Gitiles
Code Review Sign In
gerrit-public.fairphone.software / platform / external / libxml2 / c6271d208e0dc8768aac1dd7c162ddef121fbaa3 / . / doc / xml.html
blob: 4cc6872b07f5407c7bbcd2362b3eca20854c45d0 [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
56strict way. To some extent libxml2 provide some support for the following
57other specification but don't claim to implement them:</p>
58<ul>
59 <li>Document Object Model (DOM) <a
60 href="http://www.w3.org/TR/DOM-Level-2-Core/">http://www.w3.org/TR/DOM-Level-2-Core/</a>
61 it doesn't implement the API itself, gdome2 does this in top of
62 libxml2</li>
63 <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^]64 : libxml implements a basic FTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]65 <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^]66 : HTTP/1.0, again a basic HTTP client code</li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]67 <li>SAX: a minimal SAX implementation compatible with early expat
68 versions</li>
69 <li>DocBook SGML v4: libxml2 includes a hackish parser to transition to
70 XML</li>
71</ul>
72
73<p></p>
74
Daniel Veillard96984452000-08-31 13:50:12 +0000[diff] [blame]75<p>Separate documents:</p>
76<ul>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame^]77 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a>
78 providing an implementation of XSLT 1.0 and extensions on top of
79 libxml2</li>
80 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>
81 : a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]82</ul>
83
84<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]85
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]86<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]87href="http://www.w3.org/XML/">XML</a> C library developped for the <a
88href="http://www.gnome.org/">Gnome</a> project. <a
89href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
90structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]91
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]92<p>Here are some key points about libxml:</p>
93<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]94 <li>Libxml exports Push and Pull type parser interfaces for both XML and
95 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]96 <li>Libxml can do DTD validation at parse time, using a parsed document
97 instance, or with an arbitrary DTD.</li>
98 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]99 href="http://www.w3.org/TR/xpath">XPath</a>, <a
100 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
101 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]102 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]103 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]104 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]105 <li>Basic support for HTTP and FTP client allowing aplications to fetch
106 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]107 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]108 <li>The internal document repesentation is as close as possible to the <a
109 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
110 <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]111 like interface</a>; the interface is designed to be compatible with <a
112 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]113 <li>This library is released both under the <a
114 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]115 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
116 LGPL</a>. Use either at your convenience, basically this should make
117 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]118</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]119
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]120<p>Warning: unless you are forced to because your application links with a
121Gnome library requiring it, <strong><span
122style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
123libxml2</p>
124
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]125<h2><a name="FAQ">FAQ</a></h2>
126
127<p>Table of Content:</p>
128<ul>
129 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
130 <li><a href="FAQ.html#Installati">Installation</a></li>
131 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
132 <li><a href="FAQ.html#Developer">Developer corner</a></li>
133</ul>
134
135<h3><a name="Licence">Licence</a>(s)</h3>
136<ol>
137 <li><em>Licensing Terms for libxml</em>
138 <p>libxml is released under 2 (compatible) licences:</p>
139 <ul>
140 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
141 Library General Public License</li>
142 <li>the <a
143 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
144 IPR</a>: very similar to the XWindow licence</li>
145 </ul>
146 </li>
147 <li><em>Can I embed libxml in a proprietary application ?</em>
148 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
149 made to libxml, but it would be graceful to provide back bugfixes and
150 improvements as patches for possible incorporation in the main
151 development tree</p>
152 </li>
153</ol>
154
155<h3><a name="Installati">Installation</a></h3>
156<ol>
157 <li>Unless you are forced to because your application links with a Gnome
158 library requiring it, <strong><span style="background-color: #FF0000">Do
159 Not Use libxml1</span></strong>, use libxml2</li>
160 <li><em>Where can I get libxml</em>
161 ?
162 <p>The original distribution comes from <a
163 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
164 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
165 <p>Most linux and Bsd distribution includes libxml, this is probably the
166 safer way for end-users</p>
167 <p>David Doolin provides precompiled Windows versions at <a
168 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
169 </li>
170 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
171 <ul>
172 <li>If you are not concerned by any existing backward compatibility
173 with existing application, install libxml2 only</li>
174 <li>If you are not doing development, you can safely install both.
