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blob: 3bb0555775b3839a607691cbe6fe0155a2d8ed47 [file] [log] [blame]
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]1<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
2 "http://www.w3.org/TR/html4/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]5 <title>The XML C library for Gnome</title>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V5.0">
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]7 <meta http-equiv="Content-Type" content="text/html">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]8</head>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]9
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]10<body bgcolor="#ffffff">
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]11<h1 align="center">The XML C library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]12
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]13<h1>Note: this is the flat content of the <a href="index.html">web
14site</a></h1>
15
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]16<h1 style="text-align: center">libxml, a.k.a. gnome-xml</h1>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17
18<p></p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]19
20<p>Libxml is the XML C library developped for the Gnome project. XML itself
21is a metalanguage to design markup languages, i.e. text language where
22semantic and structure are added to the content using extra "markup"
23information enclosed between angle bracket. HTML is the most well-known
24markup language.</p>
25
26<p>Libxml2 implements a number of existing standards related to markup
27languages:</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]28<ul>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]29 <li>the XML standard: <a
30 href="http://www.w3.org/TR/REC-xml">http://www.w3.org/TR/REC-xml</a></li>
31 <li>Namespaces in XML: <a
32 href="http://www.w3.org/TR/REC-xml-names/">http://www.w3.org/TR/REC-xml-names/</a></li>
33 <li>XML Base: <a
34 href="http://www.w3.org/TR/xmlbase/">http://www.w3.org/TR/xmlbase/</a></li>
35 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc2396.txt">RFC 2396</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]36 : Uniform Resource Identifiers <a
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]37 href="http://www.ietf.org/rfc/rfc2396.txt">http://www.ietf.org/rfc/rfc2396.txt</a></li>
38 <li>XML Path Language (XPath) 1.0: <a
39 href="http://www.w3.org/TR/xpath">http://www.w3.org/TR/xpath</a></li>
40 <li>HTML4 parser: <a
41 href="http://www.w3.org/TR/html401/">http://www.w3.org/TR/html401/</a></li>
42 <li>most of XML Pointer Language (XPointer) Version 1.0: <a
43 href="http://www.w3.org/TR/xptr">http://www.w3.org/TR/xptr</a></li>
44 <li>XML Inclusions (XInclude) Version 1.0: <a
45 href="http://www.w3.org/TR/xinclude/">http://www.w3.org/TR/xinclude/</a></li>
46 <li>[ISO-8859-1], <a
47 href="http://www.cis.ohio-state.edu/rfc/rfc2044.txt">rfc2044</a> [UTF-8]
48 and <a href="http://www.cis.ohio-state.edu/rfc/rfc2781.txt">rfc2781</a>
49 [UTF-16] core encodings</li>
50 <li>part of SGML Open Technical Resolution TR9401:1997</li>
51 <li>XML Catalogs Working Draft 06 August 2001: <a
52 href="http://www.oasis-open.org/committees/entity/spec-2001-08-06.html">http://www.oasis-open.org/committees/entity/spec-2001-08-06.html</a></li>
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]53</ul>
54
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]55<p>In most cases libxml tries to implement the specifications in a relatively
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]56strict way. As of release 2.4.16, libxml2 passes all 1800+ tests from the <a
57href="http://www.oasis-open.org/committees/xml-conformance/">OASIS XML Tests
58Suite</a>.</p>
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]59
60<p>To some extent libxml2 provide some support for the following other
61specification but don't claim to implement them:</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]62<ul>
63 <li>Document Object Model (DOM) <a
64 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
65 it doesn't implement the API itself, gdome2 does this in top of
66 libxml2</li>
67 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc959.txt">RFC 959</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]68 : libxml implements a basic FTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]69 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]70 : HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]71 <li>SAX: a minimal SAX implementation compatible with early expat
72 versions</li>
73 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
74 XML</li>
75</ul>
76
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]77<p>Libxml2 is known to be very portable, should build and work without
78serious troubles on a variety of systems (Linux, Unix, Windows, CygWin,
79MacOs, MacOsX, RISC Os, OS/2, VMS, QNX, MVS, ...)</p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]80
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]81<p>Separate documents:</p>
82<ul>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]83 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a>
84 providing an implementation of XSLT 1.0 and extensions on top of
85 libxml2</li>
86 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]87 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]88</ul>
89
90<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]91
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]92<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]93href="http://www.w3.org/XML/">XML</a> C library developped for the <a
94href="http://www.gnome.org/">Gnome</a> project. <a
95href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
96structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]97
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]98<p>Here are some key points about libxml:</p>
99<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]100 <li>Libxml exports Push and Pull type parser interfaces for both XML and
101 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]102 <li>Libxml can do DTD validation at parse time, using a parsed document
103 instance, or with an arbitrary DTD.</li>
104 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]105 href="http://www.w3.org/TR/xpath">XPath</a>, <a
106 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
107 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]108 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]109 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]110 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]111 <li>Basic support for HTTP and FTP client allowing aplications to fetch
112 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]113 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]114 <li>The internal document repesentation is as close as possible to the <a
115 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
116 <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]117 like interface</a>; the interface is designed to be compatible with <a
118 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]119 <li>This library is released under the <a
120 href="http://www.opensource.org/licenses/mit-license.html">MIT
121 Licence</a> see the Copyright file in the distribution for the precise
122 wording.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]123</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]124
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]125<p>Warning: unless you are forced to because your application links with a
126Gnome library requiring it, <strong><span
127style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
128libxml2</p>
129
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]130<h2><a name="FAQ">FAQ</a></h2>
131
132<p>Table of Content:</p>
133<ul>
134 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
135 <li><a href="FAQ.html#Installati">Installation</a></li>
136 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
137 <li><a href="FAQ.html#Developer">Developer corner</a></li>
138</ul>
139
140<h3><a name="Licence">Licence</a>(s)</h3>
141<ol>
142 <li><em>Licensing Terms for libxml</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]143 <p>libxml is released under the <a
144 href="http://www.opensource.org/licenses/mit-license.html">MIT
145 Licence</a>, see the file Copyright in the distribution for the precise
146 wording</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]147 </li>
148 <li><em>Can I embed libxml in a proprietary application ?</em>
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]149 <p>Yes. The MIT Licence allows you to also keep proprietary the changes
150 you made to libxml, but it would be graceful to provide back bugfixes and
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]151 improvements as patches for possible incorporation in the main
152 development tree</p>
153 </li>
154</ol>
155
156<h3><a name="Installati">Installation</a></h3>
157<ol>
158 <li>Unless you are forced to because your application links with a Gnome
159 library requiring it, <strong><span style="background-color: #FF0000">Do
160 Not Use libxml1</span></strong>, use libxml2</li>
161 <li><em>Where can I get libxml</em>
162 ?
163 <p>The original distribution comes from <a
164 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
165 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
166 <p>Most linux and Bsd distribution includes libxml, this is probably the
167 safer way for end-users</p>
168 <p>David Doolin provides precompiled Windows versions at <a
169 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
170 </li>
171 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
172 <ul>
173 <li>If you are not concerned by any existing backward compatibility
174 with existing application, install libxml2 only</li>
175 <li>If you are not doing development, you can safely install both.
176 usually the packages <a
177 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
178 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
179 compatible (this is not the case for development packages)</li>
180 <li>If you are a developer and your system provides separate packaging
181 for shared libraries and the development components, it is possible
182 to install libxml and libxml2, and also <a
183 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
184 and <a
185 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
186 too for libxml2 &gt;= 2.3.0</li>
187 <li>If you are developing a new application, please develop against
188 libxml2(-devel)</li>
189 </ul>
190 </li>
191 <li><em>I can't install the libxml package it conflicts with libxml0</em>
192 <p>You probably have an old libxml0 package used to provide the shared
193 library for libxml.so.0, you can probably safely remove it. Anyway the
194 libxml packages provided on <a
195 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
196 libxml.so.0</p>
197 </li>
198 <li><em>I can't install the libxml(2) RPM package due to failed
199 dependancies</em>
200 <p>The most generic solution is to refetch the latest src.rpm , and
201 rebuild it locally with</p>
202 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
203 <p>if everything goes well it will generate two binary rpm (one providing
204 the shared libs and xmllint, and the other one, the -devel package
205 providing includes, static libraries and scripts needed to build
206 applications with libxml(2)) that you can install locally.</p>
207 </li>
208</ol>
209
210<h3><a name="Compilatio">Compilation</a></h3>
211<ol>
212 <li><em>What is the process to compile libxml ?</em>
213 <p>As most UNIX libraries libxml follows the "standard":</p>
214 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
215 <p><code>cd libxml-xxxx</code></p>
216 <p><code>./configure --help</code></p>
217 <p>to see the options, then the compilation/installation proper</p>
218 <p><code>./configure [possible options]</code></p>
219 <p><code>make</code></p>
220 <p><code>make install</code></p>
221 <p>At that point you may have to rerun ldconfig or similar utility to
222 update your list of installed shared libs.</p>
223 </li>
224 <li><em>What other libraries are needed to compile/install libxml ?</em>
225 <p>Libxml does not requires any other library, the normal C ANSI API
226 should be sufficient (please report any violation to this rule you may
227 find).</p>
228 <p>However if found at configuration time libxml will detect and use the
229 following libs:</p>
230 <ul>
231 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
232 : a highly portable and available widely compression library</li>
233 <li>iconv: a powerful character encoding conversion library. It's
234 included by default on recent glibc libraries, so it doesn't need to
235 be installed specifically on linux. It seems it's now <a
236 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
237 of the official UNIX</a> specification. Here is one <a
238 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
239 of the library</a> which source can be found <a
240 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
241 </ul>
242 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]243 <li><em>make check fails on some platforms</em>
244 <p>Sometime the regression tests results don't completely match the value
245 produced by the parser, and the makefile uses diff to print the delta. On
246 some platforms the diff return breaks the compilation process, if the
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]247 diff is small this is probably not a serious problem.</p>
248 <p>Sometimes (especially on Solaris) make checks fails due to limitations
249 in make. Try using GNU-make instead.</p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]250 </li>
251 <li><em>I use the CVS version and there is no configure script</em>
252 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
253 script to regenerate the configure and Makefiles, like:</p>
254 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
255 </li>
256 <li><em>I have troubles when running make tests with gcc-3.0</em>
257 <p>It seems the initial release of gcc-3.0 has a problem with the
258 optimizer which miscompiles the URI module. Please use another
259 compiler</p>
260 </li>
261</ol>
262
263<h3><a name="Developer">Developer</a> corner</h3>
264<ol>
265 <li><em>xmlDocDump() generates output on one line</em>
266 <p>libxml will not <strong>invent</strong> spaces in the content of a
267 document since <strong>all spaces in the content of a document are
268 significant</strong>. If you build a tree from the API and want
269 indentation:</p>
270 <ol>
271 <li>the correct way is to generate those yourself too</li>
272 <li>the dangerous way is to ask libxml to add those blanks to your
273 content <strong>modifying the content of your document in the
274 process</strong>. The result may not be what you expect. There is
275 <strong>NO</strong> way to guarantee that such a modification won't
276 impact other part of the content of your document. See <a
277 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
278 ()</a> and <a
279 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
280 ()</a></li>
281 </ol>
282 </li>
283 <li>Extra nodes in the document:
284 <p><em>For a XML file as below:</em></p>
285 <pre>&lt;?xml version="1.0"?&gt;
286&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
287&lt;NODE CommFlag="0"/&gt;
288&lt;NODE CommFlag="1"/&gt;
289&lt;/PLAN&gt;</pre>
290 <p><em>after parsing it with the function
291 pxmlDoc=xmlParseFile(...);</em></p>
292 <p><em>I want to the get the content of the first node (node with the
293 CommFlag="0")</em></p>
294 <p><em>so I did it as following;</em></p>
295 <pre>xmlNodePtr pode;
296pnode=pxmlDoc-&gt;children-&gt;children;</pre>
297 <p><em>but it does not work. If I change it to</em></p>
298 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
299 <p><em>then it works. Can someone explain it to me.</em></p>
300 <p></p>
301 <p>In XML all characters in the content of the document are significant
302 <strong>including blanks and formatting line breaks</strong>.</p>
303 <p>The extra nodes you are wondering about are just that, text nodes with
304 the formatting spaces wich are part of the document but that people tend
305 to forget. There is a function <a
306 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
307 ()</a> to remove those at parse time, but that's an heuristic, and its
308 use should be limited to case where you are sure there is no
309 mixed-content in the document.</p>
310 </li>
311 <li><em>I get compilation errors of existing code like when accessing
312 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
313 <p>You are compiling code developed for libxml version 1 and using a
314 libxml2 development environment. Either switch back to libxml v1 devel or
315 even better fix the code to compile with libxml2 (or both) by <a
316 href="upgrade.html">following the instructions</a>.</p>
317 </li>
318 <li><em>I get compilation errors about non existing
319 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
320 fields</em>
321 <p>The source code you are using has been <a
322 href="upgrade.html">upgraded</a> to be able to compile with both libxml
323 and libxml2, but you need to install a more recent version:
324 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
325 </li>
326 <li><em>XPath implementation looks seriously broken</em>
327 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
328 a recent version, the implementation and debug of libxslt generated fixes
329 for most obvious problems.</p>
330 </li>
331 <li><em>The example provided in the web page does not compile</em>
332 <p>It's hard to maintain the documentation in sync with the code
333 &lt;grin/&gt; ...</p>
334 <p>Check the previous points 1/ and 2/ raised before, and send
335 patches.</p>
336 </li>
337 <li><em>Where can I get more examples and informations than in the web
338 page</em>
339 <p>Ideally a libxml book would be nice. I have no such plan ... But you
340 can:</p>
341 <ul>
342 <li>check more deeply the <a href="html/libxml-lib.html">existing
343 generated doc</a></li>
344 <li>looks for examples of use for libxml function using the Gnome code
345 for example the following will query the full Gnome CVs base for the
346 use of the <strong>xmlAddChild()</strong> function:
347 <p><a
348 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
349 <p>This may be slow, a large hardware donation to the gnome project
350 could cure this :-)</p>
351 </li>
352 <li><a
353 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
354 the libxml source</a>
355 , I try to write code as clean and documented as possible, so
356 looking at it may be helpful</li>
357 </ul>
358 </li>
359 <li>What about C++ ?
360 <p>libxml is written in pure C in order to allow easy reuse on a number
361 of platforms, including embedded systems. I don't intend to convert to
362 C++.</p>
363 <p>There is however a C++ wrapper provided by Ari Johnson
364 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
365 <p>Website: <a
366 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
367 <p>Download: <a
368 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
369 </li>
370 <li>How to validate a document a posteriori ?
