>
250 <p>Sometime the regression tests results don't completely match the value
251 produced by the parser, and the makefile uses diff to print the delta. On
252 some platforms the diff return breaks the compilation process, if the
Daniel Veillarde46182c2002-02-12 14:29:11 +0000253 diff is small this is probably not a serious problem.</p>
254 <p>Sometimes (especially on Solaris) make checks fails due to limitations
255 in make. Try using GNU-make instead.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000256 </li>
257 <li><em>I use the CVS version and there is no configure script</em>
258 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
259 script to regenerate the configure and Makefiles, like:</p>
260 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
261 </li>
262 <li><em>I have troubles when running make tests with gcc-3.0</em>
263 <p>It seems the initial release of gcc-3.0 has a problem with the
264 optimizer which miscompiles the URI module. Please use another
265 compiler</p>
266 </li>
267</ol>
268
269<h3><a name="Developer">Developer</a> corner</h3>
270<ol>
271 <li><em>xmlDocDump() generates output on one line</em>
272 <p>libxml will not <strong>invent</strong> spaces in the content of a
273 document since <strong>all spaces in the content of a document are
274 significant</strong>. If you build a tree from the API and want
275 indentation:</p>
276 <ol>
277 <li>the correct way is to generate those yourself too</li>
278 <li>the dangerous way is to ask libxml to add those blanks to your
279 content <strong>modifying the content of your document in the
280 process</strong>. The result may not be what you expect. There is
281 <strong>NO</strong> way to guarantee that such a modification won't
282 impact other part of the content of your document. See <a
283 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
284 ()</a> and <a
285 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
286 ()</a></li>
287 </ol>
288 </li>
289 <li>Extra nodes in the document:
290 <p><em>For a XML file as below:</em></p>
291 <pre>&lt;?xml version="1.0"?&gt;
292&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
293&lt;NODE CommFlag="0"/&gt;
294&lt;NODE CommFlag="1"/&gt;
295&lt;/PLAN&gt;</pre>
296 <p><em>after parsing it with the function
297 pxmlDoc=xmlParseFile(...);</em></p>
298 <p><em>I want to the get the content of the first node (node with the
299 CommFlag="0")</em></p>
300 <p><em>so I did it as following;</em></p>
301 <pre>xmlNodePtr pode;
302pnode=pxmlDoc-&gt;children-&gt;children;</pre>
303 <p><em>but it does not work. If I change it to</em></p>
304 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
305 <p><em>then it works. Can someone explain it to me.</em></p>
306 <p></p>
307 <p>In XML all characters in the content of the document are significant
308 <strong>including blanks and formatting line breaks</strong>.</p>
309 <p>The extra nodes you are wondering about are just that, text nodes with
310 the formatting spaces wich are part of the document but that people tend
311 to forget. There is a function <a
312 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
313 ()</a> to remove those at parse time, but that's an heuristic, and its
314 use should be limited to case where you are sure there is no
315 mixed-content in the document.</p>
316 </li>
317 <li><em>I get compilation errors of existing code like when accessing
318 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
319 <p>You are compiling code developed for libxml version 1 and using a
320 libxml2 development environment. Either switch back to libxml v1 devel or
321 even better fix the code to compile with libxml2 (or both) by <a
322 href="upgrade.html">following the instructions</a>.</p>
323 </li>
324 <li><em>I get compilation errors about non existing
325 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
326 fields</em>
327 <p>The source code you are using has been <a
328 href="upgrade.html">upgraded</a> to be able to compile with both libxml
329 and libxml2, but you need to install a more recent version:
330 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
331 </li>
332 <li><em>XPath implementation looks seriously broken</em>
333 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000334 a recent version, there is no known bug in the current version.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000335 </li>
336 <li><em>The example provided in the web page does not compile</em>
337 <p>It's hard to maintain the documentation in sync with the code
338 &lt;grin/&gt; ...</p>
339 <p>Check the previous points 1/ and 2/ raised before, and send
340 patches.</p>
341 </li>
342 <li><em>Where can I get more examples and informations than in the web
343 page</em>
344 <p>Ideally a libxml book would be nice. I have no such plan ... But you
345 can:</p>
346 <ul>
347 <li>check more deeply the <a href="html/libxml-lib.html">existing
348 generated doc</a></li>
349 <li>looks for examples of use for libxml function using the Gnome code
350 for example the following will query the full Gnome CVs base for the
351 use of the <strong>xmlAddChild()</strong> function:
352 <p><a
353 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
354 <p>This may be slow, a large hardware donation to the gnome project
355 could cure this :-)</p>
356 </li>
357 <li><a
358 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
Daniel Veillardaf43f632002-03-08 15:05:20 +0000359 the libxml source</a> , I try to write code as clean and documented
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000360 as possible, so looking at it may be helpful. Especially the code of
361 xmllint.c and of the various testXXX.c tests programs should provide
362 good example on how to do things with the library.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000363 </ul>
364 </li>
365 <li>What about C++ ?
366 <p>libxml is written in pure C in order to allow easy reuse on a number
367 of platforms, including embedded systems. I don't intend to convert to
368 C++.</p>
369 <p>There is however a C++ wrapper provided by Ari Johnson
370 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
371 <p>Website: <a
372 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
373 <p>Download: <a
374 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
375 </li>
376 <li>How to validate a document a posteriori ?
377 <p>It is possible to validate documents which had not been validated at
378 initial parsing time or documents who have been built from scratch using
379 the API. Use the <a
380 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
381 function. It is also possible to simply add a Dtd to an existing
382 document:</p>
383 <pre>xmlDocPtr doc; /* your existing document */
384 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
385 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
386
387 doc-&gt;intSubset = dtd;
388 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
389 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
390 </pre>
391 </li>
392 <li>etc ...</li>
393</ol>
394
395<p></p>
396
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000397<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000398
Daniel Veillard402e8c82000-02-29 22:57:47 +0000399<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000400<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000401 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000402 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000403 documentation</a> automatically extracted from code comments (using <a
404 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
405 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000406 <li>Look at the documentation about <a href="encoding.html">libxml
407 internationalization support</a></li>
Daniel Veillardbc66f852002-01-14 09:49:20 +0000408 <li>This page provides a global overview and <a href="example.html">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000409 examples</a> on how to use libxml.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000410 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000411 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
412 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000413 <li>George Lebl wrote <a
414 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000415 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000416 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
417 file</a></li>
418 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
419 starting a new project using libxml you should really use the 2.x
420 version.</li>
Daniel Veillard845cce42002-01-09 11:51:37 +0000421 <li>And don't forget to look at the <a
422 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000423</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000424
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000425<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000426
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000427<p>Well, bugs or missing features are always possible, and I will make a
428point of fixing them in a timely fashion. The best way to report a bug is to
429use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
430bug tracking database</a> (make sure to use the "libxml" module name). I look
431at reports there regularly and it's good to have a reminder when a bug is
Daniel Veillard51095312001-10-28 18:51:57 +0000432still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000433
Daniel Veillard0142b842000-01-14 14:45:24 +0000434<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000435href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
436href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000437href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
438please visit the <a
439href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
440follow the instructions. <strong>Do not send code, I won't debug it</strong>
441(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000442
Daniel Veillard008186f2001-09-13 14:24:44 +0000443<p>Check the following <strong><span style="color: #FF0000">before
444posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000445<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000446 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000447 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
448 version</a>, and that the problem still shows up in those</li>
449 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
450 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000451 there is probably a fix available, similary check the <a
452 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000453 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000454 <li>make sure you can reproduce the bug with xmllint or one of the test
455 programs found in source in the distribution</li>
456 <li>Please send the command showing the error as well as the input (as an
457 attachement)</li>
458</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000459
Daniel Veillarddadd0872001-09-15 09:21:44 +0000460<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000461href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000462related I will approve it.. Please do not send me mail directly, it makes
463things really harder to track and in some cases I'm not the best person to
464answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000465
Daniel Veillard91e9d582001-02-26 07:31:12 +0000466<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000467probably be processed faster.</p>
468
469<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000470href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000471provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000472questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000473documentantion</a> is not as polished as I would like (i need to learn more
474about Docbook), but it's a good starting point.</p>
475
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000476<h2><a name="help">How to help</a></h2>
477
478<p>You can help the project in various ways, the best thing to do first is to
479subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000480href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
481href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000482database:</a>:</p>
483<ol>
484 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000485 <li>provide the diffs when you port libxml to a new platform. They may not
Daniel Veillardab8500d2000-10-15 21:06:19 +0000486 be integrated in all cases but help pinpointing portability problems
487 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000488 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000489 as HTML diffs).</li>
490 <li>provide new documentations pieces (translations, examples, etc ...)</li>
491 <li>Check the TODO file and try to close one of the items</li>
492 <li>take one of the points raised in the archive or the bug database and
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000493 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
494 </a>before to avoid synchronization problems and check that the suggested
495 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000496</ol>
497
Daniel Veillard10a2c651999-12-12 13:03:50 +0000498<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000499
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000500<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000501href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
502href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
503href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000504href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000505as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000506archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000507href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
508packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000509href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
510href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000511packages installed to compile applications using libxml.) <a
512href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
513of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000514href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000515provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
Daniel Veillard1aadc442001-11-28 13:10:32 +0000516Pennington</a> provides <a href="http://garypennington.net/libxml2/">Solaris
517binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000518
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000519<p><a name="Snapshot">Snapshot:</a></p>
520<ul>
521 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000522 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000523 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000524 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000525</ul>
526
Daniel Veillardc6271d22001-10-27 07:50:58 +0000527<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000528
529<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000530platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000531languages have been provided, and can be found in the <a
532href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000533
Daniel Veillard82687162001-01-22 15:32:01 +0000534<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000535<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000536 <li><p>The <a
537 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000538 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000539 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
540 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000541 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000542 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000543</ul>
544
545<h2><a name="News">News</a></h2>
546
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000547<h3>CVS only : check the <a
548href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000549for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000550
Daniel Veillard91e9d582001-02-26 07:31:12 +0000551<p>Items floating around but not actively worked on, get in touch with me if
Daniel Veillardab8500d2000-10-15 21:06:19 +0000552you want to test those</p>
553<ul>
Daniel Veillard28929b22000-11-13 18:22:49 +0000554 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
555 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000556</ul>
557
558<h3>2.4.17: Mar 8 2002</h3>
559<ul>
560 <li>a lot of bug fixes, including "namespace nodes have no parents in
561 XPath"</li>
562 <li>fixed/improved the Python wrappers, added more examples and more
563 regression tests, XPath extension functions can now return node-sets</li>
564 <li>added the XML Canonalization support from Aleksey Sanin</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000565</ul>
566
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000567<h3>2.4.16: Feb 20 2002</h3>
568<ul>
569 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite
570 from OASIS and W3C. Compliance has been significantly improved.</li>
571 <li>a couple of portability fixes too.</li>
572</ul>
573
Daniel Veillard397ff112002-02-11 18:27:20 +0000574<h3>2.4.15: Feb 11 2002</h3>
575<ul>
576 <li>Fixed the Makefiles, especially the python module ones</li>
577 <li>A few bug fixes and cleanup</li>
578 <li>Includes cleanup</li>
579</ul>
580
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000581<h3>2.4.14: Feb 8 2002</h3>
582<ul>
583 <li>Change of Licence to the <a
584 href="http://www.opensource.org/licenses/mit-license.html">MIT
585 Licence</a> basisally for integration in XFree86 codebase, and removing
586 confusion around the previous dual-licencing</li>
587 <li>added Python bindings, beta software but should already be quite
588 complete</li>
589 <li>a large number of fixes and cleanups, especially for all tree
590 manipulations</li>
591 <li>cleanup of the headers, generation of a reference API definition in
592 XML</li>
593</ul>
594
595<h3>2.4.13: Jan 14 2002</h3>
Daniel Veillard744683d2002-01-14 17:30:20 +0000596<ul>
597 <li>update of the documentation: John Fleck and Charlie Bozeman</li>
598 <li>cleanup of timing code from Justin Fletcher</li>
599 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei
600 Narojnyi</li>
601 <li>Cygwin patch from Robert Collins</li>
602 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li>
603</ul>
604