175 usually the packages <a
176 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
177 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
178 compatible (this is not the case for development packages)</li>
179 <li>If you are a developer and your system provides separate packaging
180 for shared libraries and the development components, it is possible
181 to install libxml and libxml2, and also <a
182 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
183 and <a
184 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
185 too for libxml2 &gt;= 2.3.0</li>
186 <li>If you are developing a new application, please develop against
187 libxml2(-devel)</li>
188 </ul>
189 </li>
190 <li><em>I can't install the libxml package it conflicts with libxml0</em>
191 <p>You probably have an old libxml0 package used to provide the shared
192 library for libxml.so.0, you can probably safely remove it. Anyway the
193 libxml packages provided on <a
194 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
195 libxml.so.0</p>
196 </li>
197 <li><em>I can't install the libxml(2) RPM package due to failed
198 dependancies</em>
199 <p>The most generic solution is to refetch the latest src.rpm , and
200 rebuild it locally with</p>
201 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
202 <p>if everything goes well it will generate two binary rpm (one providing
203 the shared libs and xmllint, and the other one, the -devel package
204 providing includes, static libraries and scripts needed to build
205 applications with libxml(2)) that you can install locally.</p>
206 </li>
207</ol>
208
209<h3><a name="Compilatio">Compilation</a></h3>
210<ol>
211 <li><em>What is the process to compile libxml ?</em>
212 <p>As most UNIX libraries libxml follows the "standard":</p>
213 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
214 <p><code>cd libxml-xxxx</code></p>
215 <p><code>./configure --help</code></p>
216 <p>to see the options, then the compilation/installation proper</p>
217 <p><code>./configure [possible options]</code></p>
218 <p><code>make</code></p>
219 <p><code>make install</code></p>
220 <p>At that point you may have to rerun ldconfig or similar utility to
221 update your list of installed shared libs.</p>
222 </li>
223 <li><em>What other libraries are needed to compile/install libxml ?</em>
224 <p>Libxml does not requires any other library, the normal C ANSI API
225 should be sufficient (please report any violation to this rule you may
226 find).</p>
227 <p>However if found at configuration time libxml will detect and use the
228 following libs:</p>
229 <ul>
230 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
231 : a highly portable and available widely compression library</li>
232 <li>iconv: a powerful character encoding conversion library. It's
233 included by default on recent glibc libraries, so it doesn't need to
234 be installed specifically on linux. It seems it's now <a
235 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
236 of the official UNIX</a> specification. Here is one <a
237 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
238 of the library</a> which source can be found <a
239 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
240 </ul>
241 </li>
242 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
243 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
244 CFLAGS</p>
245 <p>you can also install and use gcc instead or use a precompiled version
246 of libxml, both available from the <a
247 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
248 and Archive Centre</a></p>
249 </li>
250 <li><em>make check fails on some platforms</em>
251 <p>Sometime the regression tests results don't completely match the value
252 produced by the parser, and the makefile uses diff to print the delta. On
253 some platforms the diff return breaks the compilation process, if the
254 diff is small this is probably not a serious problem</p>
255 </li>
256 <li><em>I use the CVS version and there is no configure script</em>
257 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
258 script to regenerate the configure and Makefiles, like:</p>
259 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
260 </li>
261 <li><em>I have troubles when running make tests with gcc-3.0</em>
262 <p>It seems the initial release of gcc-3.0 has a problem with the
263 optimizer which miscompiles the URI module. Please use another
264 compiler</p>
265 </li>
266</ol>
267
268<h3><a name="Developer">Developer</a> corner</h3>
269<ol>
270 <li><em>xmlDocDump() generates output on one line</em>
271 <p>libxml will not <strong>invent</strong> spaces in the content of a
272 document since <strong>all spaces in the content of a document are
273 significant</strong>. If you build a tree from the API and want
274 indentation:</p>
275 <ol>
276 <li>the correct way is to generate those yourself too</li>
277 <li>the dangerous way is to ask libxml to add those blanks to your
278 content <strong>modifying the content of your document in the
279 process</strong>. The result may not be what you expect. There is
280 <strong>NO</strong> way to guarantee that such a modification won't
281 impact other part of the content of your document. See <a
282 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
283 ()</a> and <a
284 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
285 ()</a></li>
286 </ol>
287 </li>
288 <li>Extra nodes in the document:
289 <p><em>For a XML file as below:</em></p>
290 <pre>&lt;?xml version="1.0"?&gt;
291&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
292&lt;NODE CommFlag="0"/&gt;
293&lt;NODE CommFlag="1"/&gt;
294&lt;/PLAN&gt;</pre>
295 <p><em>after parsing it with the function
296 pxmlDoc=xmlParseFile(...);</em></p>
297 <p><em>I want to the get the content of the first node (node with the
298 CommFlag="0")</em></p>
299 <p><em>so I did it as following;</em></p>
300 <pre>xmlNodePtr pode;
301pnode=pxmlDoc-&gt;children-&gt;children;</pre>
302 <p><em>but it does not work. If I change it to</em></p>
303 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
304 <p><em>then it works. Can someone explain it to me.</em></p>
305 <p></p>
306 <p>In XML all characters in the content of the document are significant
307 <strong>including blanks and formatting line breaks</strong>.</p>
308 <p>The extra nodes you are wondering about are just that, text nodes with
309 the formatting spaces wich are part of the document but that people tend
310 to forget. There is a function <a
311 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
312 ()</a> to remove those at parse time, but that's an heuristic, and its
313 use should be limited to case where you are sure there is no
314 mixed-content in the document.</p>
315 </li>
316 <li><em>I get compilation errors of existing code like when accessing
317 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