371 <p>It is possible to validate documents which had not been validated at
372 initial parsing time or documents who have been built from scratch using
373 the API. Use the <a
374 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
375 function. It is also possible to simply add a Dtd to an existing
376 document:</p>
377 <pre>xmlDocPtr doc; /* your existing document */
378 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
379 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
380
381 doc-&gt;intSubset = dtd;
382 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
383 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
384 </pre>
385 </li>
386 <li>etc ...</li>
387</ol>
388
389<p></p>
390
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]391<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]392
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]393<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]394<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]395 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]396 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]397 documentation</a> automatically extracted from code comments (using <a
398 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
399 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]400 <li>Look at the documentation about <a href="encoding.html">libxml
401 internationalization support</a></li>
Daniel Veillardbc66f852002-01-14 09:49:20 +0000[diff] [blame]402 <li>This page provides a global overview and <a href="example.html">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]403 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]404 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
405 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]406 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
407 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]408 <li>George Lebl wrote <a
409 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]410 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]411 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
412 file</a></li>
413 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
414 starting a new project using libxml you should really use the 2.x
415 version.</li>
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]416 <li>And don't forget to look at the <a
417 href="http://mail.gnome.org/archives/xml/">mailing-list archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]418</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]419
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]420<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]421
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]422<p>Well, bugs or missing features are always possible, and I will make a
423point of fixing them in a timely fashion. The best way to report a bug is to
424use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
425bug tracking database</a> (make sure to use the "libxml" module name). I look
426at reports there regularly and it's good to have a reminder when a bug is
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]427still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]428
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]429<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]430href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
431href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]432href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
433please visit the <a
434href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
435follow the instructions. <strong>Do not send code, I won't debug it</strong>
436(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]437
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]438<p>Check the following <strong><span style="color: #FF0000">before
439posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]440<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]441 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]442 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
443 version</a>, and that the problem still shows up in those</li>
444 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
445 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]446 there is probably a fix available, similary check the <a
447 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]448 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]449 <li>make sure you can reproduce the bug with xmllint or one of the test
450 programs found in source in the distribution</li>
451 <li>Please send the command showing the error as well as the input (as an
452 attachement)</li>
453</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]454
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]455<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]456href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]457related I will approve it.. Please do not send me mail directly, it makes
458things really harder to track and in some cases I'm not the best person to
459answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]460
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]461<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]462probably be processed faster.</p>
463
464<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]465href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]466provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]467questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]468documentantion</a> is not as polished as I would like (i need to learn more
469about Docbook), but it's a good starting point.</p>
470
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]471<h2><a name="help">How to help</a></h2>
472
473<p>You can help the project in various ways, the best thing to do first is to
474subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]475href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
476href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]477database:</a>:</p>
478<ol>
479 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]480 <li>provide the diffs when you port libxml to a new platform. They may not
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]481 be integrated in all cases but help pinpointing portability problems
482 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]483 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]484 as HTML diffs).</li>
485 <li>provide new documentations pieces (translations, examples, etc ...)</li>
486 <li>Check the TODO file and try to close one of the items</li>
487 <li>take one of the points raised in the archive or the bug database and
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]488 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
489 </a>before to avoid synchronization problems and check that the suggested
490 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]491</ol>
492
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]493<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]494
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]495<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]496href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
497href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
498href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]499href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]500as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]501archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]502href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
503packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]504href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
505href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]506packages installed to compile applications using libxml.) <a
507href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
508of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]509href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]510provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]511Pennington</a> provides <a href="http://garypennington.net/libxml2/">Solaris
512binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]513
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]514<p><a name="Snapshot">Snapshot:</a></p>
515<ul>
516 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]517 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]518 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]519 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]520</ul>
521
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]522<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]523
524<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]525platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]526languages have been provided, and can be found in the <a
527href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]528
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]529<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]530<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]531 <li><p>The <a
532 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]533 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]534 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
535 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]536 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]537 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]538</ul>
539
540<h2><a name="News">News</a></h2>
541
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]542<h3>CVS only : check the <a
543href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]544for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]545
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]546<p>Items floating around but not actively worked on, get in touch with me if
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]547you want to test those</p>
548<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]549 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
550 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]551 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
552 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]553 <li>(seeems working but delayed from release) parsing/import of Docbook
554 SGML docs</li>
555</ul>
556
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]557<h3>2.4.16: Feb 20 2002</h3>
558<ul>
559 <li>a lot of bug fixes, most of them were triggered by the XML Testsuite
560 from OASIS and W3C. Compliance has been significantly improved.</li>
561 <li>a couple of portability fixes too.</li>
562</ul>
563
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]564<h3>2.4.15: Feb 11 2002</h3>
565<ul>
566 <li>Fixed the Makefiles, especially the python module ones</li>
567 <li>A few bug fixes and cleanup</li>
568 <li>Includes cleanup</li>
569</ul>
570
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]571<h3>2.4.14: Feb 8 2002</h3>
572<ul>
573 <li>Change of Licence to the <a
574 href="http://www.opensource.org/licenses/mit-license.html">MIT
575 Licence</a> basisally for integration in XFree86 codebase, and removing
576 confusion around the previous dual-licencing</li>
577 <li>added Python bindings, beta software but should already be quite
578 complete</li>
579 <li>a large number of fixes and cleanups, especially for all tree
580 manipulations</li>
581 <li>cleanup of the headers, generation of a reference API definition in
582 XML</li>
583</ul>
584
585<h3>2.4.13: Jan 14 2002</h3>
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]586<ul>
587 <li>update of the documentation: John Fleck and Charlie Bozeman</li>
588 <li>cleanup of timing code from Justin Fletcher</li>
589 <li>fixes for Windows and initial thread support on Win32: Igor and Serguei
590 Narojnyi</li>
591 <li>Cygwin patch from Robert Collins</li>
592 <li>added xmlSetEntityReferenceFunc() for Keith Isdale work on xsldbg</li>
593</ul>
594
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]595<h3>2.4.12: Dec 7 2001</h3>
596<ul>
597 <li>a few bug fixes: thread (Gary Pennington), xmllint (Geert Kloosterman),
598 XML parser (Robin Berjon), XPointer (Danny Jamshy), I/O cleanups
599 (robert)</li>
600 <li>Eric Lavigne contributed project files for MacOS</li>
601 <li>some makefiles cleanups</li>
602</ul>
603
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]604<h3>2.4.11: Nov 26 2001</h3>
605<ul>
606 <li>fixed a couple of errors in the includes, fixed a few bugs, some code
607 cleanups</li>
608 <li>xmllint man pages improvement by Heiko Rupp</li>
609 <li>updated VMS build instructions from John A Fotheringham</li>
610 <li>Windows Makefiles updates from Igor</li>
611</ul>
612
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]613<h3>2.4.10: Nov 10 2001</h3>
614<ul>
615 <li>URI escaping fix (Joel Young)</li>
616 <li>added xmlGetNodePath() (for paths or XPointers generation)</li>
617 <li>Fixes namespace handling problems when using DTD and validation</li>
618 <li>improvements on xmllint: Morus Walter patches for --format and
619 --encode, Stefan Kost and Heiko Rupp improvements on the --shell</li>
620 <li>fixes for xmlcatalog linking pointed by Weiqi Gao</li>
621 <li>fixes to the HTML parser</li>
622</ul>
623
624<h3>2.4.9: Nov 6 2001</h3>
625<ul>
626 <li>fixes more catalog bugs</li>
627 <li>avoid a compilation problem, improve xmlGetLineNo()</li>
628</ul>
629
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]630<h3>2.4.8: Nov 4 2001</h3>
631<ul>
632 <li>fixed SGML catalogs broken in previous release, updated xmlcatalog
633 tool</li>
634 <li>fixed a compile errors and some includes troubles.</li>
635</ul>
636
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]637<h3>2.4.7: Oct 30 2001</h3>
638<ul>
639 <li>exported some debugging interfaces</li>
640 <li>serious rewrite of the catalog code</li>
641 <li>integrated Gary Pennington thread safety patch, added configure option
642 and regression tests</li>
643 <li>removed an HTML parser bug</li>
644 <li>fixed a couple of potentially serious validation bugs</li>
645 <li>integrated the SGML DocBook support in xmllint</li>
646 <li>changed the nanoftp anonymous login passwd</li>
647 <li>some I/O cleanup and a couple of interfaces for Perl wrapper</li>
648 <li>general bug fixes</li>
649 <li>updated xmllint man page by John Fleck</li>
650 <li>some VMS and Windows updates</li>
651</ul>
652
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]653<h3>2.4.6: Oct 10 2001</h3>
654<ul>
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]655 <li>added an updated man pages by John Fleck</li>
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]656 <li>portability and configure fixes</li>
657 <li>an infinite loop on the HTML parser was removed (William)</li>
658 <li>Windows makefile patches from Igor</li>
659 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
660 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
661</ul>
662
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]663<h3>2.4.5: Sep 14 2001</h3>
664<ul>
665 <li>Remove a few annoying bugs in 2.4.4</li>
666 <li>forces the HTML serializer to output decimal charrefs since some
667 version of Netscape can't handle hexadecimal ones</li>
668</ul>
669
670<h3>1.8.16: Sep 14 2001</h3>
671<ul>
672 <li>maintenance release of the old libxml1 branch, couple of bug and
673 portability fixes</li>
674</ul>
675
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]676<h3>2.4.4: Sep 12 2001</h3>
677<ul>
678 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
679 Catalog</li>
680 <li>a few bug fixes and some portability changes</li>
681 <li>some documentation cleanups</li>
682</ul>
683
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]684<h3>2.4.3: Aug 23 2001</h3>
685<ul>
686 <li>XML Catalog support see the doc</li>
687 <li>New NaN/Infinity floating point code</li>
688 <li>A few bug fixes</li>
689</ul>
690
691<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]692<ul>
693 <li>adds xmlLineNumbersDefault() to control line number generation</li>
694 <li>lot of bug fixes</li>
695 <li>the Microsoft MSC projects files shuld now be up to date</li>
696 <li>inheritance of namespaces from DTD defaulted attributes</li>
697 <li>fixes a serious potential security bug</li>
698 <li>added a --format option to xmllint</li>
699</ul>
700
701<h3>2.4.1: July 24 2001</h3>
702<ul>
703 <li>possibility to keep line numbers in the tree</li>
704 <li>some computation NaN fixes</li>
705 <li>extension of the XPath API</li>
706 <li>cleanup for alpha and ia64 targets</li>
707 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]708</ul>
709
710<h3>2.4.0: July 10 2001</h3>
711<ul>
712 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
713 <li>Fixed XML Base implementation, added a coupel of examples to the
714 regression tests</li>
715 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]716</ul>
717
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]718<h3>2.3.14: July 5 2001</h3>
719<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]720 <li>fixed some entities problems and reduce mem requirement when
721 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]722 <li>lots of improvements in the XPath queries interpreter can be
723 substancially faster</li>
724 <li>Makefiles and configure cleanups</li>
725 <li>Fixes to XPath variable eval, and compare on empty node set</li>
726 <li>HTML tag closing bug fixed</li>
727 <li>Fixed an URI reference computating problem when validating</li>
728</ul>
729
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]730<h3>2.3.13: June 28 2001</h3>
731<ul>
732 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
733 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
734</ul>
735
736<h3>1.8.14: June 28 2001</h3>
737<ul>
738 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
739 <li>Small Makefile fix</li>
740</ul>
741
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]742<h3>2.3.12: June 26 2001</h3>
743<ul>
744 <li>lots of cleanup</li>
745 <li>a couple of validation fix</li>
746 <li>fixed line number counting</li>
747 <li>fixed serious problems in the XInclude processing</li>
748 <li>added support for UTF8 BOM at beginning of entities</li>
749 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
750 miscompile uri.c (William), Thomas Leitner provided a fix for the
751 optimizer on Tru64</li>
752 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
753 compilation on Windows MSC</li>
754 <li>update of libxml-doc.el (Felix Natter)</li>
755 <li>fixed 2 bugs in URI normalization code</li>
756</ul>
757
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]758<h3>2.3.11: June 17 2001</h3>
759<ul>
760 <li>updates to trio, Makefiles and configure should fix some portability
761 problems (alpha)</li>
762 <li>fixed some HTML serialization problems (pre, script, and block/inline
763 handling), added encoding aware APIs, cleanup of this code</li>
764 <li>added xmlHasNsProp()</li>
765 <li>implemented a specific PI for encoding support in the DocBook SGML
766 parser</li>
767 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
768 node selection)</li>
769 <li>fixed a performance problem and an error in the validation code</li>
770 <li>fixed XInclude routine to implement the recursive behaviour</li>
771 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
772 <li>added --version to xmllint for bug reports</li>
773</ul>
774
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]775<h3>2.3.10: June 1 2001</h3>
776<ul>
777 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]778 <li>a number of reported bugs got fixed, in XPath, iconv detection,
779 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]780 <li>XPath string function should now handle unicode correctly</li>
781</ul>
782
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]783<h3>2.3.9: May 19 2001</h3>
784
785<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
786<ul>
787 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
788 <li>some serious speed optimisation again</li>
789 <li>some documentation cleanups</li>
790 <li>trying to get better linking on solaris (-R)</li>
791 <li>XPath API cleanup from Thomas Broyer</li>
792 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
793 xmlValidGetValidElements()</li>
794 <li>Added an INSTALL file</li>
795 <li>Attribute removal added to API: #54433</li>
796 <li>added a basic support for SGML catalogs</li>
797 <li>fixed xmlKeepBlanksDefault(0) API</li>
798 <li>bugfix in xmlNodeGetLang()</li>
799 <li>fixed a small configure portability problem</li>
800 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
801</ul>
802
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]803<h3>1.8.13: May 14 2001</h3>
804<ul>
805 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
806</ul>
807
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]808<h3>2.3.8: May 3 2001</h3>
809<ul>
810 <li>Integrated an SGML DocBook parser for the Gnome project</li>
811 <li>Fixed a few things in the HTML parser</li>
812 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
813 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]814 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
815 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]816 <li>incorporated more Windows cleanup</li>
817 <li>added xmlSaveFormatFile()</li>
818 <li>fixed problems in copying nodes with entities references (gdome)</li>
819 <li>removed some troubles surrounding the new validation module</li>
820</ul>
821
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]822<h3>2.3.7: April 22 2001</h3>
823<ul>
824 <li>lots of small bug fixes, corrected XPointer</li>
825 <li>Non determinist content model validation support</li>
826 <li>added xmlDocCopyNode for gdome2</li>
827 <li>revamped the way the HTML parser handles end of tags</li>
828 <li>XPath: corrctions of namespacessupport and number formatting</li>
829 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
830 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
831 <li>Improved validation speed sensible for DocBook</li>
832 <li>fixed a big bug with ID declared in external parsed entities</li>
833 <li>portability fixes, update of Trio from Bjorn Reese</li>
834</ul>
835
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]836<h3>2.3.6: April 8 2001</h3>
837<ul>
838 <li>Code cleanup using extreme gcc compiler warning options, found and
839 cleared half a dozen potential problem</li>
840 <li>the Eazel team found an XML parser bug</li>
841 <li>cleaned up the user of some of the string formatting function. used the
842 trio library code to provide the one needed when the platform is missing
843 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]844 <li>xpath: removed a memory leak and fixed the predicate evaluation
845 problem, extended the testsuite and cleaned up the result. XPointer seems
846 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]847</ul>
848
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]849<h3>2.3.5: Mar 23 2001</h3>
850<ul>
851 <li>Biggest change is separate parsing and evaluation of XPath expressions,
852 there is some new APIs for this too</li>
853 <li>included a number of bug fixes(XML push parser, 51876, notations,
854 52299)</li>
855 <li>Fixed some portability issues</li>
856</ul>
857
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]858<h3>2.3.4: Mar 10 2001</h3>
859<ul>
860 <li>Fixed bugs #51860 and #51861</li>
861 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
862 size to be application tunable.</li>
863 <li>Some cleanup in the validation code, still a bug left and this part
864 should probably be rewritten to support ambiguous content model :-\</li>
865 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
866 parser</li>
867 <li>Fixed another bug in xmlNodeGetContent()</li>
868 <li>Bjorn fixed XPath node collection and Number formatting</li>
869 <li>Fixed a loop reported in the HTML parsing</li>
870 <li>blank space are reported even if the Dtd content model proves that they