Daniel Veillardef90ba72001-12-07 14:24:22 +0000605<h3>2.4.12: Dec 7 2001</h3>
606<ul>
607 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman),
608 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups
609 (robert)</li>
610 <li>Eric Lavigne contributed project files for MacOS</li>
611 <li>some makefiles cleanups</li>
612</ul>
613
Daniel Veillarda4871052001-11-26 13:19:48 +0000614<h3>2.4.11: Nov 26 2001</h3>
615<ul>
616 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
617 cleanups</li>
618 <li>xmllint man pages improvement by Heiko Rupp</li>
619 <li>updated VMS build instructions from John A Fotheringham</li>
620 <li>Windows Makefiles updates from Igor</li>
621</ul>
622
Daniel Veillard43d3f612001-11-10 11:57:23 +0000623<h3>2.4.10: Nov 10 2001</h3>
624<ul>
625 <li>URI escaping fix (Joel Young)</li>
626 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
627 <li>Fixes namespace handling problems when using DTD and validation</li>
628 <li>improvements on xmllint: Morus Walter patches for --format and
629 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
630 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
631 <li>fixes to the HTML parser</li>
632</ul>
633
634<h3>2.4.9: Nov 6 2001</h3>
635<ul>
636 <li>fixes more catalog bugs</li>
637 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
638</ul>
639
Daniel Veillarded421aa2001-11-04 21:22:45 +0000640<h3>2.4.8: Nov 4 2001</h3>
641<ul>
642 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
643 tool</li>
644 <li>fixed a compile errors and some includes troubles.</li>
645</ul>
646
Daniel Veillard52dcab32001-10-30 12:51:17 +0000647<h3>2.4.7: Oct 30 2001</h3>
648<ul>
649 <li>exported some debugging interfaces</li>
650 <li>serious rewrite of the catalog code</li>
651 <li>integrated Gary Pennington thread safety patch, added configure option
652 and regression tests</li>
653 <li>removed an HTML parser bug</li>
654 <li>fixed a couple of potentially serious validation bugs</li>
655 <li>integrated the SGML DocBook support in xmllint</li>
656 <li>changed the nanoftp anonymous login passwd</li>
657 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
658 <li>general bug fixes</li>
659 <li>updated xmllint man page by John Fleck</li>
660 <li>some VMS and Windows updates</li>
661</ul>
662
Daniel Veillard60087f32001-10-10 09:45:09 +0000663<h3>2.4.6: Oct 10 2001</h3>
664<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000665 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000666 <li>portability and configure fixes</li>
667 <li>an infinite loop on the HTML parser was removed (William)</li>
668 <li>Windows makefile patches from Igor</li>
669 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
670 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
671</ul>
672
Daniel Veillarddadd0872001-09-15 09:21:44 +0000673<h3>2.4.5: Sep 14 2001</h3>
674<ul>
675 <li>Remove a few annoying bugs in 2.4.4</li>
676 <li>forces the HTML serializer to output decimal charrefs since some
677 version of Netscape can't handle hexadecimal ones</li>
678</ul>
679
680<h3>1.8.16: Sep 14 2001</h3>
681<ul>
682 <li>maintenance release of the old libxml1 branch, couple of bug and
683 portability fixes</li>
684</ul>
685
Daniel Veillard04382ae2001-09-12 18:51:30 +0000686<h3>2.4.4: Sep 12 2001</h3>
687<ul>
688 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
689 Catalog</li>
690 <li>a few bug fixes and some portability changes</li>
691 <li>some documentation cleanups</li>
692</ul>
693
Daniel Veillard39936902001-08-24 00:49:01 +0000694<h3>2.4.3: Aug 23 2001</h3>
695<ul>
696 <li>XML Catalog support see the doc</li>
697 <li>New NaN/Infinity floating point code</li>
698 <li>A few bug fixes</li>
699</ul>
700
701<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000702<ul>
703 <li>adds xmlLineNumbersDefault() to control line number generation</li>
704 <li>lot of bug fixes</li>
705 <li>the Microsoft MSC projects files shuld now be up to date</li>
706 <li>inheritance of namespaces from DTD defaulted attributes</li>
707 <li>fixes a serious potential security bug</li>
708 <li>added a --format option to xmllint</li>
709</ul>
710
711<h3>2.4.1: July 24 2001</h3>
712<ul>
713 <li>possibility to keep line numbers in the tree</li>
714 <li>some computation NaN fixes</li>
715 <li>extension of the XPath API</li>
716 <li>cleanup for alpha and ia64 targets</li>
717 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000718</ul>
719
720<h3>2.4.0: July 10 2001</h3>
721<ul>
722 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
723 <li>Fixed XML Base implementation, added a coupel of examples to the
724 regression tests</li>
725 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000726</ul>
727
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000728<h3>2.3.14: July 5 2001</h3>
729<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000730 <li>fixed some entities problems and reduce mem requirement when
731 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000732 <li>lots of improvements in the XPath queries interpreter can be
733 substancially faster</li>
734 <li>Makefiles and configure cleanups</li>
735 <li>Fixes to XPath variable eval, and compare on empty node set</li>
736 <li>HTML tag closing bug fixed</li>
737 <li>Fixed an URI reference computating problem when validating</li>
738</ul>
739
Daniel Veillard2adbb512001-06-28 16:20:36 +0000740<h3>2.3.13: June 28 2001</h3>
741<ul>
742 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
743 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
744</ul>
745
746<h3>1.8.14: June 28 2001</h3>
747<ul>
748 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
749 <li>Small Makefile fix</li>
750</ul>
751
Daniel Veillard11648102001-06-26 16:08:24 +0000752<h3>2.3.12: June 26 2001</h3>
753<ul>
754 <li>lots of cleanup</li>
755 <li>a couple of validation fix</li>
756 <li>fixed line number counting</li>
757 <li>fixed serious problems in the XInclude processing</li>
758 <li>added support for UTF8 BOM at beginning of entities</li>
759 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
760 miscompile uri.c (William), Thomas Leitner provided a fix for the
761 optimizer on Tru64</li>
762 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
763 compilation on Windows MSC</li>
764 <li>update of libxml-doc.el (Felix Natter)</li>
765 <li>fixed 2 bugs in URI normalization code</li>
766</ul>
767
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000768<h3>2.3.11: June 17 2001</h3>
769<ul>
770 <li>updates to trio, Makefiles and configure should fix some portability
771 problems (alpha)</li>
772 <li>fixed some HTML serialization problems (pre, script, and block/inline
773 handling), added encoding aware APIs, cleanup of this code</li>
774 <li>added xmlHasNsProp()</li>
775 <li>implemented a specific PI for encoding support in the DocBook SGML
776 parser</li>
777 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
778 node selection)</li>
779 <li>fixed a performance problem and an error in the validation code</li>
780 <li>fixed XInclude routine to implement the recursive behaviour</li>
781 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
782 <li>added --version to xmllint for bug reports</li>
783</ul>
784
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000785<h3>2.3.10: June 1 2001</h3>
786<ul>
787 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000788 <li>a number of reported bugs got fixed, in XPath, iconv detection,
789 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000790 <li>XPath string function should now handle unicode correctly</li>
791</ul>
792
Daniel Veillard4623acd2001-05-19 15:13:15 +0000793<h3>2.3.9: May 19 2001</h3>
794
795<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
796<ul>
797 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
798 <li>some serious speed optimisation again</li>
799 <li>some documentation cleanups</li>
800 <li>trying to get better linking on solaris (-R)</li>
801 <li>XPath API cleanup from Thomas Broyer</li>
802 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
803 xmlValidGetValidElements()</li>
804 <li>Added an INSTALL file</li>
805 <li>Attribute removal added to API: #54433</li>
806 <li>added a basic support for SGML catalogs</li>
807 <li>fixed xmlKeepBlanksDefault(0) API</li>
808 <li>bugfix in xmlNodeGetLang()</li>
809 <li>fixed a small configure portability problem</li>
810 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
811</ul>
812
Daniel Veillarda265af72001-05-14 11:13:58 +0000813<h3>1.8.13: May 14 2001</h3>
814<ul>
815 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
816</ul>
817
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000818<h3>2.3.8: May 3 2001</h3>
819<ul>
820 <li>Integrated an SGML DocBook parser for the Gnome project</li>
821 <li>Fixed a few things in the HTML parser</li>
822 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
823 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000824 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
825 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000826 <li>incorporated more Windows cleanup</li>
827 <li>added xmlSaveFormatFile()</li>
828 <li>fixed problems in copying nodes with entities references (gdome)</li>
829 <li>removed some troubles surrounding the new validation module</li>
830</ul>
831
Daniel Veillarda41123c2001-04-22 19:31:20 +0000832<h3>2.3.7: April 22 2001</h3>
833<ul>
834 <li>lots of small bug fixes, corrected XPointer</li>
835 <li>Non determinist content model validation support</li>
836 <li>added xmlDocCopyNode for gdome2</li>
837 <li>revamped the way the HTML parser handles end of tags</li>
838 <li>XPath: corrctions of namespacessupport and number formatting</li>
839 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
840 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
841 <li>Improved validation speed sensible for DocBook</li>
842 <li>fixed a big bug with ID declared in external parsed entities</li>
843 <li>portability fixes, update of Trio from Bjorn Reese</li>
844</ul>
845
Daniel Veillardafc73112001-04-11 11:51:41 +0000846<h3>2.3.6: April 8 2001</h3>
847<ul>
848 <li>Code cleanup using extreme gcc compiler warning options, found and
849 cleared half a dozen potential problem</li>
850 <li>the Eazel team found an XML parser bug</li>
851 <li>cleaned up the user of some of the string formatting function. used the
852 trio library code to provide the one needed when the platform is missing
853 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000854 <li>xpath: removed a memory leak and fixed the predicate evaluation
855 problem, extended the testsuite and cleaned up the result. XPointer seems
856 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000857</ul>
858
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000859<h3>2.3.5: Mar 23 2001</h3>
860<ul>
861 <li>Biggest change is separate parsing and evaluation of XPath expressions,
862 there is some new APIs for this too</li>
863 <li>included a number of bug fixes(XML push parser, 51876, notations,
864 52299)</li>
865 <li>Fixed some portability issues</li>
866</ul>
867
Daniel Veillarde356c282001-03-10 12:32:04 +0000868<h3>2.3.4: Mar 10 2001</h3>
869<ul>
870 <li>Fixed bugs #51860 and #51861</li>
871 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
872 size to be application tunable.</li>
873 <li>Some cleanup in the validation code, still a bug left and this part
874 should probably be rewritten to support ambiguous content model :-\</li>
875 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
876 parser</li>
877 <li>Fixed another bug in xmlNodeGetContent()</li>
878 <li>Bjorn fixed XPath node collection and Number formatting</li>
879 <li>Fixed a loop reported in the HTML parsing</li>
880 <li>blank space are reported even if the Dtd content model proves that they
881 are formatting spaces, this is for XmL conformance</li>
882</ul>
883
Daniel Veillardb402c072001-03-01 17:28:58 +0000884<h3>2.3.3: Mar 1 2001</h3>
885<ul>
886 <li>small change in XPath for XSLT</li>
887 <li>documentation cleanups</li>
888 <li>fix in validation by Gary Pennington</li>
889 <li>serious parsing performances improvements</li>
890</ul>
891
Daniel Veillardec70e912001-02-26 20:10:45 +0000892<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000893<ul>
894 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
895 <li>fixed a Dtd parsing bug</li>
896 <li>fixed a bug in xmlNodeGetContent</li>
897 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
898</ul>
899
Daniel Veillardec70e912001-02-26 20:10:45 +0000900<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000901<ul>
902 <li>some XPath and HTML bug fixes for XSLT</li>
903 <li>small extension of the hash table interfaces for DOM gdome2
904 implementation</li>
905 <li>A few bug fixes</li>
906</ul>
907
Daniel Veillardec70e912001-02-26 20:10:45 +0000908<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 +0000909<ul>
910 <li>Lots of XPath bug fixes</li>
911 <li>Add a mode with Dtd lookup but without validation error reporting for
912 XSLT</li>
913 <li>Add support for text node without escaping (XSLT)</li>
914 <li>bug fixes for xmlCheckFilename</li>
915 <li>validation code bug fixes from Gary Pennington</li>
916 <li>Patch from Paul D. Smith correcting URI path normalization</li>
917 <li>Patch to allow simultaneous install of libxml-devel and
918 libxml2-devel</li>
919 <li>the example Makefile is now fixed</li>
920 <li>added HTML to the RPM packages</li>
921 <li>tree copying bugfixes</li>
922 <li>updates to Windows makefiles</li>
923 <li>optimisation patch from Bjorn Reese</li>
924</ul>
925
Daniel Veillardec70e912001-02-26 20:10:45 +0000926<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000927<ul>
928 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
929 <li>added htmlHandleOmittedElem()</li>
930 <li>Applied Bjorn Reese's IPV6 first patch</li>
931 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000932 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000933</ul>
934
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000935<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000936<ul>
937 <li>Fix the Windows problems of 2.2.8</li>
938 <li>integrate OpenVMS patches</li>
939 <li>better handling of some nasty HTML input</li>
940 <li>Improved the XPointer implementation</li>
941 <li>integrate a number of provided patches</li>
942</ul>
943
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000944<h3>2.2.9: Nov 25 2000</h3>
945<ul>
946 <li>erroneous release :-(</li>
947</ul>
948
Daniel Veillard28929b22000-11-13 18:22:49 +0000949<h3>2.2.8: Nov 13 2000</h3>
950<ul>
951 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
952 support</li>
953 <li>Patch in conditional section handling</li>
954 <li>updated MS compiler project</li>
955 <li>fixed some XPath problems</li>
956 <li>added an URI escaping function</li>
957 <li>some other bug fixes</li>
958</ul>
959
960<h3>2.2.7: Oct 31 2000</h3>
961<ul>
962 <li>added message redirection</li>
963 <li>XPath improvements (thanks TOM !)</li>
964 <li>xmlIOParseDTD() added</li>
965 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
966 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
967</ul>
968
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000969<h3>2.2.6: Oct 25 2000:</h3>
970<ul>
971 <li>Added an hash table module, migrated a number of internal structure to
972 those</li>
973 <li>Fixed a posteriori validation problems</li>
974 <li>HTTP module cleanups</li>
975 <li>HTML parser improvements (tag errors, script/style handling, attribute
976 normalization)</li>
977 <li>coalescing of adjacent text nodes</li>
978 <li>couple of XPath bug fixes, exported the internal API</li>
979</ul>
980
Daniel Veillardab8500d2000-10-15 21:06:19 +0000981<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000982<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000983 <li>XPointer implementation and testsuite</li>
984 <li>Lot of XPath fixes, added variable and functions registration, more
985 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000986 <li>Portability fixes, lots of enhancements toward an easy Windows build
987 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000988 <li>Late validation fixes</li>
989 <li>Integrated a lot of contributed patches</li>
990 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000991 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000992</ul>
993
994<h3>2.2.4: Oct 1 2000:</h3>
995<ul>
996 <li>main XPath problem fixed</li>
997 <li>Integrated portability patches for Windows</li>
998 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000999</ul>
1000
Daniel Veillardd5f97f82000-09-17 16:38:14 +00001001<h3>2.2.3: Sep 17 2000</h3>
1002<ul>
1003 <li>bug fixes</li>
1004 <li>cleanup of entity handling code</li>
1005 <li>overall review of all loops in the parsers, all sprintf usage has been
1006 checked too</li>
1007 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
1008 works smoothly now.</li>
1009</ul>
1010
1011<h3>1.8.10: Sep 6 2000</h3>
1012<ul>
1013 <li>bug fix release for some Gnome projects</li>
1014</ul>
1015
1016<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +00001017<ul>
1018 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +00001019 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +00001020</ul>
1021
Daniel Veillardd5f97f82000-09-17 16:38:14 +00001022<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +00001023<ul>
1024 <li>a purely bug fixes release</li>
1025 <li>fixed an encoding support problem when parsing from a memory block</li>
1026 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001027 <li>removed a bug in the function allowing to override the memory
1028 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +00001029</ul>
1030
Daniel Veillardd5f97f82000-09-17 16:38:14 +00001031<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +00001032<ul>
1033 <li>applied a lot of portability fixes</li>
1034 <li>better encoding support/cleanup and saving (content is now always
1035 encoded in UTF-8)</li>
1036 <li>the HTML parser now correctly handles encodings</li>
1037 <li>added xmlHasProp()</li>
1038 <li>fixed a serious problem with &amp;#38;</li>
1039 <li>propagated the fix to FTP client</li>
1040 <li>cleanup, bugfixes, etc ...</li>
1041 <li>Added a page about <a href="encoding.html">libxml Internationalization
1042 support</a></li>
1043</ul>
1044
Daniel Veillard60979bd2000-07-10 12:17:33 +00001045<h3>1.8.9: July 9 2000</h3>
1046<ul>
1047 <li>fixed the spec the RPMs should be better</li>