318 <p>You are compiling code developed for libxml version 1 and using a
319 libxml2 development environment. Either switch back to libxml v1 devel or
320 even better fix the code to compile with libxml2 (or both) by <a
321 href="upgrade.html">following the instructions</a>.</p>
322 </li>
323 <li><em>I get compilation errors about non existing
324 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
325 fields</em>
326 <p>The source code you are using has been <a
327 href="upgrade.html">upgraded</a> to be able to compile with both libxml
328 and libxml2, but you need to install a more recent version:
329 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
330 </li>
331 <li><em>XPath implementation looks seriously broken</em>
332 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
333 a recent version, the implementation and debug of libxslt generated fixes
334 for most obvious problems.</p>
335 </li>
336 <li><em>The example provided in the web page does not compile</em>
337 <p>It's hard to maintain the documentation in sync with the code
338 &lt;grin/&gt; ...</p>
339 <p>Check the previous points 1/ and 2/ raised before, and send
340 patches.</p>
341 </li>
342 <li><em>Where can I get more examples and informations than in the web
343 page</em>
344 <p>Ideally a libxml book would be nice. I have no such plan ... But you
345 can:</p>
346 <ul>
347 <li>check more deeply the <a href="html/libxml-lib.html">existing
348 generated doc</a></li>
349 <li>looks for examples of use for libxml function using the Gnome code
350 for example the following will query the full Gnome CVs base for the
351 use of the <strong>xmlAddChild()</strong> function:
352 <p><a
353 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
354 <p>This may be slow, a large hardware donation to the gnome project
355 could cure this :-)</p>
356 </li>
357 <li><a
358 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
359 the libxml source</a>
360 , I try to write code as clean and documented as possible, so
361 looking at it may be helpful</li>
362 </ul>
363 </li>
364 <li>What about C++ ?
365 <p>libxml is written in pure C in order to allow easy reuse on a number
366 of platforms, including embedded systems. I don't intend to convert to
367 C++.</p>
368 <p>There is however a C++ wrapper provided by Ari Johnson
369 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
370 <p>Website: <a
371 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
372 <p>Download: <a
373 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
374 </li>
375 <li>How to validate a document a posteriori ?
376 <p>It is possible to validate documents which had not been validated at
377 initial parsing time or documents who have been built from scratch using
378 the API. Use the <a
379 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
380 function. It is also possible to simply add a Dtd to an existing
381 document:</p>
382 <pre>xmlDocPtr doc; /* your existing document */
383 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
384 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
385
386 doc-&gt;intSubset = dtd;
387 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
388 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
389 </pre>
390 </li>
391 <li>etc ...</li>
392</ol>
393
394<p></p>
395
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]396<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]397
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]398<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]399<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]400 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]401 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]402 documentation</a> automatically extracted from code comments (using <a
403 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
404 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]405 <li>Look at the documentation about <a href="encoding.html">libxml
406 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]407 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]408 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]409 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
410 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]411 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
412 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]413 <li>George Lebl wrote <a
414 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]415 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]416 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
417 file</a></li>
418 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
419 starting a new project using libxml you should really use the 2.x
420 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]421 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]422 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]423</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]424
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]425<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]426
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]427<p>Well, bugs or missing features are always possible, and I will make a
428point of fixing them in a timely fashion. The best way to report a bug is to
429use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
430bug tracking database</a> (make sure to use the "libxml" module name). I look
431at reports there regularly and it's good to have a reminder when a bug is
432still open. Check the <a
433href="http://bugzilla.gnome.org/bugwritinghelp.html">instructions on
434reporting bugs</a> and be sure to specify that the bug is for the package
435libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]436
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]437<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]438href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
439href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]440href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
441please visit the <a
442href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
443follow the instructions. <strong>Do not send code, I won't debug it</strong>
444(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]445
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]446<p>Check the following <strong><span style="color: #FF0000">before
447posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]448<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]449 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]450 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
451 version</a>, and that the problem still shows up in those</li>
452 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
453 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]454 there is probably a fix available, similary check the <a