871 are formatting spaces, this is for XmL conformance</li>
872</ul>
873
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]874<h3>2.3.3: Mar 1 2001</h3>
875<ul>
876 <li>small change in XPath for XSLT</li>
877 <li>documentation cleanups</li>
878 <li>fix in validation by Gary Pennington</li>
879 <li>serious parsing performances improvements</li>
880</ul>
881
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]882<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]883<ul>
884 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
885 <li>fixed a Dtd parsing bug</li>
886 <li>fixed a bug in xmlNodeGetContent</li>
887 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
888</ul>
889
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]890<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]891<ul>
892 <li>some XPath and HTML bug fixes for XSLT</li>
893 <li>small extension of the hash table interfaces for DOM gdome2
894 implementation</li>
895 <li>A few bug fixes</li>
896</ul>
897
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]898<h3>2.3.0: Feb 8 2001 (2.2.12 was on 25 Jan but I didn't kept track)</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]899<ul>
900 <li>Lots of XPath bug fixes</li>
901 <li>Add a mode with Dtd lookup but without validation error reporting for
902 XSLT</li>
903 <li>Add support for text node without escaping (XSLT)</li>
904 <li>bug fixes for xmlCheckFilename</li>
905 <li>validation code bug fixes from Gary Pennington</li>
906 <li>Patch from Paul D. Smith correcting URI path normalization</li>
907 <li>Patch to allow simultaneous install of libxml-devel and
908 libxml2-devel</li>
909 <li>the example Makefile is now fixed</li>
910 <li>added HTML to the RPM packages</li>
911 <li>tree copying bugfixes</li>
912 <li>updates to Windows makefiles</li>
913 <li>optimisation patch from Bjorn Reese</li>
914</ul>
915
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]916<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]917<ul>
918 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
919 <li>added htmlHandleOmittedElem()</li>
920 <li>Applied Bjorn Reese's IPV6 first patch</li>
921 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]922 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]923</ul>
924
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]925<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]926<ul>
927 <li>Fix the Windows problems of 2.2.8</li>
928 <li>integrate OpenVMS patches</li>
929 <li>better handling of some nasty HTML input</li>
930 <li>Improved the XPointer implementation</li>
931 <li>integrate a number of provided patches</li>
932</ul>
933
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]934<h3>2.2.9: Nov 25 2000</h3>
935<ul>
936 <li>erroneous release :-(</li>
937</ul>
938
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]939<h3>2.2.8: Nov 13 2000</h3>
940<ul>
941 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
942 support</li>
943 <li>Patch in conditional section handling</li>
944 <li>updated MS compiler project</li>
945 <li>fixed some XPath problems</li>
946 <li>added an URI escaping function</li>
947 <li>some other bug fixes</li>
948</ul>
949
950<h3>2.2.7: Oct 31 2000</h3>
951<ul>
952 <li>added message redirection</li>
953 <li>XPath improvements (thanks TOM !)</li>
954 <li>xmlIOParseDTD() added</li>
955 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
956 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
957</ul>
958
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]959<h3>2.2.6: Oct 25 2000:</h3>
960<ul>
961 <li>Added an hash table module, migrated a number of internal structure to
962 those</li>
963 <li>Fixed a posteriori validation problems</li>
964 <li>HTTP module cleanups</li>
965 <li>HTML parser improvements (tag errors, script/style handling, attribute
966 normalization)</li>
967 <li>coalescing of adjacent text nodes</li>
968 <li>couple of XPath bug fixes, exported the internal API</li>
969</ul>
970
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]971<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]972<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]973 <li>XPointer implementation and testsuite</li>
974 <li>Lot of XPath fixes, added variable and functions registration, more
975 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]976 <li>Portability fixes, lots of enhancements toward an easy Windows build
977 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]978 <li>Late validation fixes</li>
979 <li>Integrated a lot of contributed patches</li>
980 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]981 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]982</ul>
983
984<h3>2.2.4: Oct 1 2000:</h3>
985<ul>
986 <li>main XPath problem fixed</li>
987 <li>Integrated portability patches for Windows</li>
988 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]989</ul>
990
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]991<h3>2.2.3: Sep 17 2000</h3>
992<ul>
993 <li>bug fixes</li>
994 <li>cleanup of entity handling code</li>
995 <li>overall review of all loops in the parsers, all sprintf usage has been
996 checked too</li>
997 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
998 works smoothly now.</li>
999</ul>
1000
1001<h3>1.8.10: Sep 6 2000</h3>
1002<ul>
1003 <li>bug fix release for some Gnome projects</li>
1004</ul>
1005
1006<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1007<ul>
1008 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]1009 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]1010</ul>
1011
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1012<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1013<ul>
1014 <li>a purely bug fixes release</li>
1015 <li>fixed an encoding support problem when parsing from a memory block</li>
1016 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1017 <li>removed a bug in the function allowing to override the memory
1018 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]1019</ul>
1020
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]1021<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]1022<ul>
1023 <li>applied a lot of portability fixes</li>
1024 <li>better encoding support/cleanup and saving (content is now always
1025 encoded in UTF-8)</li>
1026 <li>the HTML parser now correctly handles encodings</li>
1027 <li>added xmlHasProp()</li>
1028 <li>fixed a serious problem with &amp;#38;</li>
1029 <li>propagated the fix to FTP client</li>
1030 <li>cleanup, bugfixes, etc ...</li>
1031 <li>Added a page about <a href="encoding.html">libxml Internationalization
1032 support</a></li>
1033</ul>
1034
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1035<h3>1.8.9: July 9 2000</h3>
1036<ul>
1037 <li>fixed the spec the RPMs should be better</li>
1038 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
1039 rpmfind users problem</li>
1040</ul>
1041
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]1042<h3>2.1.1: July 1 2000</h3>
1043<ul>
1044 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
1045 <li>improvements on the HTML parser</li>
1046</ul>
1047
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]1048<h3>2.1.0 and 1.8.8: June 29 2000</h3>
1049<ul>
1050 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
1051 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
1052 about &amp;#38; charref parsing</li>
1053 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
1054 also contains numerous fixes and enhancements:
1055 <ul>
1056 <li>added xmlStopParser() to stop parsing</li>
1057 <li>improved a lot parsing speed when there is large CDATA blocs</li>
1058 <li>includes XPath patches provided by Picdar Technology</li>
1059 <li>tried to fix as much as possible DtD validation and namespace
1060 related problems</li>
1061 <li>output to a given encoding has been added/tested</li>
1062 <li>lot of various fixes</li>
1063 </ul>
1064 </li>
1065</ul>
1066
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1067<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1068<ul>
1069 <li>First public release of libxml2. If you are using libxml, it's a good
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1070 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
1071 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
1072 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1073 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1074 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1075 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1076 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1077 <pre>#include "xxx.h"</pre>
1078 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]1079 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
1080 <li>the memory allocation routines used by libxml can now be overloaded
1081 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1082 <li>The previously CVS only tool tester has been renamed
1083 <strong>xmllint</strong> and is now installed as part of the libxml2
1084 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]1085 <li>The I/O interface has been revamped. There is now ways to plug in
1086 specific I/O modules, either at the URI scheme detection level using
1087 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1088 parser context using xmlCreateIOParserCtxt()</li>
1089 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1090 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1091 <li>a number of optional features of libxml can now be excluded at
1092 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1093</ul>
1094
1095<h3>2.0.0beta: Mar 14 2000</h3>
1096<ul>
1097 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1098 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1099 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1100 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1101 <li>This version is now the head in the Gnome CVS base, the old one is
1102 available under the tag LIB_XML_1_X</li>
1103 <li>This includes a very large set of changes. Froma programmatic point of
1104 view applications should not have to be modified too much, check the <a
1105 href="upgrade.html">upgrade page</a></li>
1106 <li>Some interfaces may changes (especially a bit about encoding).</li>
1107 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1108 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1109 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1110 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1111 <li>Better handling of entities, especially well formedness checking
1112 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1113 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1114 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1115 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1116 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1117 </ul>
1118 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1119 <li>Serious progress were made toward compliance, <a
1120 href="conf/result.html">here are the result of the test</a> against the
1121 OASIS testsuite (except the japanese tests since I don't support that
1122 encoding yet). This URL is rebuilt every couple of hours using the CVS
1123 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1124</ul>
1125
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1126<h3>1.8.7: Mar 6 2000</h3>
1127<ul>
1128 <li>This is a bug fix release:</li>
1129 <li>It is possible to disable the ignorable blanks heuristic used by
1130 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1131 that for adherence to XML spec, this behaviour will be disabled by
1132 default in 2.x . The same function will allow to keep compatibility for
1133 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1134 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1135 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1136 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1137 compilation on some platforms has been fixed</li>
1138 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1139 URIs</li>
1140</ul>
1141
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1142<h3>1.8.6: Jan 31 2000</h3>
1143<ul>
1144 <li>added a nanoFTP transport module, debugged until the new version of <a
1145 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1146 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1147</ul>
1148
1149<h3>1.8.5: Jan 21 2000</h3>
1150<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1151 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1152 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1153 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1154 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1155 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1156 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1157 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1158 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1159</ul>
1160
1161<h3>1.8.4: Jan 13 2000</h3>
1162<ul>
1163 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1164 <li>all exit() call should have been removed from libxml</li>
1165 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1166 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1167</ul>
1168
1169<h3>1.8.3: Jan 5 2000</h3>
1170<ul>
1171 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1172 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1173 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1174 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1175 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1176 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1177 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1178 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1179 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1180</ul>
1181
1182<h3>1.8.2: Dec 21 1999</h3>
1183<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1184 <li>I got another problem with includes and C++, I hope this issue is fixed
1185 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1186 <li>Added a few tree modification functions: xmlReplaceNode,
1187 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1188 xmlDocSetRootElement</li>
1189 <li>Tried to improve the HTML output with help from <a
1190 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1191</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1192
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1193<h3>1.8.1: Dec 18 1999</h3>
1194<ul>
1195 <li>various patches to avoid troubles when using libxml with C++ compilers
1196 the "namespace" keyword and C escaping in include files</li>
1197 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1198 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1199 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1200 <li>fixed a posteriori validation (validation after parsing, or by using a
1201 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1202 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1203</ul>
1204
1205<h3>1.8.0: Dec 12 1999</h3>
1206<ul>
1207 <li>cleanup, especially memory wise</li>
1208 <li>the parser should be more reliable, especially the HTML one, it should
1209 not crash, whatever the input !</li>
1210 <li>Integrated various patches, especially a speedup improvement for large
1211 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1212 configure with --with-buffers to enable them.</li>
1213 <li>attribute normalization, oops should have been added long ago !</li>
1214 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1215 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1216</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1217
1218<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1219<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1220 <li>Lots of HTML improvement</li>
1221 <li>Fixed some errors when saving both XML and HTML</li>
1222 <li>More examples, the regression tests should now look clean</li>
1223 <li>Fixed a bug with contiguous charref</li>
1224</ul>
1225
1226<h3>1.7.3: Sep 29 1999</h3>
1227<ul>
1228 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1229 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1230 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1231</ul>
1232
1233<h3>1.7.1: Sep 24 1999</h3>
1234<ul>
1235 <li>The basic type for strings manipulated by libxml has been renamed in
1236 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1237 is that CHAR was conflicting with a predefined type on Windows. However
1238 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1239 <strong>#define </strong>.</li>
1240 <li>Changed another error : the use of a structure field called errno, and
1241 leading to troubles on platforms where it's a macro</li>
1242</ul>
1243
1244<h3>1.7.0: sep 23 1999</h3>
1245<ul>
1246 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1247 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1248 <li>Added an errno to report errors by another mean than a simple printf
1249 like callback</li>
1250 <li>Finished ID/IDREF support and checking when validation</li>
1251 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1252 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1253 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1254 implementation</li>
1255 <li>Added an HTML parser front-end</li>
1256</ul>
1257
1258<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1259
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1260<p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1261markup-based structured documents. Here is <a name="example">an example XML
1262document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1263<pre>&lt;?xml version="1.0"?&gt;
1264&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1265 &lt;head&gt;
1266 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1267 &lt;/head&gt;
1268 &lt;chapter&gt;
1269 &lt;title&gt;The Linux adventure&lt;/title&gt;
1270 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1271 &lt;image href="linus.gif"/&gt;
1272 &lt;p&gt;...&lt;/p&gt;
1273 &lt;/chapter&gt;
1274&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1275
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1276<p>The first line specifies that it's an XML document and gives useful
1277information about its encoding. Then the document is a text format whose
1278structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1279to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1280(no content), a single tag can serve as both the opening and closing tag if
1281it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1282that, for example, the image tag has no content (just an attribute) and is
1283closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1284
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1285<p>XML can be applied sucessfully to a wide range of uses, from long term
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1286structured document maintenance (where it follows the steps of SGML) to
1287simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1288spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1289it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1290
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1291<h2><a name="XSLT">XSLT</a></h2>
1292
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1293<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1294
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1295<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1296language for transforming XML documents into other XML documents (or
1297HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1298
1299<p>A separate library called libxslt is being built on top of libxml2. This
1300module "libxslt" can be found in the Gnome CVS base too.</p>
1301
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1302<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1303href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1304supported and the progresses on the <a
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1305href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog"
1306name="Changelog">Changelog</a></p>
1307
1308<h2><a name="Python">Python and bindings</a></h2>
1309
1310<p>There is a number of language bindings and wrappers available for libxml2,
1311the list below is not exhaustive. Please contact the <a
1312href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
1313(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
1314order to get updates to this list or to discuss the specific topic of libxml2
1315or libxslt wrappers or bindings:</p>
1316<ul>
1317 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
1318 provides a C++ wrapper for libxml:<br>
1319 Website: <a
1320 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
1321 Download: <a
1322 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
1323 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
1324 based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
1325 <li><a
1326 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
1327 Sergeant</a>
1328 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
1329 wrapper for libxml2/libxslt as part of the <a
1330 href="http://axkit.com/">AxKit XML application server</a></li>
1331 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
1332 provides and earlier version of the libxml/libxslt <a
1333 href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
1334 <li>Petr Kozelka provides <a
1335 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
1336 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
1337 <li>Wai-Sun "Squidster" Chia provides <a
1338 href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
1339 libxml2 bindings are also available in Ruby through the <a
1340 href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
1341 maintained by Tobias Peters.</li>
Daniel Veillardb9e469a2002-02-21 12:08:42 +0000[diff] [blame]1342 <li>Steve Ball and contributors maintains
1343 <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
1344 Tcl</a>
1345 <li>There is support for libxml2 in the DOM module of PHP.
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1346</ul>
1347
1348<p>The distribution includes a set of Python bindings, which are garanteed to
1349be maintained as part of the library in the future, though the Python
1350interface have not yet reached the maturity of the C API. The distribution
1351includes a set of examples and regression tests for the python bindings in
1352the <code>python/tests</code> directory. Here are some excepts from those
1353tests:</p>
1354
1355<h3>tst.py:</h3>
1356
1357<p>This is a basic test of the file interface and DOM navigation:</p>
1358<pre>import libxml2
1359
1360doc = libxml2.parseFile("tst.xml")
1361if doc.name != "tst.xml":
1362 print "doc.name failed"
1363 sys.exit(1)
1364root = doc.children
1365if root.name != "doc":
1366 print "root.name failed"
1367 sys.exit(1)
1368child = root.children
1369if child.name != "foo":
1370 print "child.name failed"
1371 sys.exit(1)
1372doc.freeDoc()</pre>
1373
1374<p>The Python module is called libxml2, parseFile is the equivalent of
1375xmlParseFile (most of the bindings are automatically generated, and the xml
1376prefix is removed and the casing convention are kept). All node seen at the
1377binding level share the same subset of accesors:</p>
1378<ul>
1379 <li><code>name</code>
1380 : returns the node name</li>
1381 <li><code>type</code>
1382 : returns a string indicating the node typ<code>e</code></li>
1383 <li><code>content</code>
1384 : returns the content of the node, it is based on xmlNodeGetContent() and
1385 hence is recursive.</li>
1386 <li><code>parent</code>
1387 , <code>children</code>, <code>last</code>, <code>next</code>,
1388 <code>prev</code>, <code>doc</code>, <code>properties</code>: pointing to
1389 the associated element in the tree, those may return None in case no such
1390 link exists.</li>
1391</ul>
1392
1393<p>Also note the need to explicitely deallocate documents with freeDoc() .