1048 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
1049 rpmfind users problem</li>
1050</ul>
1051
Daniel Veillard6388e172000-07-03 16:07:19 +00001052<h3>2.1.1: July 1 2000</h3>
1053<ul>
1054 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1055 <li>improvements on the HTML parser</li>
1056</ul>
1057
Daniel Veillard3f6f7f62000-06-30 17:58:25 +00001058<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1059<ul>
1060 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1061 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1062 about &amp;#38; charref parsing</li>
1063 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1064 also contains numerous fixes and enhancements:
1065 <ul>
1066 <li>added xmlStopParser() to stop parsing</li>
1067 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1068 <li>includes XPath patches provided by Picdar Technology</li>
1069 <li>tried to fix as much as possible DtD validation and namespace
1070 related problems</li>
1071 <li>output to a given encoding has been added/tested</li>
1072 <li>lot of various fixes</li>
1073 </ul>
1074 </li>
1075</ul>
1076
Daniel Veillarde0aed302000-04-16 08:52:20 +00001077<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +00001078<ul>
1079 <li>First public release of libxml2. If you are using libxml, it's a good
Daniel Veillarde0aed302000-04-16 08:52:20 +00001080 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1081 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1082 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +00001083 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +00001084 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +00001085 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +00001086 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +00001087 <pre>#include "xxx.h"</pre>
1088 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +00001089 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1090 <li>the memory allocation routines used by libxml can now be overloaded
1091 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +00001092 <li>The previously CVS only tool tester has been renamed
1093 <strong>xmllint</strong> and is now installed as part of the libxml2
1094 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +00001095 <li>The I/O interface has been revamped. There is now ways to plug in
1096 specific I/O modules, either at the URI scheme detection level using
1097 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1098 parser context using xmlCreateIOParserCtxt()</li>
1099 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1100 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001101 <li>a number of optional features of libxml can now be excluded at
1102 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +00001103</ul>
1104
1105<h3>2.0.0beta: Mar 14 2000</h3>
1106<ul>
1107 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +00001108 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1109 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1110 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +00001111 <li>This version is now the head in the Gnome CVS base, the old one is
1112 available under the tag LIB_XML_1_X</li>
1113 <li>This includes a very large set of changes. Froma programmatic point of
1114 view applications should not have to be modified too much, check the <a
1115 href="upgrade.html">upgrade page</a></li>
1116 <li>Some interfaces may changes (especially a bit about encoding).</li>
1117 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +00001118 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +00001119 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1120 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001121 <li>Better handling of entities, especially well formedness checking
1122 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +00001123 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001124 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +00001125 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1126 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +00001127 </ul>
1128 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +00001129 <li>Serious progress were made toward compliance, <a
1130 href="conf/result.html">here are the result of the test</a> against the
1131 OASIS testsuite (except the japanese tests since I don't support that
1132 encoding yet). This URL is rebuilt every couple of hours using the CVS
1133 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +00001134</ul>
1135
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001136<h3>1.8.7: Mar 6 2000</h3>
1137<ul>
1138 <li>This is a bug fix release:</li>
1139 <li>It is possible to disable the ignorable blanks heuristic used by
1140 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001141 that for adherence to XML spec, this behaviour will be disabled by
1142 default in 2.x . The same function will allow to keep compatibility for
1143 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +00001144 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1145 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001146 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1147 compilation on some platforms has been fixed</li>
1148 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1149 URIs</li>
1150</ul>
1151
Daniel Veillarde41f2b72000-01-30 20:00:07 +00001152<h3>1.8.6: Jan 31 2000</h3>
1153<ul>
1154 <li>added a nanoFTP transport module, debugged until the new version of <a
1155 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1156 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +00001157</ul>
1158
1159<h3>1.8.5: Jan 21 2000</h3>
1160<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +00001161 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001162 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1163 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +00001164 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +00001165 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1166 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +00001167 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1168 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +00001169</ul>
1170
1171<h3>1.8.4: Jan 13 2000</h3>
1172<ul>
1173 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1174 <li>all exit() call should have been removed from libxml</li>
1175 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1176 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +00001177</ul>
1178
1179<h3>1.8.3: Jan 5 2000</h3>
1180<ul>
1181 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001182 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +00001183 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +00001184 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +00001185 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1186 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +00001187 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +00001188 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +00001189 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +00001190</ul>
1191
1192<h3>1.8.2: Dec 21 1999</h3>
1193<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +00001194 <li>I got another problem with includes and C++, I hope this issue is fixed
1195 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +00001196 <li>Added a few tree modification functions: xmlReplaceNode,
1197 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1198 xmlDocSetRootElement</li>
1199 <li>Tried to improve the HTML output with help from <a
1200 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +00001201</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +00001202
Daniel Veillarde4e51311999-12-18 15:32:46 +00001203<h3>1.8.1: Dec 18 1999</h3>
1204<ul>
1205 <li>various patches to avoid troubles when using libxml with C++ compilers
1206 the "namespace" keyword and C escaping in include files</li>
1207 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1208 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1209 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +00001210 <li>fixed a posteriori validation (validation after parsing, or by using a
1211 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +00001212 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +00001213</ul>
1214
1215<h3>1.8.0: Dec 12 1999</h3>
1216<ul>
1217 <li>cleanup, especially memory wise</li>
1218 <li>the parser should be more reliable, especially the HTML one, it should
1219 not crash, whatever the input !</li>
1220 <li>Integrated various patches, especially a speedup improvement for large
1221 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1222 configure with --with-buffers to enable them.</li>
1223 <li>attribute normalization, oops should have been added long ago !</li>
1224 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1225 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +00001226</ul>
Daniel Veillard35008381999-10-25 13:15:52 +00001227
1228<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001229<ul>
Daniel Veillard35008381999-10-25 13:15:52 +00001230 <li>Lots of HTML improvement</li>
1231 <li>Fixed some errors when saving both XML and HTML</li>
1232 <li>More examples, the regression tests should now look clean</li>
1233 <li>Fixed a bug with contiguous charref</li>
1234</ul>
1235
1236<h3>1.7.3: Sep 29 1999</h3>
1237<ul>
1238 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001239 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +00001240 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001241</ul>
1242
1243<h3>1.7.1: Sep 24 1999</h3>
1244<ul>
1245 <li>The basic type for strings manipulated by libxml has been renamed in
1246 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001247 is that CHAR was conflicting with a predefined type on Windows. However
1248 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001249 <strong>#define </strong>.</li>
1250 <li>Changed another error : the use of a structure field called errno, and
1251 leading to troubles on platforms where it's a macro</li>
1252</ul>
1253
1254<h3>1.7.0: sep 23 1999</h3>
1255<ul>
1256 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +00001257 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001258 <li>Added an errno to report errors by another mean than a simple printf
1259 like callback</li>
1260 <li>Finished ID/IDREF support and checking when validation</li>
1261 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +00001262 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001263 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1264 implementation</li>
1265 <li>Added an HTML parser front-end</li>
1266</ul>
1267
1268<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001269
Daniel Veillard402e8c82000-02-29 22:57:47 +00001270<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001271markup-based structured documents. Here is <a name="example">an example XML
1272document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00001273<pre>&lt;?xml version="1.0"?&gt;
1274&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1275 &lt;head&gt;
1276 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1277 &lt;/head&gt;
1278 &lt;chapter&gt;
1279 &lt;title&gt;The Linux adventure&lt;/title&gt;
1280 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1281 &lt;image href="linus.gif"/&gt;
1282 &lt;p&gt;...&lt;/p&gt;
1283 &lt;/chapter&gt;
1284&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +00001285
Daniel Veillard402e8c82000-02-29 22:57:47 +00001286<p>The first line specifies that it's an XML document and gives useful
1287information about its encoding. Then the document is a text format whose
1288structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001289to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001290(no content), a single tag can serve as both the opening and closing tag if
1291it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1292that, for example, the image tag has no content (just an attribute) and is
1293closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +00001294
Daniel Veillard402e8c82000-02-29 22:57:47 +00001295<p>XML can be applied sucessfully to a wide range of uses, from long term
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001296structured document maintenance (where it follows the steps of SGML) to
1297simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001298spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1299it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001300
Daniel Veillard82687162001-01-22 15:32:01 +00001301<h2><a name="XSLT">XSLT</a></h2>
1302
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +00001303<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1304
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001305<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1306language for transforming XML documents into other XML documents (or
1307HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +00001308
1309<p>A separate library called libxslt is being built on top of libxml2. This
1310module "libxslt" can be found in the Gnome CVS base too.</p>
1311
Daniel Veillard383b1472001-01-23 11:39:52 +00001312<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001313href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1314supported and the progresses on the <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001315href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog"
1316name="Changelog">Changelog</a></p>
1317
1318<h2><a name="Python">Python and bindings</a></h2>
1319
1320<p>There is a number of language bindings and wrappers available for libxml2,
1321the list below is not exhaustive. Please contact the <a
1322href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
1323(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
1324order to get updates to this list or to discuss the specific topic of libxml2
1325or libxslt wrappers or bindings:</p>
1326<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +00001327 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
1328 for libxml:<br>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001329 Website: <a
1330 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
1331 Download: <a
1332 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
1333 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
1334 based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
1335 <li><a
1336 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +00001337 Sergeant</a> developped <a
1338 href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
1339 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
1340 application server</a></li>
1341 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
1342 earlier version of the libxml/libxslt <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001343 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
1344 <li>Petr Kozelka provides <a
1345 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
1346 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
1347 <li>Wai-Sun "Squidster" Chia provides <a
1348 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
1349 libxml2 bindings are also available in Ruby through the <a
1350 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
1351 maintained by Tobias Peters.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +00001352 <li>Steve Ball and contributors maintains <a
1353 href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
1354 Tcl</a></li>
1355 <li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001356</ul>
1357
1358<p>The distribution includes a set of Python bindings, which are garanteed to
1359be maintained as part of the library in the future, though the Python
Daniel Veillard0b79dfe2002-02-23 13:02:31 +00001360interface have not yet reached the maturity of the C API.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +00001361
1362<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +00001363<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +00001364 <li>If you use an RPM based distribution, simply install the <a
1365 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python
1366 RPM</a> (and if needed the <a
1367 href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
1368 RPM</a>).</li>
1369 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
1370 module distribution</a> corresponding to your installed version of
1371 libxml2 and libxslt. Note that to install it you will need both libxml2
1372 and libxslt installed and run "python setup.py build install" in the
1373 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +00001374</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +00001375
1376<p>The distribution includes a set of examples and regression tests for the
1377python bindings in the <code>python/tests</code> directory. Here are some
1378excepts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001379
1380<h3>tst.py:</h3>
1381
1382<p>This is a basic test of the file interface and DOM navigation:</p>
1383<pre>import libxml2
1384
1385doc = libxml2.parseFile("tst.xml")
1386if doc.name != "tst.xml":
1387 print "doc.name failed"
1388 sys.exit(1)
1389root = doc.children
1390if root.name != "doc":
1391 print "root.name failed"
1392 sys.exit(1)
1393child = root.children
1394if child.name != "foo":
1395 print "child.name failed"
1396 sys.exit(1)
1397doc.freeDoc()</pre>
1398
1399<p>The Python module is called libxml2, parseFile is the equivalent of
1400xmlParseFile (most of the bindings are automatically generated, and the xml
1401prefix is removed and the casing convention are kept). All node seen at the
1402binding level share the same subset of accesors:</p>
1403<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +00001404 <li><code>name</code> : returns the node name</li>
1405 <li><code>type</code> : returns a string indicating the node
1406 typ<code>e</code></li>
1407 <li><code>content</code> : returns the content of the node, it is based on
1408 xmlNodeGetContent() and hence is recursive.</li>
1409 <li><code>parent</code> , <code>children</code>, <code>last</code>,
1410 <code>next</code>, <code>prev</code>, <code>doc</code>,
1411 <code>properties</code>: pointing to the associated element in the tree,
1412 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001413</ul>
1414
1415<p>Also note the need to explicitely deallocate documents with freeDoc() .