455 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]456 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]457 <li>make sure you can reproduce the bug with xmllint or one of the test
458 programs found in source in the distribution</li>
459 <li>Please send the command showing the error as well as the input (as an
460 attachement)</li>
461</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]462
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]463<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]464href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]465related I will approve it.. Please do not send me mail directly, it makes
466things really harder to track and in some cases I'm not the best person to
467answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]468
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]469<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]470probably be processed faster.</p>
471
472<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]473href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]474provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]475questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]476documentantion</a> is not as polished as I would like (i need to learn more
477about Docbook), but it's a good starting point.</p>
478
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]479<h2><a name="help">How to help</a></h2>
480
481<p>You can help the project in various ways, the best thing to do first is to
482subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]483href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
484href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]485database:</a>:</p>
486<ol>
487 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]488 <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]489 be integrated in all cases but help pinpointing portability problems
490 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]491 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]492 as HTML diffs).</li>
493 <li>provide new documentations pieces (translations, examples, etc ...)</li>
494 <li>Check the TODO file and try to close one of the items</li>
495 <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]496 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
497 </a>before to avoid synchronization problems and check that the suggested
498 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]499</ol>
500
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]501<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]502
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]503<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]504href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
505href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
506href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]507href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]508as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]509archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]510href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
511packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]512href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
513href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]514packages installed to compile applications using libxml.) <a
515href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
516of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]517href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame^]518provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
519Pennington</a> provides <a
520href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]521
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]522<p><a name="Snapshot">Snapshot:</a></p>
523<ul>
524 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]525 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]526 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]527 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]528</ul>
529
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame^]530<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]531
532<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame^]533platform, get in touch with me to upload the package, wrappers for various
534languages have been provided, and can be found in the
535<a href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]536
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]537<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]538<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]539 <li><p>The <a
540 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]541 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]542 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
543 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]544 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]545 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]546</ul>
547
548<h2><a name="News">News</a></h2>
549
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]550<h3>CVS only : check the <a
551href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]552for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]553
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]554<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]555you want to test those</p>
556<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]557 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
558 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]559 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
560 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]561 <li>(seeems working but delayed from release) parsing/import of Docbook
562 SGML docs</li>
563</ul>
564
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]565<h3>2.4.6: Oct 10 2001</h3>
566<ul>
567 <li>added and updated man pages by John Fleck</li>
568 <li>portability and configure fixes</li>
569 <li>an infinite loop on the HTML parser was removed (William)</li>
570 <li>Windows makefile patches from Igor</li>
571 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
572 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
573</ul>
574
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]575<h3>2.4.5: Sep 14 2001</h3>
576<ul>
577 <li>Remove a few annoying bugs in 2.4.4</li>
578 <li>forces the HTML serializer to output decimal charrefs since some
579 version of Netscape can't handle hexadecimal ones</li>
580</ul>
581
582<h3>1.8.16: Sep 14 2001</h3>
583<ul>
584 <li>maintenance release of the old libxml1 branch, couple of bug and
585 portability fixes</li>
586</ul>
587
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]588<h3>2.4.4: Sep 12 2001</h3>
589<ul>
590 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
591 Catalog</li>
592 <li>a few bug fixes and some portability changes</li>
593 <li>some documentation cleanups</li>