1394Reference counting for libxml2 trees would need quite a lot of work to
1395function properly, and rather than risk memory leaks if not implemented
1396correctly it sounds safer to have an explicit function to free a tree. The
1397wrapper python objects like doc, root or child are them automatically garbage
1398collected.</p>
1399
1400<h3>validate.py:</h3>
1401
1402<p>This test check the validation interfaces and redirection of error
1403messages:</p>
1404<pre>import libxml2
1405
1406#desactivate error messages from the validation
1407def noerr(ctx, str):
1408 pass
1409
1410libxml2.registerErrorHandler(noerr, None)
1411
1412ctxt = libxml2.createFileParserCtxt("invalid.xml")
1413ctxt.validate(1)
1414ctxt.parseDocument()
1415doc = ctxt.doc()
1416valid = ctxt.isValid()
1417doc.freeDoc()
1418if valid != 0:
1419 print "validity chec failed"</pre>
1420
1421<p>The first thing to notice is the call to registerErrorHandler(), it
1422defines a new error handler global to the library. It is used to avoid seeing
1423the error messages when trying to validate the invalid document.</p>
1424
1425<p>The main interest of that test is the creation of a parser context with
1426createFileParserCtxt() and how the behaviour can be changed before calling
1427parseDocument() . Similary the informations resulting from the parsing phase
1428are also available using context methods.</p>
1429
1430<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
1431C function interfaces in terms of objects method as much as possible. The
1432best to get a complete view of what methods are supported is to look at the
1433libxml2.py module containing all the wrappers.</p>
1434
1435<h3>push.py:</h3>
1436
1437<p>This test show how to activate the push parser interface:</p>
1438<pre>import libxml2
1439
1440ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
1441ctxt.parseChunk("/&gt;", 2, 1)
1442doc = ctxt.doc()
1443
1444doc.freeDoc()</pre>
1445
1446<p>The context is created with a speciall call based on the
1447xmlCreatePushParser() from the C library. The first argument is an optional
1448SAX callback object, then the initial set of data, the lenght and the name of
1449the resource in case URI-References need to be computed by the parser.</p>
1450
1451<p>Then the data are pushed using the parseChunk() method, the last call
1452setting the thrird argument terminate to 1.</p>
1453
1454<h3>pushSAX.py:</h3>
1455
1456<p>this test show the use of the event based parsing interfaces. In this case
1457the parser does not build a document, but provides callback information as
1458the parser makes progresses analyzing the data being provided:</p>
1459<pre>import libxml2
1460log = ""
1461
1462class callback:
1463 def startDocument(self):
1464 global log
1465 log = log + "startDocument:"
1466
1467 def endDocument(self):
1468 global log
1469 log = log + "endDocument:"
1470
1471 def startElement(self, tag, attrs):
1472 global log
1473 log = log + "startElement %s %s:" % (tag, attrs)
1474
1475 def endElement(self, tag):
1476 global log
1477 log = log + "endElement %s:" % (tag)
1478
1479 def characters(self, data):
1480 global log
1481 log = log + "characters: %s:" % (data)
1482
1483 def warning(self, msg):
1484 global log
1485 log = log + "warning: %s:" % (msg)
1486
1487 def error(self, msg):
1488 global log
1489 log = log + "error: %s:" % (msg)
1490
1491 def fatalError(self, msg):
1492 global log
1493 log = log + "fatalError: %s:" % (msg)
1494
1495handler = callback()
1496
1497ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
1498chunk = " url='tst'&gt;b"
1499ctxt.parseChunk(chunk, len(chunk), 0)
1500chunk = "ar&lt;/foo&gt;"
1501ctxt.parseChunk(chunk, len(chunk), 1)
1502
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame^]1503reference = "startDocument:startElement foo {'url': 'tst'}:" + \
1504 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]1505if log != reference:
1506 print "Error got: %s" % log
1507 print "Exprected: %s" % reference</pre>
1508
1509<p>The key object in that test is the handler, it provides a number of entry
1510points which can be called by the parser as it makes progresses to indicate
1511the information set obtained. The full set of callback is larger than what
1512the callback class in that specific example implements (see the SAX
1513definition for a complete list). The wrapper will only call those supplied by
1514the object when activated. The startElement receives the names of the element
1515and a dictionnary containing the attributes carried by this element.</p>
1516
1517<p>Also note that the reference string generated from the callback shows a
1518single character call even though the string "bar" is passed to the parser
1519from 2 different call to parseChunk()</p>
1520
1521<h3>xpath.py:</h3>
1522
1523<p>This is a basic test of XPath warppers support</p>
1524<pre>import libxml2
1525
1526doc = libxml2.parseFile("tst.xml")
1527ctxt = doc.xpathNewContext()
1528res = ctxt.xpathEval("//*")
1529if len(res) != 2:
1530 print "xpath query: wrong node set size"
1531 sys.exit(1)
1532if res[0].name != "doc" or res[1].name != "foo":
1533 print "xpath query: wrong node set value"
1534 sys.exit(1)
1535doc.freeDoc()
1536ctxt.xpathFreeContext()</pre>
1537
1538<p>This test parses a file, then create an XPath context to evaluate XPath
1539expression on it. The xpathEval() method execute an XPath query and returns
1540the result mapped in a Python way. String and numbers are natively converted,
1541and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
1542the document, the XPath context need to be freed explicitely, also not that
1543the result of the XPath query may point back to the document tree and hence
1544the document must be freed after the result of the query is used.</p>
1545
1546<h3>xpathext.py:</h3>
1547
1548<p>This test shows how to extend the XPath engine with functions written in
1549python:</p>
1550<pre>import libxml2
1551
1552def foo(ctx, x):
1553 return x + 1
1554
1555doc = libxml2.parseFile("tst.xml")
1556ctxt = doc.xpathNewContext()
1557libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
1558res = ctxt.xpathEval("foo(1)")
1559if res != 2:
1560 print "xpath extension failure"
1561doc.freeDoc()
1562ctxt.xpathFreeContext()</pre>
1563
1564<p>Note how the extension function is registered with the context (but that
1565part is not yet finalized, ths may change slightly in the future).</p>
1566
1567<h3>tstxpath.py:</h3>
1568
1569<p>This test is similar to the previousone but shows how the extension
1570function can access the XPath evaluation context:</p>
1571<pre>def foo(ctx, x):
1572 global called
1573
1574 #
1575 # test that access to the XPath evaluation contexts
1576 #
1577 pctxt = libxml2.xpathParserContext(_obj=ctx)
1578 ctxt = pctxt.context()
1579 called = ctxt.function()
1580 return x + 1</pre>
1581
1582<p>All the interfaces around the XPath parser(or rather evaluation) context
1583are not finalized, but it should be sufficient to do contextual work at the
1584evaluation point.</p>
1585
1586<h3>Memory debugging:</h3>
1587
1588<p>last but not least, all tests starts with the following prologue:</p>
1589<pre>#memory debug specific
1590libxml2.debugMemory(1)
1591</pre>
1592
1593<p>and ends with the following epilogue:</p>
1594<pre>#memory debug specific
1595libxml2.cleanupParser()
1596if libxml2.debugMemory(1) == 0:
1597 print "OK"
1598else:
1599 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
1600 libxml2.dumpMemory()</pre>
1601
1602<p>Those activate the memory debugging interface of libxml2 where all
1603alloacted block in the library are tracked. The prologue then cleans up the
1604library state and checks that all allocated memory has been freed. If not it
1605calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1606
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1607<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1608
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1609<p>Libxml is made of multiple components; some of them are optional, and most
1610of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1611<ul>
1612 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1613 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1614 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1615 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1616 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1617 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1618 <li>a SAX tree module to build an in-memory DOM representation</li>
1619 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1620 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1621 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1622 (optional)</li>
1623 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1624</ul>
1625
1626<p>Graphically this gives the following:</p>
1627
1628<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1629
1630<p></p>
1631
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1632<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1633
1634<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1635returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1636<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1637as the file name, the document type, and a <strong>children</strong> pointer
1638which is the root of the document (or more exactly the first child under the
1639root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1640chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1641relationship. An xmlNode can also carry properties (a chain of xmlAttr
1642structures). An attribute may have a value which is a list of TEXT or
1643ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1644
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1645<p>Here is an example (erroneous with respect to the XML spec since there
1646should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1647
1648<p><img src="structure.gif" alt=" structure.gif "></p>
1649
1650<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1651called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1652prints them back as parsed. This is useful for detecting errors both in XML
1653code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1654which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1655result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1656<pre>DOCUMENT
1657version=1.0
1658standalone=true
1659 ELEMENT EXAMPLE
1660 ATTRIBUTE prop1
1661 TEXT
1662 content=gnome is great
1663 ATTRIBUTE prop2
1664 ENTITY_REF
1665 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1666 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1667 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1668 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1669 TEXT
1670 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1671 ELEMENT chapter
1672 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1673 TEXT
1674 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1675 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1676 TEXT
1677 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1678 ELEMENT image
1679 ATTRIBUTE href
1680 TEXT
1681 content=linus.gif
1682 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1683 TEXT
1684 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1685
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1686<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1687
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1688<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1689
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1690<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1691memory. In that case (and if you don't expect to save back the XML document
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1692loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1693a <strong>callback-based interface</strong> to the parser. Before parsing,
1694the application layer registers a customized set of callbacks which are
1695called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1696
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1697<p>To get more detailed step-by-step guidance on using the SAX interface of
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1698libxml, see the <a
1699href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1700documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1701Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1702
1703<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1704program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1705binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1706distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1707testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1708<pre>SAX.setDocumentLocator()
1709SAX.startDocument()
1710SAX.getEntity(amp)
1711SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1712SAX.characters( , 3)
1713SAX.startElement(head)
1714SAX.characters( , 4)
1715SAX.startElement(title)
1716SAX.characters(Welcome to Gnome, 16)
1717SAX.endElement(title)
1718SAX.characters( , 3)
1719SAX.endElement(head)
1720SAX.characters( , 3)
1721SAX.startElement(chapter)
1722SAX.characters( , 4)
1723SAX.startElement(title)
1724SAX.characters(The Linux adventure, 19)
1725SAX.endElement(title)
1726SAX.characters( , 4)
1727SAX.startElement(p)
1728SAX.characters(bla bla bla ..., 15)
1729SAX.endElement(p)
1730SAX.characters( , 4)
1731SAX.startElement(image, href='linus.gif')
1732SAX.endElement(image)
1733SAX.characters( , 4)
1734SAX.startElement(p)
1735SAX.characters(..., 3)
1736SAX.endElement(p)
1737SAX.characters( , 3)
1738SAX.endElement(chapter)
1739SAX.characters( , 1)
1740SAX.endElement(EXAMPLE)
1741SAX.endDocument()</pre>
1742
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1743<p>Most of the other interfaces of libxml are based on the DOM tree-building
1744facility, so nearly everything up to the end of this document presupposes the
1745use of the standard DOM tree build. Note that the DOM tree itself is built by
1746a set of registered default callbacks, without internal specific
1747interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1748
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1749<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1750
1751<p>Table of Content:</p>
1752<ol>
1753 <li><a href="#General5">General overview</a></li>
1754 <li><a href="#definition">The definition</a></li>
1755 <li><a href="#Simple">Simple rules</a>
1756 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1757 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1758 <li><a href="#Declaring">Declaring elements</a></li>
1759 <li><a href="#Declaring1">Declaring attributes</a></li>
1760 </ol>
1761 </li>
1762 <li><a href="#Some">Some examples</a></li>
1763 <li><a href="#validate">How to validate</a></li>
1764 <li><a href="#Other">Other resources</a></li>
1765</ol>
1766
1767<h3><a name="General5">General overview</a></h3>
1768
1769<p>Well what is validation and what is a DTD ?</p>
1770
1771<p>DTD is the acronym for Document Type Definition. This is a description of
1772the content for a familly of XML files. This is part of the XML 1.0
1773specification, and alows to describe and check that a given document instance
1774conforms to a set of rules detailing its structure and content.</p>
1775
1776<p>Validation is the process of checking a document against a DTD (more
1777generally against a set of construction rules).</p>
1778
1779<p>The validation process and building DTDs are the two most difficult parts
1780of the XML life cycle. Briefly a DTD defines all the possibles element to be
1781found within your document, what is the formal shape of your document tree
1782(by defining the allowed content of an element, either text, a regular
1783expression for the allowed list of children, or mixed content i.e. both text
1784and children). The DTD also defines the allowed attributes for all elements
1785and the types of the attributes.</p>
1786
1787<h3><a name="definition1">The definition</a></h3>
1788
1789<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1790href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1791Rev1</a>):</p>
1792<ul>
1793 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1794 elements</a></li>
1795 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1796 attributes</a></li>
1797</ul>
1798
1799<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1800ancient...</p>
1801
1802<h3><a name="Simple1">Simple rules</a></h3>
1803
1804<p>Writing DTD can be done in multiple ways, the rules to build them if you
1805need something fixed or something which can evolve over time can be radically
1806different. Really complex DTD like Docbook ones are flexible but quite harder
1807to design. I will just focuse on DTDs for a formats with a fixed simple
1808structure. It is just a set of basic rules, and definitely not exhaustive nor
1809useable for complex DTD design.</p>
1810
1811<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1812
1813<p>Assuming the top element of the document is <code>spec</code> and the dtd
1814is placed in the file <code>mydtd</code> in the subdirectory
1815<code>dtds</code> of the directory from where the document were loaded:</p>
1816
1817<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1818
1819<p>Notes:</p>
1820<ul>
1821 <li>the system string is actually an URI-Reference (as defined in <a
1822 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1823 full URL string indicating the location of your DTD on the Web, this is a
1824 really good thing to do if you want others to validate your document</li>
1825 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1826 magic string) so that the DTd is looked up in catalogs on the client side
1827 without having to locate it on the web</li>
1828 <li>a dtd contains a set of elements and attributes declarations, but they
1829 don't define what the root of the document should be. This is explicitely
1830 told to the parser/validator as the first element of the
1831 <code>DOCTYPE</code> declaration.</li>
1832</ul>
1833
1834<h4><a name="Declaring2">Declaring elements</a>:</h4>
1835
1836<p>The following declares an element <code>spec</code>:</p>
1837
1838<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1839
1840<p>it also expresses that the spec element contains one <code>front</code>,
1841one <code>body</code> and one optionnal <code>back</code> children elements