1416Reference counting for libxml2 trees would need quite a lot of work to
1417function properly, and rather than risk memory leaks if not implemented
1418correctly it sounds safer to have an explicit function to free a tree. The
1419wrapper python objects like doc, root or child are them automatically garbage
1420collected.</p>
1421
1422<h3>validate.py:</h3>
1423
1424<p>This test check the validation interfaces and redirection of error
1425messages:</p>
1426<pre>import libxml2
1427
1428#desactivate error messages from the validation
1429def noerr(ctx, str):
1430 pass
1431
1432libxml2.registerErrorHandler(noerr, None)
1433
1434ctxt = libxml2.createFileParserCtxt("invalid.xml")
1435ctxt.validate(1)
1436ctxt.parseDocument()
1437doc = ctxt.doc()
1438valid = ctxt.isValid()
1439doc.freeDoc()
1440if valid != 0:
1441 print "validity chec failed"</pre>
1442
1443<p>The first thing to notice is the call to registerErrorHandler(), it
1444defines a new error handler global to the library. It is used to avoid seeing
1445the error messages when trying to validate the invalid document.</p>
1446
1447<p>The main interest of that test is the creation of a parser context with
1448createFileParserCtxt() and how the behaviour can be changed before calling
1449parseDocument() . Similary the informations resulting from the parsing phase
1450are also available using context methods.</p>
1451
1452<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
1453C function interfaces in terms of objects method as much as possible. The
1454best to get a complete view of what methods are supported is to look at the
1455libxml2.py module containing all the wrappers.</p>
1456
1457<h3>push.py:</h3>
1458
1459<p>This test show how to activate the push parser interface:</p>
1460<pre>import libxml2
1461
1462ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
1463ctxt.parseChunk("/&gt;", 2, 1)
1464doc = ctxt.doc()
1465
1466doc.freeDoc()</pre>
1467
1468<p>The context is created with a speciall call based on the
1469xmlCreatePushParser() from the C library. The first argument is an optional
1470SAX callback object, then the initial set of data, the lenght and the name of
1471the resource in case URI-References need to be computed by the parser.</p>
1472
1473<p>Then the data are pushed using the parseChunk() method, the last call
1474setting the thrird argument terminate to 1.</p>
1475
1476<h3>pushSAX.py:</h3>
1477
1478<p>this test show the use of the event based parsing interfaces. In this case
1479the parser does not build a document, but provides callback information as
1480the parser makes progresses analyzing the data being provided:</p>
1481<pre>import libxml2
1482log = ""
1483
1484class callback:
1485 def startDocument(self):
1486 global log
1487 log = log + "startDocument:"
1488
1489 def endDocument(self):
1490 global log
1491 log = log + "endDocument:"
1492
1493 def startElement(self, tag, attrs):
1494 global log
1495 log = log + "startElement %s %s:" % (tag, attrs)
1496
1497 def endElement(self, tag):
1498 global log
1499 log = log + "endElement %s:" % (tag)
1500
1501 def characters(self, data):
1502 global log
1503 log = log + "characters: %s:" % (data)
1504
1505 def warning(self, msg):
1506 global log
1507 log = log + "warning: %s:" % (msg)
1508
1509 def error(self, msg):
1510 global log
1511 log = log + "error: %s:" % (msg)
1512
1513 def fatalError(self, msg):
1514 global log
1515 log = log + "fatalError: %s:" % (msg)
1516
1517handler = callback()
1518
1519ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
1520chunk = " url='tst'&gt;b"
1521ctxt.parseChunk(chunk, len(chunk), 0)
1522chunk = "ar&lt;/foo&gt;"
1523ctxt.parseChunk(chunk, len(chunk), 1)
1524
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +00001525reference = "startDocument:startElement foo {'url': 'tst'}:" + \
1526 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001527if log != reference:
1528 print "Error got: %s" % log
1529 print "Exprected: %s" % reference</pre>
1530
1531<p>The key object in that test is the handler, it provides a number of entry
1532points which can be called by the parser as it makes progresses to indicate
1533the information set obtained. The full set of callback is larger than what
1534the callback class in that specific example implements (see the SAX
1535definition for a complete list). The wrapper will only call those supplied by
1536the object when activated. The startElement receives the names of the element
1537and a dictionnary containing the attributes carried by this element.</p>
1538
1539<p>Also note that the reference string generated from the callback shows a
1540single character call even though the string "bar" is passed to the parser
1541from 2 different call to parseChunk()</p>
1542
1543<h3>xpath.py:</h3>
1544
1545<p>This is a basic test of XPath warppers support</p>
1546<pre>import libxml2
1547
1548doc = libxml2.parseFile("tst.xml")
1549ctxt = doc.xpathNewContext()
1550res = ctxt.xpathEval("//*")
1551if len(res) != 2:
1552 print "xpath query: wrong node set size"
1553 sys.exit(1)
1554if res[0].name != "doc" or res[1].name != "foo":
1555 print "xpath query: wrong node set value"
1556 sys.exit(1)
1557doc.freeDoc()
1558ctxt.xpathFreeContext()</pre>
1559
1560<p>This test parses a file, then create an XPath context to evaluate XPath
1561expression on it. The xpathEval() method execute an XPath query and returns
1562the result mapped in a Python way. String and numbers are natively converted,
1563and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
1564the document, the XPath context need to be freed explicitely, also not that
1565the result of the XPath query may point back to the document tree and hence
1566the document must be freed after the result of the query is used.</p>
1567
1568<h3>xpathext.py:</h3>
1569
1570<p>This test shows how to extend the XPath engine with functions written in
1571python:</p>
1572<pre>import libxml2
1573
1574def foo(ctx, x):
1575 return x + 1
1576
1577doc = libxml2.parseFile("tst.xml")
1578ctxt = doc.xpathNewContext()
1579libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
1580res = ctxt.xpathEval("foo(1)")
1581if res != 2:
1582 print "xpath extension failure"
1583doc.freeDoc()
1584ctxt.xpathFreeContext()</pre>
1585
1586<p>Note how the extension function is registered with the context (but that
1587part is not yet finalized, ths may change slightly in the future).</p>
1588
1589<h3>tstxpath.py:</h3>
1590
1591<p>This test is similar to the previousone but shows how the extension
1592function can access the XPath evaluation context:</p>
1593<pre>def foo(ctx, x):
1594 global called
1595
1596 #
1597 # test that access to the XPath evaluation contexts
1598 #
1599 pctxt = libxml2.xpathParserContext(_obj=ctx)
1600 ctxt = pctxt.context()
1601 called = ctxt.function()
1602 return x + 1</pre>
1603
1604<p>All the interfaces around the XPath parser(or rather evaluation) context
1605are not finalized, but it should be sufficient to do contextual work at the
1606evaluation point.</p>
1607
1608<h3>Memory debugging:</h3>
1609
1610<p>last but not least, all tests starts with the following prologue:</p>
1611<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +00001612libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00001613
1614<p>and ends with the following epilogue:</p>
1615<pre>#memory debug specific
1616libxml2.cleanupParser()
1617if libxml2.debugMemory(1) == 0:
1618 print "OK"
1619else:
1620 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
1621 libxml2.dumpMemory()</pre>
1622
1623<p>Those activate the memory debugging interface of libxml2 where all
1624alloacted block in the library are tracked. The prologue then cleans up the
1625library state and checks that all allocated memory has been freed. If not it
1626calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
Daniel Veillard82687162001-01-22 15:32:01 +00001627
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00001628<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +00001629
Daniel Veillardec70e912001-02-26 20:10:45 +00001630<p>Libxml is made of multiple components; some of them are optional, and most
1631of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +00001632<ul>
1633 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +00001634 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +00001635 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +00001636 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +00001637 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +00001638 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +00001639 <li>a SAX tree module to build an in-memory DOM representation</li>
1640 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +00001641 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +00001642 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +00001643 (optional)</li>
1644 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +00001645</ul>
1646
1647<p>Graphically this gives the following:</p>
1648
1649<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1650
1651<p></p>
1652
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001653<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +00001654
1655<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +00001656returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001657<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +00001658as the file name, the document type, and a <strong>children</strong> pointer
1659which is the root of the document (or more exactly the first child under the
1660root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +00001661chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +00001662relationship. An xmlNode can also carry properties (a chain of xmlAttr
1663structures). An attribute may have a value which is a list of TEXT or
1664ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00001665
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001666<p>Here is an example (erroneous with respect to the XML spec since there
1667should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00001668
1669<p><img src="structure.gif" alt=" structure.gif "></p>
1670
1671<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +00001672called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001673prints them back as parsed. This is useful for detecting errors both in XML
1674code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +00001675which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00001676result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00001677<pre>DOCUMENT
1678version=1.0
1679standalone=true
1680 ELEMENT EXAMPLE
1681 ATTRIBUTE prop1
1682 TEXT
1683 content=gnome is great
1684 ATTRIBUTE prop2
1685 ENTITY_REF
1686 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +00001687 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +00001688 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00001689 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +00001690 TEXT
1691 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00001692 ELEMENT chapter
1693 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +00001694 TEXT
1695 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00001696 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +00001697 TEXT
1698 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00001699 ELEMENT image
1700 ATTRIBUTE href
1701 TEXT
1702 content=linus.gif
1703 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +00001704 TEXT
1705 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +00001706
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001707<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +00001708
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00001709<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001710
Daniel Veillard402e8c82000-02-29 22:57:47 +00001711<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001712memory. In that case (and if you don't expect to save back the XML document
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00001713loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1714a <strong>callback-based interface</strong> to the parser. Before parsing,
1715the application layer registers a customized set of callbacks which are
1716called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001717
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001718<p>To get more detailed step-by-step guidance on using the SAX interface of
Daniel Veillard4540be42000-08-19 16:40:28 +00001719libxml, see the <a
1720href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1721documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001722Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001723
1724<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1725program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001726binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +00001727distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +00001728testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001729<pre>SAX.setDocumentLocator()
1730SAX.startDocument()
1731SAX.getEntity(amp)
1732SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1733SAX.characters( , 3)
1734SAX.startElement(head)
1735SAX.characters( , 4)
1736SAX.startElement(title)
1737SAX.characters(Welcome to Gnome, 16)
1738SAX.endElement(title)
1739SAX.characters( , 3)
1740SAX.endElement(head)
1741SAX.characters( , 3)
1742SAX.startElement(chapter)
1743SAX.characters( , 4)
1744SAX.startElement(title)
1745SAX.characters(The Linux adventure, 19)
1746SAX.endElement(title)
1747SAX.characters( , 4)
1748SAX.startElement(p)
1749SAX.characters(bla bla bla ..., 15)
1750SAX.endElement(p)
1751SAX.characters( , 4)
1752SAX.startElement(image, href='linus.gif')
1753SAX.endElement(image)
1754SAX.characters( , 4)
1755SAX.startElement(p)
1756SAX.characters(..., 3)
1757SAX.endElement(p)
1758SAX.characters( , 3)
1759SAX.endElement(chapter)
1760SAX.characters( , 1)
1761SAX.endElement(EXAMPLE)
1762SAX.endDocument()</pre>
1763
Daniel Veillardec70e912001-02-26 20:10:45 +00001764<p>Most of the other interfaces of libxml are based on the DOM tree-building
1765facility, so nearly everything up to the end of this document presupposes the
1766use of the standard DOM tree build. Note that the DOM tree itself is built by
1767a set of registered default callbacks, without internal specific
1768interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00001769
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00001770<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1771
1772<p>Table of Content:</p>
1773<ol>
1774 <li><a href="#General5">General overview</a></li>
1775 <li><a href="#definition">The definition</a></li>
1776 <li><a href="#Simple">Simple rules</a>
1777 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +00001778 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00001779 <li><a href="#Declaring">Declaring elements</a></li>
1780 <li><a href="#Declaring1">Declaring attributes</a></li>
1781 </ol>
1782 </li>
1783 <li><a href="#Some">Some examples</a></li>
1784 <li><a href="#validate">How to validate</a></li>
1785 <li><a href="#Other">Other resources</a></li>
1786</ol>
1787
1788<h3><a name="General5">General overview</a></h3>
1789
1790<p>Well what is validation and what is a DTD ?</p>
1791
1792<p>DTD is the acronym for Document Type Definition. This is a description of
1793the content for a familly of XML files. This is part of the XML 1.0
1794specification, and alows to describe and check that a given document instance
1795conforms to a set of rules detailing its structure and content.</p>
1796
1797<p>Validation is the process of checking a document against a DTD (more
1798generally against a set of construction rules).</p>
1799
1800<p>The validation process and building DTDs are the two most difficult parts
1801of the XML life cycle. Briefly a DTD defines all the possibles element to be
1802found within your document, what is the formal shape of your document tree
1803(by defining the allowed content of an element, either text, a regular
1804expression for the allowed list of children, or mixed content i.e. both text
1805and children). The DTD also defines the allowed attributes for all elements
1806and the types of the attributes.</p>
1807
1808<h3><a name="definition1">The definition</a></h3>
1809
1810<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1811href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1812Rev1</a>):</p>
1813<ul>
1814 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1815 elements</a></li>
1816 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1817 attributes</a></li>
1818</ul>
1819
1820<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1821ancient...</p>
1822
1823<h3><a name="Simple1">Simple rules</a></h3>
1824
1825<p>Writing DTD can be done in multiple ways, the rules to build them if you
1826need something fixed or something which can evolve over time can be radically
1827different. Really complex DTD like Docbook ones are flexible but quite harder
1828to design. I will just focuse on DTDs for a formats with a fixed simple
1829structure. It is just a set of basic rules, and definitely not exhaustive nor
1830useable for complex DTD design.</p>
1831
1832<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1833
1834<p>Assuming the top element of the document is <code>spec</code> and the dtd
1835is placed in the file <code>mydtd</code> in the subdirectory
1836<code>dtds</code> of the directory from where the document were loaded:</p>
1837
1838<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1839
1840<p>Notes:</p>
1841<ul>
1842 <li>the system string is actually an URI-Reference (as defined in <a
1843 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1844 full URL string indicating the location of your DTD on the Web, this is a
1845 really good thing to do if you want others to validate your document</li>
1846 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1847 magic string) so that the DTd is looked up in catalogs on the client side
1848 without having to locate it on the web</li>
1849 <li>a dtd contains a set of elements and attributes declarations, but they
1850 don't define what the root of the document should be. This is explicitely
1851 told to the parser/validator as the first element of the
1852 <code>DOCTYPE</code> declaration.</li>
1853</ul>
1854
1855<h4><a name="Declaring2">Declaring elements</a>:</h4>
1856
1857<p>The following declares an element <code>spec</code>:</p>
1858
1859<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1860
1861<p>it also expresses that the spec element contains one <code>front</code>,
1862one <code>body</code> and one optionnal <code>back</code> children elements
1863in this order. The declaration of one element of the structure and its
1864content are done in a single declaration. Similary the following declares
1865<code>div1</code> elements:</p>
1866
Daniel Veillard51737272002-01-23 23:10:38 +00001867<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2?)&gt;</code></p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00001868
1869<p>means div1 contains one <code>head</code> then a series of optional
1870<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1871optional <code>div2</code>. And last but not least an element can contain
1872text:</p>
1873
1874<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1875
1876<p><code>b</code> contains text or being of mixed content (text and elements
1877in no particular order):</p>
1878
1879<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1880
1881<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1882<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1883order.</p>
1884
1885<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1886
1887<p>again the attributes declaration includes their content definition:</p>
1888
1889<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1890
1891<p>means that the element <code>termdef</code> can have a <code>name</code>
1892attribute containing text (<code>CDATA</code>) and which is optionnal
1893(<code>#IMPLIED</code>). The attribute value can also be defined within a
1894set:</p>
1895
1896<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1897"ordered"&gt;</code></p>
1898
1899<p>means <code>list</code> element have a <code>type</code> attribute with 3
1900allowed values "bullets", "ordered" or "glossary" and which default to
1901"ordered" if the attribute is not explicitely specified.</p>
1902
1903<p>The content type of an attribute can be text (<code>CDATA</code>),
1904anchor/reference/references
1905(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1906(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1907(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1908<code>chapter</code> element can have an optional <code>id</code> attribute
1909of type <code>ID</code>, usable for reference from attribute of type
1910IDREF:</p>
1911
1912<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1913
1914<p>The last value of an attribute definition can be <code>#REQUIRED
1915</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1916meaning that it is optional, or the default value (possibly prefixed by
1917<code>#FIXED</code> if it is the only allowed).</p>
1918
1919<p>Notes:</p>
1920<ul>
1921 <li>usually the attributes pertaining to a given element are declared in a
1922 single expression, but it is just a convention adopted by a lot of DTD
1923 writers:
1924 <pre>&lt;!ATTLIST termdef
1925 id ID #REQUIRED
1926 name CDATA #IMPLIED&gt;</pre>
1927 <p>The previous construct defines both <code>id</code> and
1928 <code>name</code> attributes for the element <code>termdef</code></p>
1929 </li>
1930</ul>
1931
1932<h3><a name="Some1">Some examples</a></h3>
1933
1934<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1935contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1936example shows an XML file where the simple DTD is directly included within
1937the document.</p>
1938
1939<h3><a name="validate1">How to validate</a></h3>
1940
1941<p>The simplest is to use the xmllint program comming with libxml. The
1942<code>--valid</code> option turn on validation of the files given as input,
1943for example the following validates a copy of the first revision of the XML
19441.0 specification:</p>
1945
1946<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1947
1948<p>the -- noout is used to not output the resulting tree.</p>
1949
1950<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1951a given DTD.</p>
1952
1953<p>Libxml exports an API to handle DTDs and validation, check the <a
1954href="http://xmlsoft.org/html/libxml-valid.html">associated
1955description</a>.</p>
1956
1957<h3><a name="Other1">Other resources</a></h3>
1958
1959<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1960will just list one for now, others pointers welcome:</p>
1961<ul>
1962 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1963</ul>
1964
1965<p>I suggest looking at the examples found under test/valid/dtd and any of
1966the large number of books available on XML. The dia example in test/valid
1967should be both simple and complete enough to allow you to build your own.</p>
1968
1969<p></p>
1970
1971<h2><a name="Memory">Memory Management</a></h2>
1972
1973<p>Table of Content:</p>
1974<ol>
1975 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +00001976 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00001977 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1978 <li><a href="#Debugging">Debugging routines</a></li>
1979 <li><a href="#General4">General memory requirements</a></li>
1980</ol>
1981
1982<h3><a name="General3">General overview</a></h3>
1983
1984<p>The module <code><a
1985href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1986provides the interfaces to the libxml memory system:</p>
1987<ul>
1988 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1989 xmlMalloc() and xmlRealloc()</li>
1990 <li>those routines can be reallocated to a specific set of routine, by
1991 default the libc ones i.e. free(), malloc() and realloc()</li>
1992 <li>the xmlmemory.c module includes a set of debugging routine</li>
1993</ul>
1994
1995<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1996
1997<p>It is sometimes useful to not use the default memory allocator, either for
1998debugging, analysis or to implement a specific behaviour on memory management
1999(like on embedded systems). Two function calls are available to do so:</p>
2000<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +00002001 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet
2002 ()</a> which return the current set of functions in use by the parser</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002003 <li><a
2004 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
Daniel Veillardaf43f632002-03-08 15:05:20 +00002005 which allow to set up a new set of memory allocation functions</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002006</ul>
2007
2008<p>Of course a call to xmlMemSetup() should probably be done before calling
2009any other libxml routines (unless you are sure your allocations routines are
2010compatibles).</p>
2011
2012<h3><a name="cleanup">Cleaning up after parsing</a></h3>
2013
2014<p>Libxml is not stateless, there is a few set of memory structures needing
2015allocation before the parser is fully functionnal (some encoding structures
2016for example). This also mean that once parsing is finished there is a tiny
2017amount of memory (a few hundred bytes) which can be recollected if you don't
2018reuse the parser immediately:</p>
2019<ul>
2020 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
Daniel Veillardaf43f632002-03-08 15:05:20 +00002021 ()</a> is a centralized routine to free the parsing states. Note that it
2022 won't deallocate any produced tree if any (use the xmlFreeDoc() and
2023 related routines for this).</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002024 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
Daniel Veillardaf43f632002-03-08 15:05:20 +00002025 ()</a> is the dual routine allowing to preallocate the parsing state
2026 which can be useful for example to avoid initialization reentrancy
2027 problems when using libxml in multithreaded applications</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002028</ul>
2029
2030<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
2031at the next invocation of parser routines, but be careful of the consequences
2032in multithreaded applications.</p>
2033
2034<h3><a name="Debugging">Debugging routines</a></h3>
2035
2036<p>When configured using --with-mem-debug flag (off by default), libxml uses
2037a set of memory allocation debugging routineskeeping track of all allocated
2038blocks and the location in the code where the routine was called. A couple of
2039other debugging routines allow to dump the memory allocated infos to a file
2040or call a specific routine when a given block number is allocated:</p>
2041<ul>
2042 <li><a
2043 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
Daniel Veillardaf43f632002-03-08 15:05:20 +00002044 <a
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002045 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
2046 and <a
2047 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
2048 are the memory debugging replacement allocation routines</li>
2049 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
Daniel Veillardaf43f632002-03-08 15:05:20 +00002050 ()</a> dumps all the informations about the allocated memory block lefts
2051 in the <code>.memdump</code> file</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002052</ul>
2053
2054<p>When developping libxml memory debug is enabled, the tests programs call
2055xmlMemoryDump () and the "make test" regression tests will check for any
2056memory leak during the full regression test sequence, this helps a lot
2057ensuring that libxml does not leak memory and bullet proof memory
2058allocations use (some libc implementations are known to be far too permissive
2059resulting in major portability problems!).</p>
2060
2061<p>If the .memdump reports a leak, it displays the allocation function and
2062also tries to give some informations about the content and structure of the
2063allocated blocks left. This is sufficient in most cases to find the culprit,
2064but not always. Assuming the allocation problem is reproductible, it is
2065possible to find more easilly:</p>
2066<ol>
2067 <li>write down the block number xxxx not allocated</li>
2068 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
2069 <li>run the program under a debugger and set a breakpoint on
2070 xmlMallocBreakpoint() a specific function called when this precise block
2071 is allocated</li>
2072 <li>when the breakpoint is reached you can then do a fine analysis of the
2073 allocation an step to see the condition resulting in the missing
2074 deallocation.</li>
2075</ol>
2076
2077<p>I used to use a commercial tool to debug libxml memory problems but after
2078noticing that it was not detecting memory leaks that simple mechanism was
2079used and proved extremely efficient until now.</p>
2080
2081<h3><a name="General4">General memory requirements</a></h3>
2082
2083<p>How much libxml memory require ? It's hard to tell in average it depends
2084of a number of things:</p>
2085<ul>
2086 <li>the parser itself should work in a fixed amout of memory, except for
2087 information maintained about the stacks of names and entities locations.