1842in this order. The declaration of one element of the structure and its
1843content are done in a single declaration. Similary the following declares
1844<code>div1</code> elements:</p>
1845
Daniel Veillard51737272002-01-23 23:10:38 +0000[diff] [blame]1846<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2?)&gt;</code></p>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1847
1848<p>means div1 contains one <code>head</code> then a series of optional
1849<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1850optional <code>div2</code>. And last but not least an element can contain
1851text:</p>
1852
1853<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1854
1855<p><code>b</code> contains text or being of mixed content (text and elements
1856in no particular order):</p>
1857
1858<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1859
1860<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1861<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1862order.</p>
1863
1864<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1865
1866<p>again the attributes declaration includes their content definition:</p>
1867
1868<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1869
1870<p>means that the element <code>termdef</code> can have a <code>name</code>
1871attribute containing text (<code>CDATA</code>) and which is optionnal
1872(<code>#IMPLIED</code>). The attribute value can also be defined within a
1873set:</p>
1874
1875<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1876"ordered"&gt;</code></p>
1877
1878<p>means <code>list</code> element have a <code>type</code> attribute with 3
1879allowed values "bullets", "ordered" or "glossary" and which default to
1880"ordered" if the attribute is not explicitely specified.</p>
1881
1882<p>The content type of an attribute can be text (<code>CDATA</code>),
1883anchor/reference/references
1884(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1885(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1886(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1887<code>chapter</code> element can have an optional <code>id</code> attribute
1888of type <code>ID</code>, usable for reference from attribute of type
1889IDREF:</p>
1890
1891<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1892
1893<p>The last value of an attribute definition can be <code>#REQUIRED
1894</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1895meaning that it is optional, or the default value (possibly prefixed by
1896<code>#FIXED</code> if it is the only allowed).</p>
1897
1898<p>Notes:</p>
1899<ul>
1900 <li>usually the attributes pertaining to a given element are declared in a
1901 single expression, but it is just a convention adopted by a lot of DTD
1902 writers:
1903 <pre>&lt;!ATTLIST termdef
1904 id ID #REQUIRED
1905 name CDATA #IMPLIED&gt;</pre>
1906 <p>The previous construct defines both <code>id</code> and
1907 <code>name</code> attributes for the element <code>termdef</code></p>
1908 </li>
1909</ul>
1910
1911<h3><a name="Some1">Some examples</a></h3>
1912
1913<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1914contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1915example shows an XML file where the simple DTD is directly included within
1916the document.</p>
1917
1918<h3><a name="validate1">How to validate</a></h3>
1919
1920<p>The simplest is to use the xmllint program comming with libxml. The
1921<code>--valid</code> option turn on validation of the files given as input,
1922for example the following validates a copy of the first revision of the XML
19231.0 specification:</p>
1924
1925<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1926
1927<p>the -- noout is used to not output the resulting tree.</p>
1928
1929<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1930a given DTD.</p>
1931
1932<p>Libxml exports an API to handle DTDs and validation, check the <a
1933href="http://xmlsoft.org/html/libxml-valid.html">associated
1934description</a>.</p>
1935
1936<h3><a name="Other1">Other resources</a></h3>
1937
1938<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1939will just list one for now, others pointers welcome:</p>
1940<ul>
1941 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1942</ul>
1943
1944<p>I suggest looking at the examples found under test/valid/dtd and any of
1945the large number of books available on XML. The dia example in test/valid
1946should be both simple and complete enough to allow you to build your own.</p>
1947
1948<p></p>
1949
1950<h2><a name="Memory">Memory Management</a></h2>
1951
1952<p>Table of Content:</p>
1953<ol>
1954 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1955 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1956 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1957 <li><a href="#Debugging">Debugging routines</a></li>
1958 <li><a href="#General4">General memory requirements</a></li>
1959</ol>
1960
1961<h3><a name="General3">General overview</a></h3>
1962
1963<p>The module <code><a
1964href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1965provides the interfaces to the libxml memory system:</p>
1966<ul>
1967 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1968 xmlMalloc() and xmlRealloc()</li>
1969 <li>those routines can be reallocated to a specific set of routine, by
1970 default the libc ones i.e. free(), malloc() and realloc()</li>
1971 <li>the xmlmemory.c module includes a set of debugging routine</li>
1972</ul>
1973
1974<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1975
1976<p>It is sometimes useful to not use the default memory allocator, either for
1977debugging, analysis or to implement a specific behaviour on memory management
1978(like on embedded systems). Two function calls are available to do so:</p>
1979<ul>
1980 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1981 which return the current set of functions in use by the parser</li>
1982 <li><a
1983 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1984 which allow to set up a new set of memory allocation functions</li>
1985</ul>
1986
1987<p>Of course a call to xmlMemSetup() should probably be done before calling
1988any other libxml routines (unless you are sure your allocations routines are
1989compatibles).</p>
1990
1991<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1992
1993<p>Libxml is not stateless, there is a few set of memory structures needing
1994allocation before the parser is fully functionnal (some encoding structures
1995for example). This also mean that once parsing is finished there is a tiny
1996amount of memory (a few hundred bytes) which can be recollected if you don't
1997reuse the parser immediately:</p>
1998<ul>
1999 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
2000 ()</a>
2001 is a centralized routine to free the parsing states. Note that it won't
2002 deallocate any produced tree if any (use the xmlFreeDoc() and related
2003 routines for this).</li>
2004 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
2005 ()</a>
2006 is the dual routine allowing to preallocate the parsing state which can
2007 be useful for example to avoid initialization reentrancy problems when
2008 using libxml in multithreaded applications</li>
2009</ul>
2010
2011<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
2012at the next invocation of parser routines, but be careful of the consequences
2013in multithreaded applications.</p>
2014
2015<h3><a name="Debugging">Debugging routines</a></h3>
2016
2017<p>When configured using --with-mem-debug flag (off by default), libxml uses
2018a set of memory allocation debugging routineskeeping track of all allocated
2019blocks and the location in the code where the routine was called. A couple of
2020other debugging routines allow to dump the memory allocated infos to a file
2021or call a specific routine when a given block number is allocated:</p>
2022<ul>
2023 <li><a
2024 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
2025 <a
2026 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
2027 and <a
2028 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
2029 are the memory debugging replacement allocation routines</li>
2030 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
2031 ()</a>
2032 dumps all the informations about the allocated memory block lefts in the
2033 <code>.memdump</code> file</li>
2034</ul>
2035
2036<p>When developping libxml memory debug is enabled, the tests programs call
2037xmlMemoryDump () and the "make test" regression tests will check for any
2038memory leak during the full regression test sequence, this helps a lot
2039ensuring that libxml does not leak memory and bullet proof memory
2040allocations use (some libc implementations are known to be far too permissive
2041resulting in major portability problems!).</p>
2042
2043<p>If the .memdump reports a leak, it displays the allocation function and
2044also tries to give some informations about the content and structure of the
2045allocated blocks left. This is sufficient in most cases to find the culprit,
2046but not always. Assuming the allocation problem is reproductible, it is
2047possible to find more easilly:</p>
2048<ol>
2049 <li>write down the block number xxxx not allocated</li>
2050 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
2051 <li>run the program under a debugger and set a breakpoint on
2052 xmlMallocBreakpoint() a specific function called when this precise block
2053 is allocated</li>
2054 <li>when the breakpoint is reached you can then do a fine analysis of the
2055 allocation an step to see the condition resulting in the missing
2056 deallocation.</li>
2057</ol>
2058
2059<p>I used to use a commercial tool to debug libxml memory problems but after
2060noticing that it was not detecting memory leaks that simple mechanism was
2061used and proved extremely efficient until now.</p>
2062
2063<h3><a name="General4">General memory requirements</a></h3>
2064
2065<p>How much libxml memory require ? It's hard to tell in average it depends
2066of a number of things:</p>
2067<ul>
2068 <li>the parser itself should work in a fixed amout of memory, except for
2069 information maintained about the stacks of names and entities locations.
2070 The I/O and encoding handlers will probably account for a few KBytes.
2071 This is true for both the XML and HTML parser (though the HTML parser
2072 need more state).</li>
2073 <li>If you are generating the DOM tree then memory requirements will grow
2074 nearly lineary with the size of the data. In general for a balanced
2075 textual document the internal memory requirement is about 4 times the
2076 size of the UTF8 serialization of this document (exmple the XML-1.0
2077 recommendation is a bit more of 150KBytes and takes 650KBytes of main
2078 memory when parsed). Validation will add a amount of memory required for
2079 maintaining the external Dtd state which should be linear with the
2080 complexity of the content model defined by the Dtd</li>
2081 <li>If you don't care about the advanced features of libxml like
2082 validation, DOM, XPath or XPointer, but really need to work fixed memory
2083 requirements, then the SAX interface should be used.</li>
2084</ul>
2085
2086<p></p>
2087
2088<h2><a name="Encodings">Encodings support</a></h2>
2089
2090<p>Table of Content:</p>
2091<ol>
2092 <li><a href="encoding.html#What">What does internationalization support
2093 mean ?</a></li>
2094 <li><a href="encoding.html#internal">The internal encoding, how and
2095 why</a></li>
2096 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
2097 <li><a href="encoding.html#Default">Default supported encodings</a></li>
2098 <li><a href="encoding.html#extend">How to extend the existing
2099 support</a></li>
2100</ol>
2101
2102<h3><a name="What">What does internationalization support mean ?</a></h3>
2103
2104<p>XML was designed from the start to allow the support of any character set
2105by using Unicode. Any conformant XML parser has to support the UTF-8 and
2106UTF-16 default encodings which can both express the full unicode ranges. UTF8
2107is a variable length encoding whose greatest point are to resuse the same
2108emcoding for ASCII and to save space for Western encodings, but it is a bit
2109more complex to handle in practice. UTF-16 use 2 bytes per characters (and
2110sometimes combines two pairs), it makes implementation easier, but looks a
2111bit overkill for Western languages encoding. Moreover the XML specification
2112allows document to be encoded in other encodings at the condition that they
2113are clearly labelled as such. For example the following is a wellformed XML
2114document encoded in ISO-8859 1 and using accentuated letter that we French
2115likes for both markup and content:</p>
2116<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2117&lt;très&gt;là&lt;/très&gt;</pre>
2118
2119<p>Having internationalization support in libxml means the foolowing:</p>
2120<ul>
2121 <li>the document is properly parsed</li>
2122 <li>informations about it's encoding are saved</li>
2123 <li>it can be modified</li>
2124 <li>it can be saved in its original encoding</li>
2125 <li>it can also be saved in another encoding supported by libxml (for
2126 example straight UTF8 or even an ASCII form)</li>
2127</ul>
2128
2129<p>Another very important point is that the whole libxml API, with the
2130exception of a few routines to read with a specific encoding or save to a
2131specific encoding, is completely agnostic about the original encoding of the
2132document.</p>
2133
2134<p>It should be noted too that the HTML parser embedded in libxml now obbey
2135the same rules too, the following document will be (as of 2.2.2) handled in
2136an internationalized fashion by libxml too:</p>
2137<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
2138 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
2139&lt;html lang="fr"&gt;
2140&lt;head&gt;
2141 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
2142&lt;/head&gt;
2143&lt;body&gt;
2144&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
2145&lt;/html&gt;</pre>
2146
2147<h3><a name="internal">The internal encoding, how and why</a></h3>
2148
2149<p>One of the core decision was to force all documents to be converted to a
2150default internal encoding, and that encoding to be UTF-8, here are the
2151rationale for those choices:</p>
2152<ul>
2153 <li>keeping the native encoding in the internal form would force the libxml
2154 users (or the code associated) to be fully aware of the encoding of the
2155 original document, for examples when adding a text node to a document,
2156 the content would have to be provided in the document encoding, i.e. the
2157 client code would have to check it before hand, make sure it's conformant
2158 to the encoding, etc ... Very hard in practice, though in some specific
2159 cases this may make sense.</li>
2160 <li>the second decision was which encoding. From the XML spec only UTF8 and
2161 UTF16 really makes sense as being the two only encodings for which there
2162 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
2163 considered an intelligent choice too since it's a direct Unicode mapping
2164 support. I selected UTF-8 on the basis of efficiency and compatibility
2165 with surrounding software:
2166 <ul>
2167 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
2168 more costly to import and export CPU wise) is also far more compact
2169 than UTF-16 (and UCS-4) for a majority of the documents I see it used
2170 for right now (RPM RDF catalogs, advogato data, various configuration
2171 file formats, etc.) and the key point for today's computer
2172 architecture is efficient uses of caches. If one nearly double the
2173 memory requirement to store the same amount of data, this will trash
2174 caches (main memory/external caches/internal caches) and my take is
2175 that this harms the system far more than the CPU requirements needed
2176 for the conversion to UTF-8</li>
2177 <li>Most of libxml version 1 users were using it with straight ASCII
2178 most of the time, doing the conversion with an internal encoding
2179 requiring all their code to be rewritten was a serious show-stopper
2180 for using UTF-16 or UCS-4.</li>
2181 <li>UTF-8 is being used as the de-facto internal encoding standard for
2182 related code like the <a href="http://www.pango.org/">pango</a>
2183 upcoming Gnome text widget, and a lot of Unix code (yep another place
2184 where Unix programmer base takes a different approach from Microsoft
2185 - they are using UTF-16)</li>
2186 </ul>
2187 </li>
2188</ul>
2189
2190<p>What does this mean in practice for the libxml user:</p>
2191<ul>
2192 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
2193 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
2194 is simply to append 0 byte, as usual.</li>
2195 <li>One just need to make sure that when using chars outside the ASCII set,
2196 the values has been properly converted to UTF-8</li>
2197</ul>
2198
2199<h3><a name="implemente">How is it implemented ?</a></h3>
2200
2201<p>Let's describe how all this works within libxml, basically the I18N
2202(internationalization) support get triggered only during I/O operation, i.e.
2203when reading a document or saving one. Let's look first at the reading
2204sequence:</p>
2205<ol>
2206 <li>when a document is processed, we usually don't know the encoding, a
2207 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
2208 ASCII range (0-0x7F) maps with ASCII</li>
2209 <li>the xml declaration if available is parsed, including the encoding
2210 declaration. At that point, if the autodetected encoding is different
2211 from the one declared a call to xmlSwitchEncoding() is issued.</li>
2212 <li>If there is no encoding declaration, then the input has to be in either
2213 UTF-8 or UTF-16, if it is not then at some point when processing the
2214 input, the converter/checker of UTF-8 form will raise an encoding error.
2215 You may end-up with a garbled document, or no document at all ! Example:
2216 <pre>~/XML -&gt; ./xmllint err.xml
2217err.xml:1: error: Input is not proper UTF-8, indicate encoding !
2218&lt;très&gt;là&lt;/très&gt;
2219 ^
2220err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
2221&lt;très&gt;là&lt;/très&gt;
2222 ^</pre>
2223 </li>
2224 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
2225 then search the default registered encoding converters for that encoding.