2088 The I/O and encoding handlers will probably account for a few KBytes.
2089 This is true for both the XML and HTML parser (though the HTML parser
2090 need more state).</li>
2091 <li>If you are generating the DOM tree then memory requirements will grow
2092 nearly lineary with the size of the data. In general for a balanced
2093 textual document the internal memory requirement is about 4 times the
2094 size of the UTF8 serialization of this document (exmple the XML-1.0
2095 recommendation is a bit more of 150KBytes and takes 650KBytes of main
2096 memory when parsed). Validation will add a amount of memory required for
2097 maintaining the external Dtd state which should be linear with the
2098 complexity of the content model defined by the Dtd</li>
2099 <li>If you don't care about the advanced features of libxml like
2100 validation, DOM, XPath or XPointer, but really need to work fixed memory
2101 requirements, then the SAX interface should be used.</li>
2102</ul>
2103
2104<p></p>
2105
2106<h2><a name="Encodings">Encodings support</a></h2>
2107
2108<p>Table of Content:</p>
2109<ol>
2110 <li><a href="encoding.html#What">What does internationalization support
2111 mean ?</a></li>
2112 <li><a href="encoding.html#internal">The internal encoding, how and
2113 why</a></li>
2114 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
2115 <li><a href="encoding.html#Default">Default supported encodings</a></li>
2116 <li><a href="encoding.html#extend">How to extend the existing
2117 support</a></li>
2118</ol>
2119
2120<h3><a name="What">What does internationalization support mean ?</a></h3>
2121
2122<p>XML was designed from the start to allow the support of any character set
2123by using Unicode. Any conformant XML parser has to support the UTF-8 and
2124UTF-16 default encodings which can both express the full unicode ranges. UTF8
2125is a variable length encoding whose greatest point are to resuse the same
2126emcoding for ASCII and to save space for Western encodings, but it is a bit
2127more complex to handle in practice. UTF-16 use 2 bytes per characters (and
2128sometimes combines two pairs), it makes implementation easier, but looks a
2129bit overkill for Western languages encoding. Moreover the XML specification
2130allows document to be encoded in other encodings at the condition that they
2131are clearly labelled as such. For example the following is a wellformed XML
2132document encoded in ISO-8859 1 and using accentuated letter that we French
2133likes for both markup and content:</p>
2134<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2135&lt;très&gt;là&lt;/très&gt;</pre>
2136
2137<p>Having internationalization support in libxml means the foolowing:</p>
2138<ul>
2139 <li>the document is properly parsed</li>
2140 <li>informations about it's encoding are saved</li>
2141 <li>it can be modified</li>
2142 <li>it can be saved in its original encoding</li>
2143 <li>it can also be saved in another encoding supported by libxml (for
2144 example straight UTF8 or even an ASCII form)</li>
2145</ul>
2146
2147<p>Another very important point is that the whole libxml API, with the
2148exception of a few routines to read with a specific encoding or save to a
2149specific encoding, is completely agnostic about the original encoding of the
2150document.</p>
2151
2152<p>It should be noted too that the HTML parser embedded in libxml now obbey
2153the same rules too, the following document will be (as of 2.2.2) handled in
2154an internationalized fashion by libxml too:</p>
2155<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
2156 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
2157&lt;html lang="fr"&gt;
2158&lt;head&gt;
2159 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
2160&lt;/head&gt;
2161&lt;body&gt;
2162&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
2163&lt;/html&gt;</pre>
2164
2165<h3><a name="internal">The internal encoding, how and why</a></h3>
2166
2167<p>One of the core decision was to force all documents to be converted to a
2168default internal encoding, and that encoding to be UTF-8, here are the
2169rationale for those choices:</p>
2170<ul>
2171 <li>keeping the native encoding in the internal form would force the libxml
2172 users (or the code associated) to be fully aware of the encoding of the
2173 original document, for examples when adding a text node to a document,
2174 the content would have to be provided in the document encoding, i.e. the
2175 client code would have to check it before hand, make sure it's conformant
2176 to the encoding, etc ... Very hard in practice, though in some specific
2177 cases this may make sense.</li>
2178 <li>the second decision was which encoding. From the XML spec only UTF8 and
2179 UTF16 really makes sense as being the two only encodings for which there
2180 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
2181 considered an intelligent choice too since it's a direct Unicode mapping
2182 support. I selected UTF-8 on the basis of efficiency and compatibility
2183 with surrounding software:
2184 <ul>
2185 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
2186 more costly to import and export CPU wise) is also far more compact
2187 than UTF-16 (and UCS-4) for a majority of the documents I see it used
2188 for right now (RPM RDF catalogs, advogato data, various configuration
2189 file formats, etc.) and the key point for today's computer
2190 architecture is efficient uses of caches. If one nearly double the
2191 memory requirement to store the same amount of data, this will trash
2192 caches (main memory/external caches/internal caches) and my take is
2193 that this harms the system far more than the CPU requirements needed
2194 for the conversion to UTF-8</li>
2195 <li>Most of libxml version 1 users were using it with straight ASCII
2196 most of the time, doing the conversion with an internal encoding
2197 requiring all their code to be rewritten was a serious show-stopper
2198 for using UTF-16 or UCS-4.</li>
2199 <li>UTF-8 is being used as the de-facto internal encoding standard for
2200 related code like the <a href="http://www.pango.org/">pango</a>
2201 upcoming Gnome text widget, and a lot of Unix code (yep another place
2202 where Unix programmer base takes a different approach from Microsoft
2203 - they are using UTF-16)</li>
2204 </ul>
2205 </li>
2206</ul>
2207
2208<p>What does this mean in practice for the libxml user:</p>
2209<ul>
2210 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
2211 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
2212 is simply to append 0 byte, as usual.</li>
2213 <li>One just need to make sure that when using chars outside the ASCII set,
2214 the values has been properly converted to UTF-8</li>
2215</ul>
2216
2217<h3><a name="implemente">How is it implemented ?</a></h3>
2218
2219<p>Let's describe how all this works within libxml, basically the I18N
2220(internationalization) support get triggered only during I/O operation, i.e.
2221when reading a document or saving one. Let's look first at the reading
2222sequence:</p>
2223<ol>
2224 <li>when a document is processed, we usually don't know the encoding, a
2225 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
2226 ASCII range (0-0x7F) maps with ASCII</li>
2227 <li>the xml declaration if available is parsed, including the encoding
2228 declaration. At that point, if the autodetected encoding is different
2229 from the one declared a call to xmlSwitchEncoding() is issued.</li>
2230 <li>If there is no encoding declaration, then the input has to be in either
2231 UTF-8 or UTF-16, if it is not then at some point when processing the
2232 input, the converter/checker of UTF-8 form will raise an encoding error.
2233 You may end-up with a garbled document, or no document at all ! Example:
2234 <pre>~/XML -&gt; ./xmllint err.xml
2235err.xml:1: error: Input is not proper UTF-8, indicate encoding !
2236&lt;très&gt;là&lt;/très&gt;
2237 ^
2238err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
2239&lt;très&gt;là&lt;/très&gt;
2240 ^</pre>
2241 </li>
2242 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
2243 then search the default registered encoding converters for that encoding.
2244 If it's not within the default set and iconv() support has been compiled
2245 it, it will ask iconv for such an encoder. If this fails then the parser
2246 will report an error and stops processing:
2247 <pre>~/XML -&gt; ./xmllint err2.xml
2248err2.xml:1: error: Unsupported encoding UnsupportedEnc
2249&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
2250 ^</pre>
2251 </li>
2252 <li>From that point the encoder process progressingly the input (it is
2253 plugged as a front-end to the I/O module) for that entity. It captures
2254 and convert on-the-fly the document to be parsed to UTF-8. The parser
2255 itself just does UTF-8 checking of this input and process it
2256 transparently. The only difference is that the encoding information has
2257 been added to the parsing context (more precisely to the input
2258 corresponding to this entity).</li>
2259 <li>The result (when using DOM) is an internal form completely in UTF-8
2260 with just an encoding information on the document node.</li>
2261</ol>
2262
2263<p>Ok then what's happen when saving the document (assuming you
2264colllected/built an xmlDoc DOM like structure) ? It depends on the function
2265called, xmlSaveFile() will just try to save in the original encoding, while
2266xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
2267encoding:</p>
2268<ol>
2269 <li>if no encoding is given, libxml will look for an encoding value
2270 associated to the document and if it exists will try to save to that
2271 encoding,
2272 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
2273 </li>
2274 <li>so if an encoding was specified, either at the API level or on the
2275 document, libxml will again canonalize the encoding name, lookup for a
2276 converter in the registered set or through iconv. If not found the
2277 function will return an error code</li>
2278 <li>the converter is placed before the I/O buffer layer, as another kind of
2279 buffer, then libxml will simply push the UTF-8 serialization to through
2280 that buffer, which will then progressively be converted and pushed onto
2281 the I/O layer.</li>
2282 <li>It is possible that the converter code fails on some input, for example
2283 trying to push an UTF-8 encoded chinese character through the UTF-8 to
2284 ISO-8859-1 converter won't work. Since the encoders are progressive they
2285 will just report the error and the number of bytes converted, at that
2286 point libxml will decode the offending character, remove it from the
2287 buffer and replace it with the associated charRef encoding &amp;#123; and
2288 resume the convertion. This guarante that any document will be saved
2289 without losses (except for markup names where this is not legal, this is
2290 a problem in the current version, in pactice avoid using non-ascci
2291 characters for tags or attributes names @@). A special "ascii" encoding
2292 name is used to save documents to a pure ascii form can be used when
2293 portability is really crucial</li>
2294</ol>
2295
2296<p>Here is a few examples based on the same test document:</p>
2297<pre>~/XML -&gt; ./xmllint isolat1
2298&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2299&lt;très&gt;là&lt;/très&gt;
2300~/XML -&gt; ./xmllint --encode UTF-8 isolat1
2301&lt;?xml version="1.0" encoding="UTF-8"?&gt;
2302&lt;très&gt;là  &lt;/très&gt;
2303~/XML -&gt; </pre>
2304
2305<p>The same processing is applied (and reuse most of the code) for HTML I18N
2306processing. Looking up and modifying the content encoding is a bit more
2307difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
2308so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
2309been provided. The parser also attempts to switch encoding on the fly when
2310detecting such a tag on input. Except for that the processing is the same
2311(and again reuses the same code).</p>
2312
2313<h3><a name="Default">Default supported encodings</a></h3>
2314
2315<p>libxml has a set of default converters for the following encodings
2316(located in encoding.c):</p>
2317<ol>
2318 <li>UTF-8 is supported by default (null handlers)</li>
2319 <li>UTF-16, both little and big endian</li>
2320 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
2321 <li>ASCII, useful mostly for saving</li>
2322 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
2323 predefined entities like &amp;copy; for the Copyright sign.</li>
2324</ol>
2325
2326<p>More over when compiled on an Unix platfor with iconv support the full set
2327of encodings supported by iconv can be instantly be used by libxml. On a
2328linux machine with glibc-2.1 the list of supported encodings and aliases fill
23293 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
2330various Japanese ones.</p>
2331
2332<h4>Encoding aliases</h4>
2333
2334<p>From 2.2.3, libxml has support to register encoding names aliases. The
2335goal is to be able to parse document whose encoding is supported but where
2336the name differs (for example from the default set of names accepted by
2337iconv). The following functions allow to register and handle new aliases for
2338existing encodings. Once registered libxml will automatically lookup the
2339aliases when handling a document:</p>
2340<ul>
2341 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
2342 <li>int xmlDelEncodingAlias(const char *alias);</li>
2343 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
2344 <li>void xmlCleanupEncodingAliases(void);</li>
2345</ul>
2346
2347<h3><a name="extend">How to extend the existing support</a></h3>
2348
2349<p>Well adding support for new encoding, or overriding one of the encoders
2350(assuming it is buggy) should not be hard, just write an input and output
2351conversion routines to/from UTF-8, and register them using
2352xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
2353called automatically if the parser(s) encounter such an encoding name
2354(register it uppercase, this will help). The description of the encoders,
2355their arguments and expected return values are described in the encoding.h
2356header.</p>
2357
2358<p>A quick note on the topic of subverting the parser to use a different
2359internal encoding than UTF-8, in some case people will absolutely want to
2360keep the internal encoding different, I think it's still possible (but the
2361encoding must be compliant with ASCII on the same subrange) though I didn't
2362tried it. The key is to override the default conversion routines (by
2363registering null encoders/decoders for your charsets), and bypass the UTF-8
2364checking of the parser by setting the parser context charset
2365(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2366there is no guarantee taht this will work. You may also have some troubles
2367saving back.</p>
2368
2369<p>Basically proper I18N support is important, this requires at least
2370libxml-2.0.0, but a lot of features and corrections are really available only
2371starting 2.2.</p>
2372
2373<h2><a name="IO">I/O Interfaces</a></h2>
2374
2375<p>Table of Content:</p>
2376<ol>
2377 <li><a href="#General1">General overview</a></li>
2378 <li><a href="#basic">The basic buffer type</a></li>
2379 <li><a href="#Input">Input I/O handlers</a></li>
2380 <li><a href="#Output">Output I/O handlers</a></li>
2381 <li><a href="#entities">The entities loader</a></li>
2382 <li><a href="#Example2">Example of customized I/O</a></li>
2383</ol>
2384
2385<h3><a name="General1">General overview</a></h3>
2386
2387<p>The module <code><a
2388href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2389the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2390<ul>
2391 <li>Entities loader, this is a routine which tries to fetch the entities
2392 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2393 don't look at the public identifier since libxml do not maintain a
2394 catalog. You can redefine you own entity loader by using
2395 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +00002396 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2397 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002398 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2399 input layer to handle fetching the informations to feed the parser. This
2400 provides buffering and is also a placeholder where the encoding
2401 convertors to UTF8 are piggy-backed.</li>
2402 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2403 task but when generating a serialization from a tree.</li>
2404 <li>A mechanism to register sets of I/O callbacks and associate them with
2405 specific naming schemes like the protocol part of the URIs.
2406 <p>This affect the default I/O operations and allows to use specific I/O
2407 handlers for certain names.</p>
2408 </li>
2409</ul>
2410
2411<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2412example in the HTML parser is the following:</p>
2413<ol>
2414 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2415 the parsing context and the URI string.</li>
2416 <li>the URI string is checked against the existing registered handlers
2417 using their match() callback function, if the HTTP module was compiled
2418 in, it is registered and its match() function will succeeds</li>
2419 <li>the open() function of the handler is called and if successful will
2420 return an I/O Input buffer</li>
2421 <li>the parser will the start reading from this buffer and progressively
2422 fetch information from the resource, calling the read() function of the
2423 handler until the resource is exhausted</li>
2424 <li>if an encoding change is detected it will be installed on the input
2425 buffer, providing buffering and efficient use of the conversion
2426 routines</li>
2427 <li>once the parser has finished, the close() function of the handler is
2428 called once and the Input buffer and associed resources are
2429 deallocated.</li>
2430</ol>
2431
2432<p>The user defined callbacks are checked first to allow overriding of the
2433default libxml I/O routines.</p>
2434
2435<h3><a name="basic">The basic buffer type</a></h3>
2436
2437<p>All the buffer manipulation handling is done using the
2438<code>xmlBuffer</code> type define in <code><a
2439href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2440resizable memory buffer. The buffer allocation strategy can be selected to be
2441either best-fit or use an exponential doubling one (CPU vs. memory use
2442tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2443<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2444system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2445of functions allows to manipulate buffers with names starting with the
2446<code>xmlBuffer...</code> prefix.</p>
2447
2448<h3><a name="Input">Input I/O handlers</a></h3>
2449
2450<p>An Input I/O handler is a simple structure
2451<code>xmlParserInputBuffer</code> containing a context associated to the
2452resource (file descriptor, or pointer to a protocol handler), the read() and
2453close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2454encoding handler are also present to support charset conversion when
2455needed.</p>
2456
2457<h3><a name="Output">Output I/O handlers</a></h3>
2458
2459<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2460Input one except the callbacks are write() and close().</p>
2461
2462<h3><a name="entities">The entities loader</a></h3>
2463
2464<p>The entity loader resolves requests for new entities and create inputs for
2465the parser. Creating an input from a filename or an URI string is done
2466through the xmlNewInputFromFile() routine. The default entity loader do not
2467handle the PUBLIC identifier associated with an entity (if any). So it just
2468calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2469XML).</p>
2470
2471<p>If you want to hook up a catalog mechanism then you simply need to
2472override the default entity loader, here is an example:</p>
2473<pre>#include &lt;libxml/xmlIO.h&gt;
2474
2475xmlExternalEntityLoader defaultLoader = NULL;
2476
2477xmlParserInputPtr
2478xmlMyExternalEntityLoader(const char *URL, const char *ID,
2479 xmlParserCtxtPtr ctxt) {
2480 xmlParserInputPtr ret;
2481 const char *fileID = NULL;
2482 /* lookup for the fileID depending on ID */
2483
2484 ret = xmlNewInputFromFile(ctxt, fileID);
2485 if (ret != NULL)
2486 return(ret);
2487 if (defaultLoader != NULL)
2488 ret = defaultLoader(URL, ID, ctxt);
2489 return(ret);
2490}
2491
2492int main(..) {
2493 ...
2494
2495 /*
2496 * Install our own entity loader
2497 */
2498 defaultLoader = xmlGetExternalEntityLoader();
2499 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2500
2501 ...
2502}</pre>
2503
2504<h3><a name="Example2">Example of customized I/O</a></h3>
2505
2506<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2507real use case</a>, xmlDocDump() closes the FILE * passed by the application
2508and this was a problem. The <a
2509href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2510new output handler with the closing call deactivated:</p>
2511<ol>
2512 <li>First define a new I/O ouput allocator where the output don't close the
2513 file:
2514 <pre>xmlOutputBufferPtr
2515xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2516    xmlOutputBufferPtr ret;
2517    
2518    if (xmlOutputCallbackInitialized == 0)
2519        xmlRegisterDefaultOutputCallbacks();
2520
2521    if (file == NULL) return(NULL);
2522    ret = xmlAllocOutputBuffer(encoder);
2523    if (ret != NULL) {
2524        ret-&gt;context = file;
2525        ret-&gt;writecallback = xmlFileWrite;
2526        ret-&gt;closecallback = NULL; /* No close callback */
2527    }
2528    return(ret); <br>
2529
2530
2531
Daniel Veillard9c466822001-10-25 12:03:39 +00002532
2533
Daniel Veillardc6271d22001-10-27 07:50:58 +00002534
Daniel Veillard51095312001-10-28 18:51:57 +00002535
Daniel Veillard52dcab32001-10-30 12:51:17 +00002536
Daniel Veillarded421aa2001-11-04 21:22:45 +00002537
Daniel Veillard43d3f612001-11-10 11:57:23 +00002538
Daniel Veillarda4871052001-11-26 13:19:48 +00002539
Daniel Veillard1aadc442001-11-28 13:10:32 +00002540
Daniel Veillardef90ba72001-12-07 14:24:22 +00002541
Daniel Veillard9ae4b7a2001-12-13 14:24:09 +00002542
Daniel Veillard845cce42002-01-09 11:51:37 +00002543
Daniel Veillard744683d2002-01-14 17:30:20 +00002544
Daniel Veillard35e937a2002-01-19 22:21:54 +00002545
Daniel Veillardc575b992002-02-08 13:28:40 +00002546
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +00002547
Daniel Veillard397ff112002-02-11 18:27:20 +00002548
Daniel Veillarde46182c2002-02-12 14:29:11 +00002549
Daniel Veillard5f4b5992002-02-20 10:22:49 +00002550
Daniel Veillard5b16f582002-02-20 11:38:46 +00002551
Daniel Veillarda5393562002-02-20 11:40:49 +00002552
Daniel Veillard6dbcaf82002-02-20 14:37:47 +00002553
2554
2555
Daniel Veillardaf43f632002-03-08 15:05:20 +00002556
Daniel Veillard5c396542002-03-15 07:57:50 +00002557
Daniel Veillard2d347fa2002-03-17 10:34:11 +00002558
2559
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002560} </pre>
2561 </li>
2562 <li>And then use it to save the document:
2563 <pre>FILE *f;
2564xmlOutputBufferPtr output;
2565xmlDocPtr doc;
2566int res;
2567
2568f = ...
2569doc = ....
2570
2571output = xmlOutputBufferCreateOwn(f, NULL);
2572res = xmlSaveFileTo(output, doc, NULL);
2573 </pre>
2574 </li>
2575</ol>
2576
2577<h2><a name="Catalog">Catalog support</a></h2>
2578
2579<p>Table of Content:</p>
2580<ol>
2581 <li><a href="General2">General overview</a></li>
2582 <li><a href="#definition">The definition</a></li>
2583 <li><a href="#Simple">Using catalogs</a></li>
2584 <li><a href="#Some">Some examples</a></li>
2585 <li><a href="#reference">How to tune catalog usage</a></li>
2586 <li><a href="#validate">How to debug catalog processing</a></li>
2587 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2588 <li><a href="#implemento">The implementor corner quick review of the
2589 API</a></li>
2590 <li><a href="#Other">Other resources</a></li>
2591</ol>
2592
2593<h3><a name="General2">General overview</a></h3>
2594
2595<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2596(a file or a remote resource) references another entity. The catalog lookup
2597is inserted between the moment the reference is recognized by the software
2598(XML parser, stylesheet processing, or even images referenced for inclusion
2599in a rendering) and the time where loading that resource is actually
2600started.</p>
2601
2602<p>It is basically used for 3 things:</p>
2603<ul>
2604 <li>mapping from "logical" names, the public identifiers and a more
2605 concrete name usable for download (and URI). For example it can associate
2606 the logical name
2607 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2608 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2609 downloaded</p>
2610 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2611 </li>
2612 <li>remapping from a given URL to another one, like an HTTP indirection
2613 saying that
2614 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2615 <p>should really be looked at</p>
2616 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2617 </li>
2618 <li>providing a local cache mechanism allowing to load the entities
2619 associated to public identifiers or remote resources, this is a really
2620 important feature for any significant deployment of XML or SGML since it
2621 allows to avoid the aleas and delays associated to fetching remote
2622 resources.</li>
2623</ul>
2624
2625<h3><a name="definition">The definitions</a></h3>
2626
2627<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2628<ul>
2629 <li>the older SGML catalogs, the official spec is SGML Open Technical
2630 Resolution TR9401:1997, but is better understood by reading <a
2631 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2632 James Clark. This is relatively old and not the preferred mode of
2633 operation of libxml.</li>
2634 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
Daniel Veillardaf43f632002-03-08 15:05:20 +00002635 Catalogs</a> is far more flexible, more recent, uses an XML syntax and
2636 should scale quite better. This is the default option of libxml.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002637</ul>
2638
2639<p></p>
2640
2641<h3><a name="Simple">Using catalog</a></h3>
2642
2643<p>In a normal environment libxml will by default check the presence of a
2644catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2645the processing is completely transparent to the document user. To take a
2646concrete example, suppose you are authoring a DocBook document, this one
2647starts with the following DOCTYPE definition:</p>
2648<pre>&lt;?xml version='1.0'?&gt;
2649&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2650 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2651
2652<p>When validating the document with libxml, the catalog will be
2653automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2654DocBk XML V3.1.4//EN" and the system identifier
2655"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2656been installed on your system and the catalogs actually point to them, libxml
2657will fetch them from the local disk.</p>
2658
2659<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2660DOCTYPE example it's a really old version, but is fine as an example.</p>
2661
2662<p>Libxml will check the catalog each time that it is requested to load an
2663entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2664your system is correctly configured all the authoring phase and processing
2665should use only local files, even if your document stays portable because it
2666uses the canonical public and system ID, referencing the remote document.</p>
2667
2668<h3><a name="Some">Some examples:</a></h3>
2669
2670<p>Here is a couple of fragments from XML Catalogs used in libxml early
2671regression tests in <code>test/catalogs</code> :</p>
2672<pre>&lt;?xml version="1.0"?&gt;
2673&lt;!DOCTYPE catalog PUBLIC
2674 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2675 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2676&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2677 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2678 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2679...</pre>
2680
2681<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2682written in XML, there is a specific namespace for catalog elements
2683"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2684catalog is a <code>public</code> mapping it allows to associate a Public
2685Identifier with an URI.</p>
2686<pre>...
2687 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2688 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2689...</pre>
2690
2691<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2692any URI starting with a given prefix should be looked at another URI
2693constructed by replacing the prefix with an new one. In effect this acts like
2694a cache system for a full area of the Web. In practice it is extremely useful
2695with a file prefix if you have installed a copy of those resources on your
2696local system.</p>
2697<pre>...
2698&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2699 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2700&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2701 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2702&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2703 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2704&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2705 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2706&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2707 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2708...</pre>
2709
2710<p>Delegation is the core features which allows to build a tree of catalogs,
2711easier to maintain than a single catalog, based on Public Identifier, System
2712Identifier or URI prefixes it instructs the catalog software to look up
2713entries in another resource. This feature allow to build hierarchies of
2714catalogs, the set of entries presented should be sufficient to redirect the
2715resolution of all DocBook references to the specific catalog in
2716<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2717references for DocBook 4.2.1 to a specific catalog installed at the same time
2718as the DocBook resources on the local machine.</p>
2719
2720<h3><a name="reference">How to tune catalog usage:</a></h3>
2721
2722<p>The user can change the default catalog behaviour by redirecting queries
2723to its own set of catalogs, this can be done by setting the
2724<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2725empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2726default catalog</p>
2727
2728<h3><a name="validate">How to debug catalog processing:</a></h3>
2729
2730<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2731make libxml output debugging informations for each catalog operations, for
2732example:</p>
2733<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2734warning: failed to load external entity "title.xml"
2735orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2736orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2737Failed to parse catalog /etc/xml/catalog
2738Failed to parse catalog /etc/xml/catalog
2739warning: failed to load external entity "title.xml"
2740Catalogs cleanup
2741orchis:~/XML -&gt; </pre>
2742
2743<p>The test/ent2 references an entity, running the parser from memory makes
2744the base URI unavailable and the the "title.xml" entity cannot be loaded.