2226 If it's not within the default set and iconv() support has been compiled
2227 it, it will ask iconv for such an encoder. If this fails then the parser
2228 will report an error and stops processing:
2229 <pre>~/XML -&gt; ./xmllint err2.xml
2230err2.xml:1: error: Unsupported encoding UnsupportedEnc
2231&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
2232 ^</pre>
2233 </li>
2234 <li>From that point the encoder process progressingly the input (it is
2235 plugged as a front-end to the I/O module) for that entity. It captures
2236 and convert on-the-fly the document to be parsed to UTF-8. The parser
2237 itself just does UTF-8 checking of this input and process it
2238 transparently. The only difference is that the encoding information has
2239 been added to the parsing context (more precisely to the input
2240 corresponding to this entity).</li>
2241 <li>The result (when using DOM) is an internal form completely in UTF-8
2242 with just an encoding information on the document node.</li>
2243</ol>
2244
2245<p>Ok then what's happen when saving the document (assuming you
2246colllected/built an xmlDoc DOM like structure) ? It depends on the function
2247called, xmlSaveFile() will just try to save in the original encoding, while
2248xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
2249encoding:</p>
2250<ol>
2251 <li>if no encoding is given, libxml will look for an encoding value
2252 associated to the document and if it exists will try to save to that
2253 encoding,
2254 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
2255 </li>
2256 <li>so if an encoding was specified, either at the API level or on the
2257 document, libxml will again canonalize the encoding name, lookup for a
2258 converter in the registered set or through iconv. If not found the
2259 function will return an error code</li>
2260 <li>the converter is placed before the I/O buffer layer, as another kind of
2261 buffer, then libxml will simply push the UTF-8 serialization to through
2262 that buffer, which will then progressively be converted and pushed onto
2263 the I/O layer.</li>
2264 <li>It is possible that the converter code fails on some input, for example
2265 trying to push an UTF-8 encoded chinese character through the UTF-8 to
2266 ISO-8859-1 converter won't work. Since the encoders are progressive they
2267 will just report the error and the number of bytes converted, at that
2268 point libxml will decode the offending character, remove it from the
2269 buffer and replace it with the associated charRef encoding &amp;#123; and
2270 resume the convertion. This guarante that any document will be saved
2271 without losses (except for markup names where this is not legal, this is
2272 a problem in the current version, in pactice avoid using non-ascci
2273 characters for tags or attributes names @@). A special "ascii" encoding
2274 name is used to save documents to a pure ascii form can be used when
2275 portability is really crucial</li>
2276</ol>
2277
2278<p>Here is a few examples based on the same test document:</p>
2279<pre>~/XML -&gt; ./xmllint isolat1
2280&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
2281&lt;très&gt;là&lt;/très&gt;
2282~/XML -&gt; ./xmllint --encode UTF-8 isolat1
2283&lt;?xml version="1.0" encoding="UTF-8"?&gt;
2284&lt;très&gt;là  &lt;/très&gt;
2285~/XML -&gt; </pre>
2286
2287<p>The same processing is applied (and reuse most of the code) for HTML I18N
2288processing. Looking up and modifying the content encoding is a bit more
2289difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
2290so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
2291been provided. The parser also attempts to switch encoding on the fly when
2292detecting such a tag on input. Except for that the processing is the same
2293(and again reuses the same code).</p>
2294
2295<h3><a name="Default">Default supported encodings</a></h3>
2296
2297<p>libxml has a set of default converters for the following encodings
2298(located in encoding.c):</p>
2299<ol>
2300 <li>UTF-8 is supported by default (null handlers)</li>
2301 <li>UTF-16, both little and big endian</li>
2302 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
2303 <li>ASCII, useful mostly for saving</li>
2304 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
2305 predefined entities like &amp;copy; for the Copyright sign.</li>
2306</ol>
2307
2308<p>More over when compiled on an Unix platfor with iconv support the full set
2309of encodings supported by iconv can be instantly be used by libxml. On a
2310linux machine with glibc-2.1 the list of supported encodings and aliases fill
23113 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
2312various Japanese ones.</p>
2313
2314<h4>Encoding aliases</h4>
2315
2316<p>From 2.2.3, libxml has support to register encoding names aliases. The
2317goal is to be able to parse document whose encoding is supported but where
2318the name differs (for example from the default set of names accepted by
2319iconv). The following functions allow to register and handle new aliases for
2320existing encodings. Once registered libxml will automatically lookup the
2321aliases when handling a document:</p>
2322<ul>
2323 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
2324 <li>int xmlDelEncodingAlias(const char *alias);</li>
2325 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
2326 <li>void xmlCleanupEncodingAliases(void);</li>
2327</ul>
2328
2329<h3><a name="extend">How to extend the existing support</a></h3>
2330
2331<p>Well adding support for new encoding, or overriding one of the encoders
2332(assuming it is buggy) should not be hard, just write an input and output
2333conversion routines to/from UTF-8, and register them using
2334xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
2335called automatically if the parser(s) encounter such an encoding name
2336(register it uppercase, this will help). The description of the encoders,
2337their arguments and expected return values are described in the encoding.h
2338header.</p>
2339
2340<p>A quick note on the topic of subverting the parser to use a different
2341internal encoding than UTF-8, in some case people will absolutely want to
2342keep the internal encoding different, I think it's still possible (but the
2343encoding must be compliant with ASCII on the same subrange) though I didn't
2344tried it. The key is to override the default conversion routines (by
2345registering null encoders/decoders for your charsets), and bypass the UTF-8
2346checking of the parser by setting the parser context charset
2347(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
2348there is no guarantee taht this will work. You may also have some troubles
2349saving back.</p>
2350
2351<p>Basically proper I18N support is important, this requires at least
2352libxml-2.0.0, but a lot of features and corrections are really available only
2353starting 2.2.</p>
2354
2355<h2><a name="IO">I/O Interfaces</a></h2>
2356
2357<p>Table of Content:</p>
2358<ol>
2359 <li><a href="#General1">General overview</a></li>
2360 <li><a href="#basic">The basic buffer type</a></li>
2361 <li><a href="#Input">Input I/O handlers</a></li>
2362 <li><a href="#Output">Output I/O handlers</a></li>
2363 <li><a href="#entities">The entities loader</a></li>
2364 <li><a href="#Example2">Example of customized I/O</a></li>
2365</ol>
2366
2367<h3><a name="General1">General overview</a></h3>
2368
2369<p>The module <code><a
2370href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
2371the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
2372<ul>
2373 <li>Entities loader, this is a routine which tries to fetch the entities
2374 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
2375 don't look at the public identifier since libxml do not maintain a
2376 catalog. You can redefine you own entity loader by using
2377 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2378 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
2379 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2380 <li>Input I/O buffers which are a commodity structure used by the parser(s)
2381 input layer to handle fetching the informations to feed the parser. This
2382 provides buffering and is also a placeholder where the encoding
2383 convertors to UTF8 are piggy-backed.</li>
2384 <li>Output I/O buffers are similar to the Input ones and fulfill similar
2385 task but when generating a serialization from a tree.</li>
2386 <li>A mechanism to register sets of I/O callbacks and associate them with
2387 specific naming schemes like the protocol part of the URIs.
2388 <p>This affect the default I/O operations and allows to use specific I/O
2389 handlers for certain names.</p>
2390 </li>
2391</ul>
2392
2393<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2394example in the HTML parser is the following:</p>
2395<ol>
2396 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2397 the parsing context and the URI string.</li>
2398 <li>the URI string is checked against the existing registered handlers
2399 using their match() callback function, if the HTTP module was compiled
2400 in, it is registered and its match() function will succeeds</li>
2401 <li>the open() function of the handler is called and if successful will
2402 return an I/O Input buffer</li>
2403 <li>the parser will the start reading from this buffer and progressively
2404 fetch information from the resource, calling the read() function of the
2405 handler until the resource is exhausted</li>
2406 <li>if an encoding change is detected it will be installed on the input
2407 buffer, providing buffering and efficient use of the conversion
2408 routines</li>
2409 <li>once the parser has finished, the close() function of the handler is
2410 called once and the Input buffer and associed resources are
2411 deallocated.</li>
2412</ol>
2413
2414<p>The user defined callbacks are checked first to allow overriding of the
2415default libxml I/O routines.</p>
2416
2417<h3><a name="basic">The basic buffer type</a></h3>
2418
2419<p>All the buffer manipulation handling is done using the
2420<code>xmlBuffer</code> type define in <code><a
2421href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2422resizable memory buffer. The buffer allocation strategy can be selected to be
2423either best-fit or use an exponential doubling one (CPU vs. memory use
2424tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2425<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2426system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2427of functions allows to manipulate buffers with names starting with the
2428<code>xmlBuffer...</code> prefix.</p>
2429
2430<h3><a name="Input">Input I/O handlers</a></h3>
2431
2432<p>An Input I/O handler is a simple structure
2433<code>xmlParserInputBuffer</code> containing a context associated to the
2434resource (file descriptor, or pointer to a protocol handler), the read() and
2435close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2436encoding handler are also present to support charset conversion when
2437needed.</p>
2438
2439<h3><a name="Output">Output I/O handlers</a></h3>
2440
2441<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2442Input one except the callbacks are write() and close().</p>
2443
2444<h3><a name="entities">The entities loader</a></h3>
2445
2446<p>The entity loader resolves requests for new entities and create inputs for
2447the parser. Creating an input from a filename or an URI string is done
2448through the xmlNewInputFromFile() routine. The default entity loader do not
2449handle the PUBLIC identifier associated with an entity (if any). So it just
2450calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2451XML).</p>
2452
2453<p>If you want to hook up a catalog mechanism then you simply need to
2454override the default entity loader, here is an example:</p>
2455<pre>#include &lt;libxml/xmlIO.h&gt;
2456
2457xmlExternalEntityLoader defaultLoader = NULL;
2458
2459xmlParserInputPtr
2460xmlMyExternalEntityLoader(const char *URL, const char *ID,
2461 xmlParserCtxtPtr ctxt) {
2462 xmlParserInputPtr ret;
2463 const char *fileID = NULL;
2464 /* lookup for the fileID depending on ID */
2465
2466 ret = xmlNewInputFromFile(ctxt, fileID);
2467 if (ret != NULL)
2468 return(ret);
2469 if (defaultLoader != NULL)
2470 ret = defaultLoader(URL, ID, ctxt);
2471 return(ret);
2472}
2473
2474int main(..) {
2475 ...
2476
2477 /*
2478 * Install our own entity loader
2479 */
2480 defaultLoader = xmlGetExternalEntityLoader();
2481 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2482
2483 ...
2484}</pre>
2485
2486<h3><a name="Example2">Example of customized I/O</a></h3>
2487
2488<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2489real use case</a>, xmlDocDump() closes the FILE * passed by the application
2490and this was a problem. The <a
2491href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2492new output handler with the closing call deactivated:</p>
2493<ol>
2494 <li>First define a new I/O ouput allocator where the output don't close the
2495 file:
2496 <pre>xmlOutputBufferPtr
2497xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2498    xmlOutputBufferPtr ret;
2499    
2500    if (xmlOutputCallbackInitialized == 0)
2501        xmlRegisterDefaultOutputCallbacks();
2502
2503    if (file == NULL) return(NULL);
2504    ret = xmlAllocOutputBuffer(encoder);
2505    if (ret != NULL) {
2506        ret-&gt;context = file;
2507        ret-&gt;writecallback = xmlFileWrite;
2508        ret-&gt;closecallback = NULL; /* No close callback */
2509    }
2510    return(ret); <br>
2511
2512
2513
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2514
2515
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2516
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]2517
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]2518
Daniel Veillarded421aa2001-11-04 21:22:45 +0000[diff] [blame]2519
Daniel Veillard43d3f612001-11-10 11:57:23 +0000[diff] [blame]2520
Daniel Veillarda4871052001-11-26 13:19:48 +0000[diff] [blame]2521
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]2522
Daniel Veillardef90ba72001-12-07 14:24:22 +0000[diff] [blame]2523
Daniel Veillard9ae4b7a2001-12-13 14:24:09 +0000[diff] [blame]2524
Daniel Veillard845cce42002-01-09 11:51:37 +0000[diff] [blame]2525
Daniel Veillard744683d2002-01-14 17:30:20 +0000[diff] [blame]2526
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2527
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2528
Daniel Veillardb6c1e2f2002-02-08 14:52:52 +0000[diff] [blame]2529
Daniel Veillard397ff112002-02-11 18:27:20 +0000[diff] [blame]2530
Daniel Veillarde46182c2002-02-12 14:29:11 +0000[diff] [blame]2531
Daniel Veillard5f4b5992002-02-20 10:22:49 +0000[diff] [blame]2532
Daniel Veillard5b16f582002-02-20 11:38:46 +0000[diff] [blame]2533
Daniel Veillarda5393562002-02-20 11:40:49 +0000[diff] [blame]2534
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]2535
2536
2537
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2538} </pre>
2539 </li>
2540 <li>And then use it to save the document:
2541 <pre>FILE *f;
2542xmlOutputBufferPtr output;
2543xmlDocPtr doc;
2544int res;
2545
2546f = ...
2547doc = ....
2548
2549output = xmlOutputBufferCreateOwn(f, NULL);
2550res = xmlSaveFileTo(output, doc, NULL);
2551 </pre>
2552 </li>
2553</ol>
2554
2555<h2><a name="Catalog">Catalog support</a></h2>
2556
2557<p>Table of Content:</p>
2558<ol>
2559 <li><a href="General2">General overview</a></li>
2560 <li><a href="#definition">The definition</a></li>
2561 <li><a href="#Simple">Using catalogs</a></li>
2562 <li><a href="#Some">Some examples</a></li>
2563 <li><a href="#reference">How to tune catalog usage</a></li>
2564 <li><a href="#validate">How to debug catalog processing</a></li>
2565 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2566 <li><a href="#implemento">The implementor corner quick review of the
2567 API</a></li>
2568 <li><a href="#Other">Other resources</a></li>
2569</ol>
2570
2571<h3><a name="General2">General overview</a></h3>
2572
2573<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2574(a file or a remote resource) references another entity. The catalog lookup
2575is inserted between the moment the reference is recognized by the software
2576(XML parser, stylesheet processing, or even images referenced for inclusion
2577in a rendering) and the time where loading that resource is actually
2578started.</p>
2579
2580<p>It is basically used for 3 things:</p>
2581<ul>
2582 <li>mapping from "logical" names, the public identifiers and a more
2583 concrete name usable for download (and URI). For example it can associate
2584 the logical name
2585 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2586 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2587 downloaded</p>
2588 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2589 </li>
2590 <li>remapping from a given URL to another one, like an HTTP indirection
2591 saying that
2592 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2593 <p>should really be looked at</p>
2594 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2595 </li>
2596 <li>providing a local cache mechanism allowing to load the entities
2597 associated to public identifiers or remote resources, this is a really
2598 important feature for any significant deployment of XML or SGML since it
2599 allows to avoid the aleas and delays associated to fetching remote
2600 resources.</li>
2601</ul>
2602
2603<h3><a name="definition">The definitions</a></h3>
2604
2605<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2606<ul>
2607 <li>the older SGML catalogs, the official spec is SGML Open Technical
2608 Resolution TR9401:1997, but is better understood by reading <a
2609 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2610 James Clark. This is relatively old and not the preferred mode of
2611 operation of libxml.</li>
2612 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2613 Catalogs</a>
2614 is far more flexible, more recent, uses an XML syntax and should scale
2615 quite better. This is the default option of libxml.</li>
2616</ul>
2617
2618<p></p>
2619
2620<h3><a name="Simple">Using catalog</a></h3>
2621
2622<p>In a normal environment libxml will by default check the presence of a
2623catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2624the processing is completely transparent to the document user. To take a
2625concrete example, suppose you are authoring a DocBook document, this one
2626starts with the following DOCTYPE definition:</p>
2627<pre>&lt;?xml version='1.0'?&gt;
2628&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2629 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2630
2631<p>When validating the document with libxml, the catalog will be
2632automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2633DocBk XML V3.1.4//EN" and the system identifier
2634"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2635been installed on your system and the catalogs actually point to them, libxml
2636will fetch them from the local disk.</p>
2637
2638<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2639DOCTYPE example it's a really old version, but is fine as an example.</p>
2640
2641<p>Libxml will check the catalog each time that it is requested to load an
2642entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2643your system is correctly configured all the authoring phase and processing
2644should use only local files, even if your document stays portable because it
2645uses the canonical public and system ID, referencing the remote document.</p>
2646
2647<h3><a name="Some">Some examples:</a></h3>
2648
2649<p>Here is a couple of fragments from XML Catalogs used in libxml early
2650regression tests in <code>test/catalogs</code> :</p>
2651<pre>&lt;?xml version="1.0"?&gt;
2652&lt;!DOCTYPE catalog PUBLIC
2653 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2654 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2655&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2656 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2657 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2658...</pre>
2659
2660<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2661written in XML, there is a specific namespace for catalog elements
2662"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2663catalog is a <code>public</code> mapping it allows to associate a Public
2664Identifier with an URI.</p>
2665<pre>...
2666 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2667 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2668...</pre>
2669
2670<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2671any URI starting with a given prefix should be looked at another URI
2672constructed by replacing the prefix with an new one. In effect this acts like
2673a cache system for a full area of the Web. In practice it is extremely useful
2674with a file prefix if you have installed a copy of those resources on your
2675local system.</p>
2676<pre>...
2677&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2678 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2679&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2680 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2681&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2682 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2683&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2684 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2685&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2686 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2687...</pre>
2688
2689<p>Delegation is the core features which allows to build a tree of catalogs,
2690easier to maintain than a single catalog, based on Public Identifier, System
2691Identifier or URI prefixes it instructs the catalog software to look up
2692entries in another resource. This feature allow to build hierarchies of
2693catalogs, the set of entries presented should be sufficient to redirect the
2694resolution of all DocBook references to the specific catalog in
2695<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2696references for DocBook 4.2.1 to a specific catalog installed at the same time
2697as the DocBook resources on the local machine.</p>
2698
2699<h3><a name="reference">How to tune catalog usage:</a></h3>
2700
2701<p>The user can change the default catalog behaviour by redirecting queries
2702to its own set of catalogs, this can be done by setting the
2703<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2704empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2705default catalog</p>
2706
2707<h3><a name="validate">How to debug catalog processing:</a></h3>
2708
2709<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2710make libxml output debugging informations for each catalog operations, for
2711example:</p>
2712<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2713warning: failed to load external entity "title.xml"
2714orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2715orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2716Failed to parse catalog /etc/xml/catalog
2717Failed to parse catalog /etc/xml/catalog
2718warning: failed to load external entity "title.xml"
2719Catalogs cleanup
2720orchis:~/XML -&gt; </pre>
2721
2722<p>The test/ent2 references an entity, running the parser from memory makes
2723the base URI unavailable and the the "title.xml" entity cannot be loaded.
2724Setting up the debug environment variable allows to detect that an attempt is
2725made to load the <code>/etc/xml/catalog</code> but since it's not present the
2726resolution fails.</p>
2727
2728<p>But the most advanced way to debug XML catalog processing is to use the
2729<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2730catalogs and make resolution queries to see what is going on. This is also
2731used for the regression tests:</p>
2732<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2733 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2734http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2735orchis:~/XML -&gt; </pre>
2736
2737<p>For debugging what is going on, adding one -v flags increase the verbosity
2738level to indicate the processing done (adding a second flag also indicate
2739what elements are recognized at parsing):</p>
2740<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2741 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2742Parsing catalog test/catalogs/docbook.xml's content
2743Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2744http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2745Catalogs cleanup
2746orchis:~/XML -&gt; </pre>
2747
2748<p>A shell interface is also available to debug and process multiple queries
2749(and for regression tests):</p>
2750<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2751 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2752&gt; help
2753Commands available:
2754public PublicID: make a PUBLIC identifier lookup
2755system SystemID: make a SYSTEM identifier lookup
2756resolve PublicID SystemID: do a full resolver lookup
2757add 'type' 'orig' 'replace' : add an entry
2758del 'values' : remove values
2759dump: print the current catalog state
2760debug: increase the verbosity level
2761quiet: decrease the verbosity level
2762exit: quit the shell
2763&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2764http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2765&gt; quit
2766orchis:~/XML -&gt; </pre>
2767
2768<p>This should be sufficient for most debugging purpose, this was actually
2769used heavily to debug the XML Catalog implementation itself.</p>
2770
2771<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2772
2773<p>Basically XML Catalogs are XML files, you can either use XML tools to
2774manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2775to create a catalog the -create option provide this facility:</p>
2776<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2777&lt;?xml version="1.0"?&gt;
2778&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2779 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2780&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2781orchis:~/XML -&gt; </pre>
2782
2783<p>By default xmlcatalog does not overwrite the original catalog and save the
2784result on the standard output, this can be overridden using the -noout
2785option. The <code>-add</code> command allows to add entries in the
2786catalog:</p>
2787<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2788 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2789 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2790orchis:~/XML -&gt; cat tst.xml
2791&lt;?xml version="1.0"?&gt;
2792&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2793 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2794&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2795&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2796 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2797&lt;/catalog&gt;
2798orchis:~/XML -&gt; </pre>
2799
2800<p>The <code>-add</code> option will always take 3 parameters even if some of
2801the XML Catalog constructs (like nextCatalog) will have only a single
2802argument, just pass a third empty string, it will be ignored.</p>
2803
2804<p>Similarly the <code>-del</code> option remove matching entries from the
2805catalog:</p>
2806<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2807 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2808&lt;?xml version="1.0"?&gt;
2809&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2810 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2811&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2812orchis:~/XML -&gt; </pre>
2813
2814<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2815exact and would have worked in a similar fashion with the Public ID
2816string.</p>
2817
2818<p>This is rudimentary but should be sufficient to manage a not too complex
2819catalog tree of resources.</p>
2820
2821<h3><a name="implemento">The implementor corner quick review of the
2822API:</a></h3>
2823
2824<p>First, and like for every other module of libxml, there is an
2825automatically generated <a href="html/libxml-catalog.html">API page for
2826catalog support</a>.</p>
2827
2828<p>The header for the catalog interfaces should be included as:</p>
2829<pre>#include &lt;libxml/catalog.h&gt;</pre>
2830
2831<p>The API is voluntarily kept very simple. First it is not obvious that
2832applications really need access to it since it is the default behaviour of
2833libxml (Note: it is possible to completely override libxml default catalog by
2834using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2835plug an application specific resolver).</p>
2836
2837<p>Basically libxml support 2 catalog lists:</p>
2838<ul>
2839 <li>the default one, global shared by all the application</li>
2840 <li>a per-document catalog, this one is built if the document uses the
2841 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2842 associated to the parser context and destroyed when the parsing context
2843 is destroyed.</li>
2844</ul>
2845
2846<p>the document one will be used first if it exists.</p>
2847
2848<h4>Initialization routines:</h4>
2849
2850<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2851used at startup to initialize the catalog, if the catalog should be
2852initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2853should be called before xmlInitializeCatalog() which would otherwise do a
2854default initialization first.</p>
2855
2856<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2857own catalog list if needed.</p>
2858
2859<h4>Preferences setup:</h4>
2860
2861<p>The XML Catalog spec requires the possibility to select default
2862preferences between public and system delegation,
2863xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2864xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2865be forbidden, allowed for global catalog, for document catalog or both, the
2866default is to allow both.</p>
2867
2868<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2869(through the xmlGenericError() mechanism).</p>
2870
2871<h4>Querying routines:</h4>
2872
2873<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2874and xmlCatalogResolveURI() are relatively explicit if you read the XML
2875Catalog specification they correspond to section 7 algorithms, they should
2876also work if you have loaded an SGML catalog with a simplified semantic.</p>
2877
2878<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2879operate on the document catalog list</p>
2880
2881<h4>Cleanup and Miscellaneous:</h4>
2882
2883<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2884the per-document equivalent.</p>
2885
2886<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2887first catalog in the global list, and xmlCatalogDump() allows to dump a
2888catalog state, those routines are primarily designed for xmlcatalog, I'm not
2889sure that exposing more complex interfaces (like navigation ones) would be
2890really useful.</p>
2891
2892<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2893it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2894provided because this functionality may be useful for client tools.</p>
2895
2896<h4>threaded environments:</h4>
2897
2898<p>Since the catalog tree is built progressively, some care has been taken to
2899try to avoid troubles in multithreaded environments. The code is now thread
2900safe assuming that the libxml library has been compiled with threads
2901support.</p>
2902
2903<p></p>
2904
2905<h3><a name="Other">Other resources</a></h3>
2906
2907<p>The XML Catalog specification is relatively recent so there isn't much
2908literature to point at:</p>
2909<ul>
2910 <li>You can find an good rant from Norm Walsh about <a
2911 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2912 need for catalogs</a>, it provides a lot of context informations even if
2913 I don't agree with everything presented.</li>
2914 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2915 catalog proposal</a> from John Cowan</li>
2916 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2917 Language</a> (RDDL) another catalog system but more oriented toward
2918 providing metadata for XML namespaces.</li>
2919 <li>the page from the OASIS Technical <a
2920 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2921 Resolution</a> who maintains XML Catalog, you will find pointers to the
2922 specification update, some background and pointers to others tools
2923 providing XML Catalog support</li>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2924 <li>Here is a <a href="buildDocBookCatalog">shell script</a> to generate
2925 XML Catalogs for DocBook 4.1.2 . If it can write to the /etc/xml/
2926 directory, it will set-up /etc/xml/catalog and /etc/xml/docbook based on
2927 the resources found on the system. Otherwise it will just create
2928 ~/xmlcatalog and ~/dbkxmlcatalog and doing:
Daniel Veillardc575b992002-02-08 13:28:40 +0000[diff] [blame]2929 <p><code>export XMLCATALOG=$HOME/xmlcatalog</code></p>
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2930 <p>should allow to process DocBook documentations without requiring
2931 network accesses for the DTd or stylesheets</p>
2932 </li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2933 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
Daniel Veillard35e937a2002-01-19 22:21:54 +0000[diff] [blame]2934 small tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems
2935 to work fine for me too</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2936 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2937 manual page</a></li>
2938</ul>
2939
2940<p>If you have suggestions for corrections or additions, simply contact
2941me:</p>
2942
2943<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2944
2945<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2946using the XML library from the C language. It is not intended to be
2947extensive. I hope the automatically generated documents will provide the
2948completeness required, but as a separate set of documents. The interfaces of
2949the XML library are by principle low level, there is nearly zero abstraction.
2950Those interested in a higher level API should <a href="#DOM">look at
2951DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2952
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2953<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2954separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2955interfaces</a>. Let's have a look at how the XML parser can be called:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2956
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2957<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2958
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2959<p>Usually, the first thing to do is to read an XML input. The parser accepts
2960documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2961defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2962<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2963 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2964 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2965 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2966</dl>
2967<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2968 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2969 <dd><p>Parse an XML document contained in a (possibly compressed)
2970 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2971 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2972</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2973
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2974<p>The parser returns a pointer to the document structure (or NULL in case of
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2975failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2976
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2977<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2978
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2979<p>In order for the application to keep the control when the document is
2980being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2981interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2982<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2983 void *user_data,
2984 const char *chunk,
2985 int size,
2986 const char *filename);
2987int xmlParseChunk (xmlParserCtxtPtr ctxt,
2988 const char *chunk,
2989 int size,
2990 int terminate);</pre>
2991
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2992<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2993<pre> FILE *f;
2994
2995 f = fopen(filename, "r");
2996 if (f != NULL) {
2997 int res, size = 1024;
2998 char chars[1024];
2999 xmlParserCtxtPtr ctxt;
3000
3001 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3002 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3003 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
3004 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3005 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3006 xmlParseChunk(ctxt, chars, res, 0);
3007 }
3008 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3009 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3010 xmlFreeParserCtxt(ctxt);
3011 }
3012 }</pre>
3013
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3014<p>The HTML parser embedded into libxml also has a push interface; the
3015functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3016
3017<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
3018
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3019<p>The tree-building interface makes the parser memory-hungry, first loading
3020the document in memory and then building the tree itself. Reading a document
3021without building the tree is possible using the SAX interfaces (see SAX.h and
3022<a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3023Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3024limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3025<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3026
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3027<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3028
3029<p>The other way to get an XML tree in memory is by building it. Basically
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3030there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3031also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
3032code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3033<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3034 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3035 xmlNodePtr tree, subtree;
3036
3037 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3038 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
3039 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
3040 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
3041 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3042 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3043 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3044 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
3045 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
3046 subtree = xmlNewChild(tree, NULL, "image", NULL);
3047 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3048
3049<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3050
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3051<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3052
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3053<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3054code has access to the internal structure of all the elements of the tree.
3055The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]3056<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3057<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]3058example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3059<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3060
3061<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3062<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3063
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3064<p>points to the text node containing the chapter title "The Linux
3065adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3066
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3067<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3068present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3069to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]3070<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]3071
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3072<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3073
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3074<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3075is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3076<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3077 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
3078 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3079 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
3080 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3081 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3082</dl>
3083<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3084 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3085 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]3086 <dd><p>This function returns a pointer to new copy of the property
3087 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3088 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3089</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3090
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3091<p>Two functions are provided for reading and writing the text associated
3092with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3093<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3094 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3095 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3096 <dd><p>This function takes an "external" string and converts it to one
3097 text node or possibly to a list of entity and text nodes. All
3098 non-predefined entity references like &amp;Gnome; will be stored
3099 internally as entity nodes, hence the result of the function may not be
3100 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3101 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3102</dl>
3103<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3104 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3105 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3106 <dd><p>This function is the inverse of
3107 <code>xmlStringGetNodeList()</code>. It generates a new string
3108 containing the content of the text and entity nodes. Note the extra
3109 argument inLine. If this argument is set to 1, the function will expand
3110 entity references. For example, instead of returning the &amp;Gnome;
3111 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3112 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3113 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3114</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3115
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3116<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3117
3118<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3119<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]3120 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3121 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3122 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3123 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3124</dl>
3125<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3126 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3127 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3128 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3129</dl>
3130<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3131 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3132 <dd><p>Saves the document to a file. In this case, the compression
3133 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3134 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3135</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]3136
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3137<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3138
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3139<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3140accesses. The level of compression on saves can be turned on either globally
3141or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3142<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3143 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3144 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3145 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3146</dl>
3147<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3148 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3149 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3150 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3151</dl>
3152<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3153 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3154 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3155 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3156</dl>
3157<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3158 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3159 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3160 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]3161</dl>
3162
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3163<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3164
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3165<p>Entities in principle are similar to simple C macros. An entity defines an
3166abbreviation for a given string that you can reuse many times throughout the
3167content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3168may occur frequently within a document, or to confine the change needed to a
3169document to a restricted area in the internal subset of the document (at the
3170beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3171<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31722 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31733 &lt;!ENTITY xml "Extensible Markup Language"&gt;
31744 ]&gt;
31755 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]31766 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]31777 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3178
3179<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3180its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3181are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3182predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3183<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3184for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3185<strong>&amp;quot;</strong> for the character '"', and
3186<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3187
3188<p>One of the problems related to entities is that you may want the parser to
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3189substitute an entity's content so that you can see the replacement text in
3190your application. Or you may prefer to keep entity references as such in the
3191content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3192precious information (if the user went through the pain of explicitly
3193defining entities, he may have a a rather negative attitude if you blindly
3194susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]3195href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3196function allows you to check and change the behaviour, which is to not
3197substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3198
3199<p>Here is the DOM tree built by libxml for the previous document in the
3200default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3201<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3202DOCUMENT
3203version=1.0
3204 ELEMENT EXAMPLE
3205 TEXT
3206 content=
3207 ENTITY_REF
3208 INTERNAL_GENERAL_ENTITY xml
3209 content=Extensible Markup Language
3210 TEXT
3211 content=</pre>
3212
3213<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3214<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3215DOCUMENT
3216version=1.0
3217 ELEMENT EXAMPLE
3218 TEXT
3219 content= Extensible Markup Language</pre>
3220
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3221<p>So, entities or no entities? Basically, it depends on your use case. I
3222suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3223entities in your XML document or data if you are not willing to handle the
3224entity references elements in the DOM tree.</p>
3225
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3226<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3227entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3228transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3229reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3230finding them in the input).</p>
3231
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3232<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3233on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3234non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3235then using the SAX API may be long. If you plan to use complex documents, I
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3236strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]3237deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]3238
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]3239<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3240
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3241<p>The libxml library implements <a
3242href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
3243recognizing namespace contructs in the input, and does namespace lookup
3244automatically when building the DOM tree. A namespace declaration is
3245associated with an in-memory structure and all elements or attributes within
3246that namespace point to it. Hence testing the namespace is a simple and fast
3247equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3248
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3249<p>I suggest that people using libxml use a namespace, and declare it in the
3250root element of their document as the default namespace. Then they don't need
3251to use the prefix in the content but we will have a basis for future semantic
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3252refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3253the size of the XML output significantly, but significantly increases its
3254value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3255<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
3256 &lt;elem1&gt;...&lt;/elem1&gt;
3257 &lt;elem2&gt;...&lt;/elem2&gt;
3258&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3259
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3260<p>The namespace value has to be an absolute URL, but the URL doesn't have to
3261point to any existing resource on the Web. It will bind all the element and
3262atributes with that URL. I suggest to use an URL within a domain you control,
3263and that the URL should contain some kind of version information if possible.