2745Setting up the debug environment variable allows to detect that an attempt is
2746made to load the <code>/etc/xml/catalog</code> but since it's not present the
2747resolution fails.</p>
2748
2749<p>But the most advanced way to debug XML catalog processing is to use the
2750<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2751catalogs and make resolution queries to see what is going on. This is also
2752used for the regression tests:</p>
2753<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2754 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2755http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2756orchis:~/XML -&gt; </pre>
2757
2758<p>For debugging what is going on, adding one -v flags increase the verbosity
2759level to indicate the processing done (adding a second flag also indicate
2760what elements are recognized at parsing):</p>
2761<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2762 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2763Parsing catalog test/catalogs/docbook.xml's content
2764Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2765http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2766Catalogs cleanup
2767orchis:~/XML -&gt; </pre>
2768
2769<p>A shell interface is also available to debug and process multiple queries
2770(and for regression tests):</p>
2771<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2772 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2773&gt; help
2774Commands available:
2775public PublicID: make a PUBLIC identifier lookup
2776system SystemID: make a SYSTEM identifier lookup
2777resolve PublicID SystemID: do a full resolver lookup
2778add 'type' 'orig' 'replace' : add an entry
2779del 'values' : remove values
2780dump: print the current catalog state
2781debug: increase the verbosity level
2782quiet: decrease the verbosity level
2783exit: quit the shell
2784&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2785http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2786&gt; quit
2787orchis:~/XML -&gt; </pre>
2788
2789<p>This should be sufficient for most debugging purpose, this was actually
2790used heavily to debug the XML Catalog implementation itself.</p>
2791
2792<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2793
2794<p>Basically XML Catalogs are XML files, you can either use XML tools to
2795manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2796to create a catalog the -create option provide this facility:</p>
2797<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2798&lt;?xml version="1.0"?&gt;
2799&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2800 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2801&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2802orchis:~/XML -&gt; </pre>
2803
2804<p>By default xmlcatalog does not overwrite the original catalog and save the
2805result on the standard output, this can be overridden using the -noout
2806option. The <code>-add</code> command allows to add entries in the
2807catalog:</p>
2808<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2809 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2810 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2811orchis:~/XML -&gt; cat tst.xml
2812&lt;?xml version="1.0"?&gt;
2813&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2814 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2815&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2816&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2817 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2818&lt;/catalog&gt;
2819orchis:~/XML -&gt; </pre>
2820
2821<p>The <code>-add</code> option will always take 3 parameters even if some of
2822the XML Catalog constructs (like nextCatalog) will have only a single
2823argument, just pass a third empty string, it will be ignored.</p>
2824
2825<p>Similarly the <code>-del</code> option remove matching entries from the
2826catalog:</p>
2827<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2828 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2829&lt;?xml version="1.0"?&gt;
2830&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2831 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2832&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2833orchis:~/XML -&gt; </pre>
2834
2835<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2836exact and would have worked in a similar fashion with the Public ID
2837string.</p>
2838
2839<p>This is rudimentary but should be sufficient to manage a not too complex
2840catalog tree of resources.</p>
2841
2842<h3><a name="implemento">The implementor corner quick review of the
2843API:</a></h3>
2844
2845<p>First, and like for every other module of libxml, there is an
2846automatically generated <a href="html/libxml-catalog.html">API page for
2847catalog support</a>.</p>
2848
2849<p>The header for the catalog interfaces should be included as:</p>
2850<pre>#include &lt;libxml/catalog.h&gt;</pre>
2851
2852<p>The API is voluntarily kept very simple. First it is not obvious that
2853applications really need access to it since it is the default behaviour of
2854libxml (Note: it is possible to completely override libxml default catalog by
2855using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2856plug an application specific resolver).</p>
2857
2858<p>Basically libxml support 2 catalog lists:</p>
2859<ul>
2860 <li>the default one, global shared by all the application</li>
2861 <li>a per-document catalog, this one is built if the document uses the
2862 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2863 associated to the parser context and destroyed when the parsing context
2864 is destroyed.</li>
2865</ul>
2866
2867<p>the document one will be used first if it exists.</p>
2868
2869<h4>Initialization routines:</h4>
2870
2871<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2872used at startup to initialize the catalog, if the catalog should be
2873initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2874should be called before xmlInitializeCatalog() which would otherwise do a
2875default initialization first.</p>
2876
2877<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2878own catalog list if needed.</p>
2879
2880<h4>Preferences setup:</h4>
2881
2882<p>The XML Catalog spec requires the possibility to select default
2883preferences between public and system delegation,
2884xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2885xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2886be forbidden, allowed for global catalog, for document catalog or both, the
2887default is to allow both.</p>
2888
2889<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2890(through the xmlGenericError() mechanism).</p>
2891
2892<h4>Querying routines:</h4>
2893
2894<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2895and xmlCatalogResolveURI() are relatively explicit if you read the XML
2896Catalog specification they correspond to section 7 algorithms, they should
2897also work if you have loaded an SGML catalog with a simplified semantic.</p>
2898
2899<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2900operate on the document catalog list</p>
2901
2902<h4>Cleanup and Miscellaneous:</h4>
2903
2904<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2905the per-document equivalent.</p>
2906
2907<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2908first catalog in the global list, and xmlCatalogDump() allows to dump a
2909catalog state, those routines are primarily designed for xmlcatalog, I'm not
2910sure that exposing more complex interfaces (like navigation ones) would be
2911really useful.</p>
2912
2913<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2914it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2915provided because this functionality may be useful for client tools.</p>
2916
2917<h4>threaded environments:</h4>
2918
2919<p>Since the catalog tree is built progressively, some care has been taken to
2920try to avoid troubles in multithreaded environments. The code is now thread
2921safe assuming that the libxml library has been compiled with threads
2922support.</p>
2923
2924<p></p>
2925
2926<h3><a name="Other">Other resources</a></h3>
2927
2928<p>The XML Catalog specification is relatively recent so there isn't much
2929literature to point at:</p>
2930<ul>
2931 <li>You can find an good rant from Norm Walsh about <a
2932 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2933 need for catalogs</a>, it provides a lot of context informations even if
2934 I don't agree with everything presented.</li>
2935 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2936 catalog proposal</a> from John Cowan</li>
2937 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2938 Language</a> (RDDL) another catalog system but more oriented toward
2939 providing metadata for XML namespaces.</li>
2940 <li>the page from the OASIS Technical <a
2941 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2942 Resolution</a> who maintains XML Catalog, you will find pointers to the
2943 specification update, some background and pointers to others tools
2944 providing XML Catalog support</li>
Daniel Veillard35e937a2002-01-19 22:21:54 +00002945 <li>Here is a <a href="buildDocBookCatalog">shell script</a> to generate
2946 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/
2947 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on
2948 the resources found on the system. Otherwise it will just create
2949 ~/xmlcatalog and ~/dbkxmlcatalog and doing:
Daniel Veillardc575b992002-02-08 13:28:40 +00002950 <p><code>export XMLCATALOG=$HOME/xmlcatalog</code></p>
Daniel Veillard35e937a2002-01-19 22:21:54 +00002951 <p>should allow to process DocBook documentations without requiring
2952 network accesses for the DTd or stylesheets</p>
2953 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002954 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
Daniel Veillard35e937a2002-01-19 22:21:54 +00002955 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems
2956 to work fine for me too</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00002957 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2958 manual page</a></li>
2959</ul>
2960
2961<p>If you have suggestions for corrections or additions, simply contact
2962me:</p>
2963
2964<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002965
2966<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00002967using the XML library from the C language. It is not intended to be
2968extensive. I hope the automatically generated documents will provide the
2969completeness required, but as a separate set of documents. The interfaces of
2970the XML library are by principle low level, there is nearly zero abstraction.
2971Those interested in a higher level API should <a href="#DOM">look at
2972DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +00002973
Daniel Veillard9cb5ff42001-01-29 08:22:21 +00002974<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2975separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +00002976interfaces</a>. Let's have a look at how the XML parser can be called:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +00002977
Daniel Veillard88f00ae2000-03-02 00:15:55 +00002978<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002979
Daniel Veillard88f00ae2000-03-02 00:15:55 +00002980<p>Usually, the first thing to do is to read an XML input. The parser accepts
2981documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +00002982defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00002983<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002984 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00002985 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002986 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00002987</dl>
2988<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002989 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00002990 <dd><p>Parse an XML document contained in a (possibly compressed)
2991 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002992 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00002993</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002994
Daniel Veillard88f00ae2000-03-02 00:15:55 +00002995<p>The parser returns a pointer to the document structure (or NULL in case of
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00002996failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00002997
Daniel Veillard88f00ae2000-03-02 00:15:55 +00002998<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +00002999
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003000<p>In order for the application to keep the control when the document is
3001being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003002interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +00003003<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
3004 void *user_data,
3005 const char *chunk,
3006 int size,
3007 const char *filename);
3008int xmlParseChunk (xmlParserCtxtPtr ctxt,
3009 const char *chunk,
3010 int size,
3011 int terminate);</pre>
3012
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003013<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +00003014<pre> FILE *f;
3015
3016 f = fopen(filename, "r");
3017 if (f != NULL) {
3018 int res, size = 1024;
3019 char chars[1024];
3020 xmlParserCtxtPtr ctxt;
3021
3022 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +00003023 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +00003024 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
3025 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +00003026 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +00003027 xmlParseChunk(ctxt, chars, res, 0);
3028 }
3029 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +00003030 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +00003031 xmlFreeParserCtxt(ctxt);
3032 }
3033 }</pre>
3034
Daniel Veillardec70e912001-02-26 20:10:45 +00003035<p>The HTML parser embedded into libxml also has a push interface; the
3036functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +00003037
3038<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
3039
Daniel Veillardec70e912001-02-26 20:10:45 +00003040<p>The tree-building interface makes the parser memory-hungry, first loading
3041the document in memory and then building the tree itself. Reading a document
3042without building the tree is possible using the SAX interfaces (see SAX.h and
3043<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003044Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +00003045limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +00003046<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +00003047
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003048<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003049
3050<p>The other way to get an XML tree in memory is by building it. Basically
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003051there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003052also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
3053code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003054<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +00003055 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +00003056 xmlNodePtr tree, subtree;
3057
3058 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +00003059 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
3060 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
3061 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
3062 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +00003063 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +00003064 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +00003065 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
3066 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
3067 subtree = xmlNewChild(tree, NULL, "image", NULL);
3068 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003069
3070<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +00003071
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003072<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003073
Daniel Veillard9cb5ff42001-01-29 08:22:21 +00003074<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003075code has access to the internal structure of all the elements of the tree.
3076The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +00003077<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003078<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +00003079example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003080<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003081
3082<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +00003083<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003084
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003085<p>points to the text node containing the chapter title "The Linux
3086adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00003087
Daniel Veillardb24054a1999-12-18 15:32:46 +00003088<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard60979bd2000-07-10 12:17:33 +00003089present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +00003090to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +00003091<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +00003092
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003093<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003094
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003095<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +00003096is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +00003097<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +00003098 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
3099 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003100 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
3101 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003102 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003103</dl>
3104<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +00003105 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +00003106 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +00003107 <dd><p>This function returns a pointer to new copy of the property
3108 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003109 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003110</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003111
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003112<p>Two functions are provided for reading and writing the text associated
3113with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +00003114<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +00003115 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +00003116 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +00003117 <dd><p>This function takes an "external" string and converts it to one
3118 text node or possibly to a list of entity and text nodes. All
3119 non-predefined entity references like &amp;Gnome; will be stored
3120 internally as entity nodes, hence the result of the function may not be
3121 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003122 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003123</dl>
3124<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +00003125 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +00003126 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003127 <dd><p>This function is the inverse of
3128 <code>xmlStringGetNodeList()</code>. It generates a new string
3129 containing the content of the text and entity nodes. Note the extra
3130 argument inLine. If this argument is set to 1, the function will expand
3131 entity references. For example, instead of returning the &amp;Gnome;
3132 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +00003133 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003134 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003135</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00003136
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003137<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003138
3139<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +00003140<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +00003141 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +00003142 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003143 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003144 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003145</dl>
3146<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003147 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003148 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003149 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003150</dl>
3151<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003152 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003153 <dd><p>Saves the document to a file. In this case, the compression
3154 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003155 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003156</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +00003157
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003158<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003159
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003160<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003161accesses. The level of compression on saves can be turned on either globally
3162or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +00003163<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003164 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003165 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003166 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003167</dl>
3168<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003169 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003170 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003171 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003172</dl>
3173<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003174 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003175 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003176 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003177</dl>
3178<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003179 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003180 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003181 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +00003182</dl>
3183
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003184<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003185
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003186<p>Entities in principle are similar to simple C macros. An entity defines an
3187abbreviation for a given string that you can reuse many times throughout the
3188content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003189may occur frequently within a document, or to confine the change needed to a
3190document to a restricted area in the internal subset of the document (at the
3191beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003192<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +000031932 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +000031943 &lt;!ENTITY xml "Extensible Markup Language"&gt;
31954 ]&gt;
31965 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +000031976 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +000031987 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003199
3200<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard91e9d582001-02-26 07:31:12 +00003201its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003202are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003203predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003204<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003205for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003206<strong>&amp;quot;</strong> for the character '"', and
3207<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003208
3209<p>One of the problems related to entities is that you may want the parser to
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003210substitute an entity's content so that you can see the replacement text in
3211your application. Or you may prefer to keep entity references as such in the
3212content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003213precious information (if the user went through the pain of explicitly
3214defining entities, he may have a a rather negative attitude if you blindly
3215susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +00003216href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003217function allows you to check and change the behaviour, which is to not
3218substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003219
3220<p>Here is the DOM tree built by libxml for the previous document in the
3221default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003222<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003223DOCUMENT
3224version=1.0
3225 ELEMENT EXAMPLE
3226 TEXT
3227 content=
3228 ENTITY_REF
3229 INTERNAL_GENERAL_ENTITY xml
3230 content=Extensible Markup Language
3231 TEXT
3232 content=</pre>
3233
3234<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003235<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003236DOCUMENT
3237version=1.0
3238 ELEMENT EXAMPLE
3239 TEXT
3240 content= Extensible Markup Language</pre>
3241
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003242<p>So, entities or no entities? Basically, it depends on your use case. I
3243suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003244entities in your XML document or data if you are not willing to handle the
3245entity references elements in the DOM tree.</p>
3246
Daniel Veillard91e9d582001-02-26 07:31:12 +00003247<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003248entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +00003249transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003250reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003251finding them in the input).</p>
3252
Daniel Veillard7b9c4b72000-08-25 16:26:50 +00003253<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +00003254on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +00003255non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +00003256then using the SAX API may be long. If you plan to use complex documents, I
Daniel Veillard7b9c4b72000-08-25 16:26:50 +00003257strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +00003258deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +00003259
Daniel Veillard2f4dfc41999-09-24 14:03:48 +00003260<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003261
Daniel Veillardec303412000-03-24 13:41:54 +00003262<p>The libxml library implements <a
3263href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
3264recognizing namespace contructs in the input, and does namespace lookup
3265automatically when building the DOM tree. A namespace declaration is
3266associated with an in-memory structure and all elements or attributes within
3267that namespace point to it. Hence testing the namespace is a simple and fast
3268equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003269
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003270<p>I suggest that people using libxml use a namespace, and declare it in the
3271root element of their document as the default namespace. Then they don't need
3272to use the prefix in the content but we will have a basis for future semantic
Daniel Veillard91e9d582001-02-26 07:31:12 +00003273refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +00003274the size of the XML output significantly, but significantly increases its
3275value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003276<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
3277 &lt;elem1&gt;...&lt;/elem1&gt;
3278 &lt;elem2&gt;...&lt;/elem2&gt;
3279&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003280
Daniel Veillardec70e912001-02-26 20:10:45 +00003281<p>The namespace value has to be an absolute URL, but the URL doesn't have to
3282point to any existing resource on the Web. It will bind all the element and
3283atributes with that URL. I suggest to use an URL within a domain you control,
3284and that the URL should contain some kind of version information if possible.
3285For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
3286namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +00003287
3288<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +00003289version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003290and if the version information don't match something you know, warn the user
3291and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard60979bd2000-07-10 12:17:33 +00003292namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +00003293same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +00003294associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +00003295just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +00003296<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +00003297prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003298
3299<p>@@Interfaces@@</p>
3300
3301<p>@@Examples@@</p>
3302
Daniel Veillard91e9d582001-02-26 07:31:12 +00003303<p>Usually people object to using namespaces together with validity checking.
3304I will try to make sure that using namespaces won't break validity checking,
3305so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +00003306suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003307<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +00003308flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003309from multiple DTDs will certainly break current validation schemes. I will
3310try to provide ways to do this, but this may not be portable or
3311standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003312
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003313<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003314
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003315<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003316
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003317<p>Version 2 of libxml is the first version introducing serious backward
3318incompatible changes. The main goals were:</p>
3319<ul>
3320 <li>a general cleanup. A number of mistakes inherited from the very early
3321 versions couldn't be changed due to compatibility constraints. Example
3322 the "childs" element in the nodes.</li>
3323 <li>Uniformization of the various nodes, at least for their header and link
3324 parts (doc, parent, children, prev, next), the goal is a simpler
3325 programming model and simplifying the task of the DOM implementors.</li>
3326 <li>better conformances to the XML specification, for example version 1.x
3327 had an heuristic to try to detect ignorable white spaces. As a result the
3328 SAX event generated were ignorableWhitespace() while the spec requires
3329 character() in that case. This also mean that a number of DOM node
3330 containing blank text may populate the DOM tree which were not present
3331 before.</li>
3332</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003333
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003334<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003335
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003336<p>So client code of libxml designed to run with version 1.x may have to be
3337changed to compile against version 2.x of libxml. Here is a list of changes
3338that I have collected, they may not be sufficient, so in case you find other
3339change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
3340mail</a>:</p>
3341<ol>
3342 <li>The package name have changed from libxml to libxml2, the library name
3343 is now -lxml2 . There is a new xml2-config script which should be used to
3344 select the right parameters libxml2</li>
3345 <li>Node <strong>childs</strong> field has been renamed
3346 <strong>children</strong> so s/childs/children/g should be applied
3347 (probablility of having "childs" anywere else is close to 0+</li>
3348 <li>The document don't have anymore a <strong>root</strong> element it has
3349 been replaced by <strong>children</strong> and usually you will get a
3350 list of element here. For example a Dtd element for the internal subset
3351 and it's declaration may be found in that list, as well as processing
3352 instructions or comments found before or after the document root element.
3353 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
3354 a document. Alternatively if you are sure to not reference Dtds nor have
3355 PIs or comments before or after the root element
3356 s/-&gt;root/-&gt;children/g will probably do it.</li>
3357 <li>The white space issue, this one is more complex, unless special case of
3358 validating parsing, the line breaks and spaces usually used for indenting
3359 and formatting the document content becomes significant. So they are
3360 reported by SAX and if your using the DOM tree, corresponding nodes are
3361 generated. Too approach can be taken:
3362 <ol>
3363 <li>lazy one, use the compatibility call
3364 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
3365 relying on a special (and possibly broken) set of heuristics of
3366 libxml to detect ignorable blanks. Don't complain if it breaks or
3367 make your application not 100% clean w.r.t. to it's input.</li>
3368 <li>the Right Way: change you code to accept possibly unsignificant
3369 blanks characters, or have your tree populated with weird blank text
3370 nodes. You can spot them using the comodity function
3371 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
3372 nodes.</li>
3373 </ol>
3374 <p>Note also that with the new default the output functions don't add any
3375 extra indentation when saving a tree in order to be able to round trip
3376 (read and save) without inflating the document with extra formatting
3377 chars.</p>
3378 </li>
3379 <li>The include path has changed to $prefix/libxml/ and the includes
3380 themselves uses this new prefix in includes instructions... If you are
3381 using (as expected) the
3382 <pre>xml2-config --cflags</pre>
3383 <p>output to generate you compile commands this will probably work out of
3384 the box</p>
3385 </li>
3386 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
3387 byte of the head of the document available for character detection.</li>
3388</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003389
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003390<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003391
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003392<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3393to allow smoth upgrade of existing libxml v1code while retaining
3394compatibility. They offers the following:</p>
3395<ol>
3396 <li>similar include naming, one should use
3397 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3398 <li>similar identifiers defined via macros for the child and root fields:
3399 respectively <strong>xmlChildrenNode</strong> and
3400 <strong>xmlRootNode</strong></li>
3401 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3402 inserted once in the client code</li>
3403</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003404
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003405<p>So the roadmap to upgrade your existing libxml applications is the
3406following:</p>
3407<ol>
3408 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3409 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3410 used and change it to <strong>xmlRootNode</strong></li>
3411 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3412 field is used and change it to <strong>xmlChildrenNode</strong></li>
3413 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3414 <strong>main()</strong> or in the library init entry point</li>
3415 <li>Recompile, check compatibility, it should still work</li>
3416 <li>Change your configure script to look first for xml2-config and fallback
3417 using xml-config . Use the --cflags and --libs ouptut of the command as
3418 the Include and Linking parameters needed to use libxml.</li>
3419 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3420 libxml-devel-1.8.y can be kept simultaneously)</li>
3421 <li>remove your config.cache, relaunch your configuration mechanism, and
3422 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3423 <li>Test that your application is still running correctly, if not this may
3424 be due to extra empty nodes due to formating spaces being kept in libxml2
3425 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3426 code before calling the parser (next to
3427 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3428</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003429
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003430<p>Following those steps should work. It worked for some of my own code.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003431
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003432<p>Let me put some emphasis on the fact that there is far more changes from
3433libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3434has been considerably cleaned up and the conformance to the XML specification
3435has been drastically improved too. Don't take those changes as an excuse to
3436not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003437
Daniel Veillard52dcab32001-10-30 12:51:17 +00003438<h2><a name="Thread">Thread safety</a></h2>
3439
3440<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3441threads can safely work in parallel parsing different documents. There is
3442however a couple of things to do to ensure it:</p>
3443<ul>
3444 <li>configure the library accordingly using the --with-threads options</li>
3445 <li>call xmlInitParser() in the "main" thread before using any of the
3446 libxml API (except possibly selecting a different memory allocator)</li>
3447</ul>
3448
3449<p>Note that the thread safety cannot be ensured for multiple threads sharing
3450the same document, the locking must be done at the application level, libxml
3451exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3452The parts of the library checked for thread safety are:</p>
3453<ul>
3454 <li>concurrent loading</li>
3455 <li>file access resolution</li>
3456 <li>catalog access</li>
3457 <li>catalog building</li>
3458 <li>entities lookup/accesses</li>
3459 <li>validation</li>
3460 <li>global variables per-thread override</li>
3461 <li>memory handling</li>
3462</ul>
3463
3464<p>XPath is supposed to be thread safe now, but this wasn't tested
3465seriously.</p>
3466
Daniel Veillard35008381999-10-25 13:15:52 +00003467<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003468
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003469<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3470Object Model</em>; this is an API for accessing XML or HTML structured
3471documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3472and will be based on gnome-xml. This will be a far cleaner interface to
3473manipulate XML files within Gnome since it won't expose the internal
3474structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +00003475
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003476<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +00003477href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3478is a full DOM interface, thanks to Paolo Casarini, check the <a
3479href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3480informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003481
Daniel Veillard35008381999-10-25 13:15:52 +00003482<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003483
3484<p>Here is a real size example, where the actual content of the application
3485data is not kept in the DOM tree but uses internal structures. It is based on
Daniel Veillard14fff061999-06-22 21:49:07 +00003486a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +00003487storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3488base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003489<pre>&lt;?xml version="1.0"?&gt;
3490&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3491 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003492
Daniel Veillard60979bd2000-07-10 12:17:33 +00003493 &lt;gjob:Job&gt;
3494 &lt;gjob:Project ID="3"/&gt;
3495 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3496 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003497
Daniel Veillard60979bd2000-07-10 12:17:33 +00003498 &lt;gjob:Update&gt;
3499 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3500 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3501 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3502 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003503
Daniel Veillard60979bd2000-07-10 12:17:33 +00003504 &lt;gjob:Developers&gt;
3505 &lt;gjob:Developer&gt;
3506 &lt;/gjob:Developer&gt;
3507 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003508
Daniel Veillard60979bd2000-07-10 12:17:33 +00003509 &lt;gjob:Contact&gt;
3510 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3511 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3512 &lt;gjob:Company&gt;
3513 &lt;/gjob:Company&gt;
3514 &lt;gjob:Organisation&gt;
3515 &lt;/gjob:Organisation&gt;
3516 &lt;gjob:Webpage&gt;
3517 &lt;/gjob:Webpage&gt;
3518 &lt;gjob:Snailmail&gt;
3519 &lt;/gjob:Snailmail&gt;
3520 &lt;gjob:Phone&gt;
3521 &lt;/gjob:Phone&gt;
3522 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003523
Daniel Veillard60979bd2000-07-10 12:17:33 +00003524 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003525 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +00003526 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003527
Daniel Veillard60979bd2000-07-10 12:17:33 +00003528 &lt;gjob:Skills&gt;
3529 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003530
Daniel Veillard60979bd2000-07-10 12:17:33 +00003531 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003532 A GNOME based system that will allow a superuser to configure
3533 compressed and uncompressed files and/or file systems to be backed
3534 up with a supported media in the system. This should be able to
3535 perform via find commands generating a list of files that are passed
3536 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3537 or via operations performed on the filesystem itself. Email
3538 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +00003539 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003540
Daniel Veillard60979bd2000-07-10 12:17:33 +00003541 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +00003542
Daniel Veillard60979bd2000-07-10 12:17:33 +00003543 &lt;/gjob:Jobs&gt;
3544&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003545
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003546<p>While loading the XML file into an internal DOM tree is a matter of
3547calling only a couple of functions, browsing the tree to gather the ata and
3548generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003549
3550<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003551structure. For example, the ordering of the attributes is not significant,
3552the XML specification is clear about it. It's also usually a good idea not to
Daniel Veillardec70e912001-02-26 20:10:45 +00003553depend on the order of the children of a given node, unless it really makes
3554things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003555<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +00003556 * A person record
3557 */
3558typedef struct person {
3559 char *name;
3560 char *email;
3561 char *company;
3562 char *organisation;
3563 char *smail;
3564 char *webPage;
3565 char *phone;
3566} person, *personPtr;
3567
3568/*
3569 * And the code needed to parse it
3570 */
3571personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3572 personPtr ret = NULL;
3573
3574DEBUG("parsePerson\n");
3575 /*
3576 * allocate the struct
3577 */
3578 ret = (personPtr) malloc(sizeof(person));
3579 if (ret == NULL) {
3580 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +00003581 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +00003582 }
3583 memset(ret, 0, sizeof(person));
3584
3585 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +00003586 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +00003587 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +00003588 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3589 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3590 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3591 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3592 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +00003593 }
3594
3595 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +00003596}</pre>
3597
Daniel Veillard91e9d582001-02-26 07:31:12 +00003598<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +00003599<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +00003600 <li>Usually a recursive parsing style is the more convenient one: XML data
3601 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +00003602 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003603 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3604 i.e. the pointer to the global XML document and the namespace reserved to
3605 the application. Document wide information are needed for example to
3606 decode entities and it's a good coding practice to define a namespace for
3607 your application set of data and test that the element and attributes
3608 you're analyzing actually pertains to your application space. This is
3609 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +00003610 <li>To retrieve text and attributes value, you can use the function
3611 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3612 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +00003613</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003614
3615<p>Here is another piece of code used to parse another level of the
3616structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +00003617<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +00003618/*
Daniel Veillard14fff061999-06-22 21:49:07 +00003619 * a Description for a Job
3620 */
3621typedef struct job {
3622 char *projectID;
3623 char *application;
3624 char *category;
3625 personPtr contact;
3626 int nbDevelopers;
3627 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3628} job, *jobPtr;
3629
3630/*
3631 * And the code needed to parse it
3632 */
3633jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3634 jobPtr ret = NULL;
3635
3636DEBUG("parseJob\n");
3637 /*
3638 * allocate the struct
3639 */
3640 ret = (jobPtr) malloc(sizeof(job));
3641 if (ret == NULL) {
3642 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +00003643 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +00003644 }
3645 memset(ret, 0, sizeof(job));
3646
3647 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +00003648 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +00003649 while (cur != NULL) {
3650
Daniel Veillard60979bd2000-07-10 12:17:33 +00003651 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3652 ret-&gt;projectID = xmlGetProp(cur, "ID");
3653 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +00003654 fprintf(stderr, "Project has no ID\n");
3655 }
3656 }
Daniel Veillard60979bd2000-07-10 12:17:33 +00003657 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3658 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3659 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3660 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3661 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3662 ret-&gt;contact = parsePerson(doc, ns, cur);
3663 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +00003664 }
3665
3666 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +00003667}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +00003668
Daniel Veillardec70e912001-02-26 20:10:45 +00003669<p>Once you are used to it, writing this kind of code is quite simple, but
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +00003670boring. Ultimately, it could be possble to write stubbers taking either C
3671data structure definitions, a set of XML examples or an XML DTD and produce
3672the code needed to import and export the content between C data and XML
3673storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003674
Daniel Veillard6f0adb52000-07-03 11:41:26 +00003675<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3676parsing example</a> as a template, it is also available with Makefile in the
3677Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +00003678
Daniel Veillardc310d562000-06-23 18:32:15 +00003679<h2><a name="Contributi">Contributions</a></h2>
3680<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +00003681 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3682 patches, Gary Pennington worked on the validation API, threading support
3683 and Solaris port.</li>
3684 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +00003685 <li><a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
3686 for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +00003687 Website: <a
3688 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3689 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +00003690 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +00003691 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the
3692 maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +00003693 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3694 provides binaries</a></li>
Daniel Veillardaf43f632002-03-08 15:05:20 +00003695 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a> provides
3696 <a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +00003697 <li><a
3698 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +00003699 Sergeant</a> developped <a
3700 href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
3701 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
3702 application server</a></li>
3703 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a> and <a
3704 href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +00003705 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +00003706 documentation</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +00003707 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a> provided <a
3708 href="http://xmlsoft.org/messages/0488.html">man pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +00003709 <li>there is a module for <a
3710 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3711 in OpenNSD/AOLServer</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +00003712 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provided the
3713 first version of libxml/libxslt <a
3714 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
Daniel Veillard1aadc442001-11-28 13:10:32 +00003715 <li>Petr Kozelka provides <a
3716 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
3717 libxml2</a> with Kylix and Delphi and other Pascal compilers</li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +00003718 <li><a href="mailto:aleksey@aleksey.com">Aleksey Sanin</a> implemented the
3719 <a href="http://www.w3.org/Signature/">XML Canonicalization and XML
3720 Digital Signature</a> <a
3721 href="http://www.aleksey.com/xmlsec/">implementations for libxml2</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +00003722</ul>
3723
Daniel Veillardc8eab3a1999-09-04 18:27:23 +00003724<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +00003725</body>
3726</html>