3264For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
3265namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3266
3267<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]3268version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3269and if the version information don't match something you know, warn the user
3270and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3271namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3272same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3273associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3274just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]3275<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3276prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3277
3278<p>@@Interfaces@@</p>
3279
3280<p>@@Examples@@</p>
3281
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3282<p>Usually people object to using namespaces together with validity checking.
3283I will try to make sure that using namespaces won't break validity checking,
3284so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]3285suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3286<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3287flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3288from multiple DTDs will certainly break current validation schemes. I will
3289try to provide ways to do this, but this may not be portable or
3290standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3291
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3292<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3293
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3294<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3295
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3296<p>Version 2 of libxml is the first version introducing serious backward
3297incompatible changes. The main goals were:</p>
3298<ul>
3299 <li>a general cleanup. A number of mistakes inherited from the very early
3300 versions couldn't be changed due to compatibility constraints. Example
3301 the "childs" element in the nodes.</li>
3302 <li>Uniformization of the various nodes, at least for their header and link
3303 parts (doc, parent, children, prev, next), the goal is a simpler
3304 programming model and simplifying the task of the DOM implementors.</li>
3305 <li>better conformances to the XML specification, for example version 1.x
3306 had an heuristic to try to detect ignorable white spaces. As a result the
3307 SAX event generated were ignorableWhitespace() while the spec requires
3308 character() in that case. This also mean that a number of DOM node
3309 containing blank text may populate the DOM tree which were not present
3310 before.</li>
3311</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3312
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3313<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3314
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3315<p>So client code of libxml designed to run with version 1.x may have to be
3316changed to compile against version 2.x of libxml. Here is a list of changes
3317that I have collected, they may not be sufficient, so in case you find other
3318change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
3319mail</a>:</p>
3320<ol>
3321 <li>The package name have changed from libxml to libxml2, the library name
3322 is now -lxml2 . There is a new xml2-config script which should be used to
3323 select the right parameters libxml2</li>
3324 <li>Node <strong>childs</strong> field has been renamed
3325 <strong>children</strong> so s/childs/children/g should be applied
3326 (probablility of having "childs" anywere else is close to 0+</li>
3327 <li>The document don't have anymore a <strong>root</strong> element it has
3328 been replaced by <strong>children</strong> and usually you will get a
3329 list of element here. For example a Dtd element for the internal subset
3330 and it's declaration may be found in that list, as well as processing
3331 instructions or comments found before or after the document root element.
3332 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
3333 a document. Alternatively if you are sure to not reference Dtds nor have
3334 PIs or comments before or after the root element
3335 s/-&gt;root/-&gt;children/g will probably do it.</li>
3336 <li>The white space issue, this one is more complex, unless special case of
3337 validating parsing, the line breaks and spaces usually used for indenting
3338 and formatting the document content becomes significant. So they are
3339 reported by SAX and if your using the DOM tree, corresponding nodes are
3340 generated. Too approach can be taken:
3341 <ol>
3342 <li>lazy one, use the compatibility call
3343 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
3344 relying on a special (and possibly broken) set of heuristics of
3345 libxml to detect ignorable blanks. Don't complain if it breaks or
3346 make your application not 100% clean w.r.t. to it's input.</li>
3347 <li>the Right Way: change you code to accept possibly unsignificant
3348 blanks characters, or have your tree populated with weird blank text
3349 nodes. You can spot them using the comodity function
3350 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
3351 nodes.</li>
3352 </ol>
3353 <p>Note also that with the new default the output functions don't add any
3354 extra indentation when saving a tree in order to be able to round trip
3355 (read and save) without inflating the document with extra formatting
3356 chars.</p>
3357 </li>
3358 <li>The include path has changed to $prefix/libxml/ and the includes
3359 themselves uses this new prefix in includes instructions... If you are
3360 using (as expected) the
3361 <pre>xml2-config --cflags</pre>
3362 <p>output to generate you compile commands this will probably work out of
3363 the box</p>
3364 </li>
3365 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
3366 byte of the head of the document available for character detection.</li>
3367</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3368
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3369<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3370
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3371<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
3372to allow smoth upgrade of existing libxml v1code while retaining
3373compatibility. They offers the following:</p>
3374<ol>
3375 <li>similar include naming, one should use
3376 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
3377 <li>similar identifiers defined via macros for the child and root fields:
3378 respectively <strong>xmlChildrenNode</strong> and
3379 <strong>xmlRootNode</strong></li>
3380 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
3381 inserted once in the client code</li>
3382</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3383
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3384<p>So the roadmap to upgrade your existing libxml applications is the
3385following:</p>
3386<ol>
3387 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
3388 <li>find all occurences where the xmlDoc <strong>root</strong> field is
3389 used and change it to <strong>xmlRootNode</strong></li>
3390 <li>similary find all occurences where the xmlNode <strong>childs</strong>
3391 field is used and change it to <strong>xmlChildrenNode</strong></li>
3392 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
3393 <strong>main()</strong> or in the library init entry point</li>
3394 <li>Recompile, check compatibility, it should still work</li>
3395 <li>Change your configure script to look first for xml2-config and fallback
3396 using xml-config . Use the --cflags and --libs ouptut of the command as
3397 the Include and Linking parameters needed to use libxml.</li>
3398 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
3399 libxml-devel-1.8.y can be kept simultaneously)</li>
3400 <li>remove your config.cache, relaunch your configuration mechanism, and
3401 recompile, if steps 2 and 3 were done right it should compile as-is</li>
3402 <li>Test that your application is still running correctly, if not this may
3403 be due to extra empty nodes due to formating spaces being kept in libxml2
3404 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
3405 code before calling the parser (next to
3406 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
3407</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3408
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3409<p>Following those steps should work. It worked for some of my own code.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3410
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3411<p>Let me put some emphasis on the fact that there is far more changes from
3412libxml 1.x to 2.x than the ones you may have to patch for. The overall code
3413has been considerably cleaned up and the conformance to the XML specification
3414has been drastically improved too. Don't take those changes as an excuse to
3415not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3416
Daniel Veillard52dcab32001-10-30 12:51:17 +0000[diff] [blame]3417<h2><a name="Thread">Thread safety</a></h2>
3418
3419<p>Starting with 2.4.7, libxml makes provisions to ensure that concurent
3420threads can safely work in parallel parsing different documents. There is
3421however a couple of things to do to ensure it:</p>
3422<ul>
3423 <li>configure the library accordingly using the --with-threads options</li>
3424 <li>call xmlInitParser() in the "main" thread before using any of the
3425 libxml API (except possibly selecting a different memory allocator)</li>
3426</ul>
3427
3428<p>Note that the thread safety cannot be ensured for multiple threads sharing
3429the same document, the locking must be done at the application level, libxml
3430exports a basic mutex and reentrant mutexes API in &lt;libxml/threads.h&gt;.
3431The parts of the library checked for thread safety are:</p>
3432<ul>
3433 <li>concurrent loading</li>
3434 <li>file access resolution</li>
3435 <li>catalog access</li>
3436 <li>catalog building</li>
3437 <li>entities lookup/accesses</li>
3438 <li>validation</li>
3439 <li>global variables per-thread override</li>
3440 <li>memory handling</li>
3441</ul>
3442
3443<p>XPath is supposed to be thread safe now, but this wasn't tested
3444seriously.</p>
3445
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3446<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3447
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3448<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3449Object Model</em>; this is an API for accessing XML or HTML structured
3450documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3451and will be based on gnome-xml. This will be a far cleaner interface to
3452manipulate XML files within Gnome since it won't expose the internal
3453structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3454
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3455<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3456href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3457is a full DOM interface, thanks to Paolo Casarini, check the <a
3458href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3459informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3460
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3461<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3462
3463<p>Here is a real size example, where the actual content of the application
3464data is not kept in the DOM tree but uses internal structures. It is based on
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3465a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3466storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3467base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3468<pre>&lt;?xml version="1.0"?&gt;
3469&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3470 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3471
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3472 &lt;gjob:Job&gt;
3473 &lt;gjob:Project ID="3"/&gt;
3474 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3475 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3476
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3477 &lt;gjob:Update&gt;
3478 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3479 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3480 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3481 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3482
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3483 &lt;gjob:Developers&gt;
3484 &lt;gjob:Developer&gt;
3485 &lt;/gjob:Developer&gt;
3486 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3487
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3488 &lt;gjob:Contact&gt;
3489 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3490 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3491 &lt;gjob:Company&gt;
3492 &lt;/gjob:Company&gt;
3493 &lt;gjob:Organisation&gt;
3494 &lt;/gjob:Organisation&gt;
3495 &lt;gjob:Webpage&gt;
3496 &lt;/gjob:Webpage&gt;
3497 &lt;gjob:Snailmail&gt;
3498 &lt;/gjob:Snailmail&gt;
3499 &lt;gjob:Phone&gt;
3500 &lt;/gjob:Phone&gt;
3501 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3502
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3503 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3504 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3505 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3506
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3507 &lt;gjob:Skills&gt;
3508 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3509
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3510 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3511 A GNOME based system that will allow a superuser to configure
3512 compressed and uncompressed files and/or file systems to be backed
3513 up with a supported media in the system. This should be able to
3514 perform via find commands generating a list of files that are passed
3515 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3516 or via operations performed on the filesystem itself. Email
3517 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3518 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3519
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3520 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3521
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3522 &lt;/gjob:Jobs&gt;
3523&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3524
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3525<p>While loading the XML file into an internal DOM tree is a matter of
3526calling only a couple of functions, browsing the tree to gather the ata and
3527generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3528
3529<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3530structure. For example, the ordering of the attributes is not significant,
3531the XML specification is clear about it. It's also usually a good idea not to
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3532depend on the order of the children of a given node, unless it really makes
3533things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3534<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3535 * A person record
3536 */
3537typedef struct person {
3538 char *name;
3539 char *email;
3540 char *company;
3541 char *organisation;
3542 char *smail;
3543 char *webPage;
3544 char *phone;
3545} person, *personPtr;
3546
3547/*
3548 * And the code needed to parse it
3549 */
3550personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3551 personPtr ret = NULL;
3552
3553DEBUG("parsePerson\n");
3554 /*
3555 * allocate the struct
3556 */
3557 ret = (personPtr) malloc(sizeof(person));
3558 if (ret == NULL) {
3559 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3560 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3561 }
3562 memset(ret, 0, sizeof(person));
3563
3564 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3565 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3566 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3567 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3568 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3569 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3570 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3571 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3572 }
3573
3574 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3575}</pre>
3576
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3577<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3578<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3579 <li>Usually a recursive parsing style is the more convenient one: XML data
3580 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3581 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3582 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3583 i.e. the pointer to the global XML document and the namespace reserved to
3584 the application. Document wide information are needed for example to
3585 decode entities and it's a good coding practice to define a namespace for
3586 your application set of data and test that the element and attributes
3587 you're analyzing actually pertains to your application space. This is
3588 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3589 <li>To retrieve text and attributes value, you can use the function
3590 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3591 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3592</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3593
3594<p>Here is another piece of code used to parse another level of the
3595structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3596<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3597/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3598 * a Description for a Job
3599 */
3600typedef struct job {
3601 char *projectID;
3602 char *application;
3603 char *category;
3604 personPtr contact;
3605 int nbDevelopers;
3606 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3607} job, *jobPtr;
3608
3609/*
3610 * And the code needed to parse it
3611 */
3612jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3613 jobPtr ret = NULL;
3614
3615DEBUG("parseJob\n");
3616 /*
3617 * allocate the struct
3618 */
3619 ret = (jobPtr) malloc(sizeof(job));
3620 if (ret == NULL) {
3621 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3622 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3623 }
3624 memset(ret, 0, sizeof(job));
3625
3626 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3627 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3628 while (cur != NULL) {
3629
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3630 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3631 ret-&gt;projectID = xmlGetProp(cur, "ID");
3632 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3633 fprintf(stderr, "Project has no ID\n");
3634 }
3635 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3636 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3637 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3638 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3639 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3640 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3641 ret-&gt;contact = parsePerson(doc, ns, cur);
3642 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3643 }
3644
3645 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3646}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3647
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3648<p>Once you are used to it, writing this kind of code is quite simple, but
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3649boring. Ultimately, it could be possble to write stubbers taking either C
3650data structure definitions, a set of XML examples or an XML DTD and produce
3651the code needed to import and export the content between C data and XML
3652storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3653
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3654<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3655parsing example</a> as a template, it is also available with Makefile in the
3656Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3657
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3658<h2><a name="Contributi">Contributions</a></h2>
3659<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3660 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3661 patches, Gary Pennington worked on the validation API, threading support
3662 and Solaris port.</li>
3663 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3664 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3665 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3666 Website: <a
3667 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3668 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame]3669 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3670 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3671 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3672 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3673 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3674 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
Daniel Veillarddb9dfd92001-11-26 17:25:02 +0000[diff] [blame]3675 provides <a href="http://garypennington.net/libxml2/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3676 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3677 <li><a
3678 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3679 Sergeant</a>
3680 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3681 wrapper for libxml2/libxslt as part of the <a
3682 href="http://axkit.com/">AxKit XML application server</a></li>
3683 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3684 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3685 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3686 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3687 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3688 provided <a href="http://xmlsoft.org/messages/0488.html">man
3689 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3690 <li>there is a module for <a
3691 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3692 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3693 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3694 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3695 for Python</a></li>
Daniel Veillard1aadc442001-11-28 13:10:32 +0000[diff] [blame]3696 <li>Petr Kozelka provides <a
3697 href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
3698 libxml2</a> with Kylix and Delphi and other Pascal compilers</li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3699</ul>
3700
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3701<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3702</body>
3703</html>