594</ul>
595
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]596<h3>2.4.3: Aug 23 2001</h3>
597<ul>
598 <li>XML Catalog support see the doc</li>
599 <li>New NaN/Infinity floating point code</li>
600 <li>A few bug fixes</li>
601</ul>
602
603<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]604<ul>
605 <li>adds xmlLineNumbersDefault() to control line number generation</li>
606 <li>lot of bug fixes</li>
607 <li>the Microsoft MSC projects files shuld now be up to date</li>
608 <li>inheritance of namespaces from DTD defaulted attributes</li>
609 <li>fixes a serious potential security bug</li>
610 <li>added a --format option to xmllint</li>
611</ul>
612
613<h3>2.4.1: July 24 2001</h3>
614<ul>
615 <li>possibility to keep line numbers in the tree</li>
616 <li>some computation NaN fixes</li>
617 <li>extension of the XPath API</li>
618 <li>cleanup for alpha and ia64 targets</li>
619 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]620</ul>
621
622<h3>2.4.0: July 10 2001</h3>
623<ul>
624 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
625 <li>Fixed XML Base implementation, added a coupel of examples to the
626 regression tests</li>
627 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]628</ul>
629
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]630<h3>2.3.14: July 5 2001</h3>
631<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]632 <li>fixed some entities problems and reduce mem requirement when
633 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]634 <li>lots of improvements in the XPath queries interpreter can be
635 substancially faster</li>
636 <li>Makefiles and configure cleanups</li>
637 <li>Fixes to XPath variable eval, and compare on empty node set</li>
638 <li>HTML tag closing bug fixed</li>
639 <li>Fixed an URI reference computating problem when validating</li>
640</ul>
641
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]642<h3>2.3.13: June 28 2001</h3>
643<ul>
644 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
645 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
646</ul>
647
648<h3>1.8.14: June 28 2001</h3>
649<ul>
650 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
651 <li>Small Makefile fix</li>
652</ul>
653
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]654<h3>2.3.12: June 26 2001</h3>
655<ul>
656 <li>lots of cleanup</li>
657 <li>a couple of validation fix</li>
658 <li>fixed line number counting</li>
659 <li>fixed serious problems in the XInclude processing</li>
660 <li>added support for UTF8 BOM at beginning of entities</li>
661 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
662 miscompile uri.c (William), Thomas Leitner provided a fix for the
663 optimizer on Tru64</li>
664 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
665 compilation on Windows MSC</li>
666 <li>update of libxml-doc.el (Felix Natter)</li>
667 <li>fixed 2 bugs in URI normalization code</li>
668</ul>
669
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]670<h3>2.3.11: June 17 2001</h3>
671<ul>
672 <li>updates to trio, Makefiles and configure should fix some portability
673 problems (alpha)</li>
674 <li>fixed some HTML serialization problems (pre, script, and block/inline
675 handling), added encoding aware APIs, cleanup of this code</li>
676 <li>added xmlHasNsProp()</li>
677 <li>implemented a specific PI for encoding support in the DocBook SGML
678 parser</li>
679 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
680 node selection)</li>
681 <li>fixed a performance problem and an error in the validation code</li>
682 <li>fixed XInclude routine to implement the recursive behaviour</li>
683 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
684 <li>added --version to xmllint for bug reports</li>
685</ul>
686
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]687<h3>2.3.10: June 1 2001</h3>
688<ul>
689 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]690 <li>a number of reported bugs got fixed, in XPath, iconv detection,
691 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]692 <li>XPath string function should now handle unicode correctly</li>
693</ul>
694
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]695<h3>2.3.9: May 19 2001</h3>
696
697<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
698<ul>
699 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
700 <li>some serious speed optimisation again</li>
701 <li>some documentation cleanups</li>
702 <li>trying to get better linking on solaris (-R)</li>
703 <li>XPath API cleanup from Thomas Broyer</li>
704 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
705 xmlValidGetValidElements()</li>
706 <li>Added an INSTALL file</li>
707 <li>Attribute removal added to API: #54433</li>
708 <li>added a basic support for SGML catalogs</li>
709 <li>fixed xmlKeepBlanksDefault(0) API</li>
710 <li>bugfix in xmlNodeGetLang()</li>
711 <li>fixed a small configure portability problem</li>
712 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
713</ul>
714
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]715<h3>1.8.13: May 14 2001</h3>
716<ul>
717 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
718</ul>
719
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]720<h3>2.3.8: May 3 2001</h3>
721<ul>
722 <li>Integrated an SGML DocBook parser for the Gnome project</li>
723 <li>Fixed a few things in the HTML parser</li>
724 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
725 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]726 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
727 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]728 <li>incorporated more Windows cleanup</li>
729 <li>added xmlSaveFormatFile()</li>
730 <li>fixed problems in copying nodes with entities references (gdome)</li>
731 <li>removed some troubles surrounding the new validation module</li>
732</ul>
733
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]734<h3>2.3.7: April 22 2001</h3>
735<ul>
736 <li>lots of small bug fixes, corrected XPointer</li>
737 <li>Non determinist content model validation support</li>
738 <li>added xmlDocCopyNode for gdome2</li>
739 <li>revamped the way the HTML parser handles end of tags</li>
740 <li>XPath: corrctions of namespacessupport and number formatting</li>
741 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
742 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
743 <li>Improved validation speed sensible for DocBook</li>
744 <li>fixed a big bug with ID declared in external parsed entities</li>
745 <li>portability fixes, update of Trio from Bjorn Reese</li>
746</ul>
747
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]748<h3>2.3.6: April 8 2001</h3>
749<ul>
750 <li>Code cleanup using extreme gcc compiler warning options, found and
751 cleared half a dozen potential problem</li>
752 <li>the Eazel team found an XML parser bug</li>
753 <li>cleaned up the user of some of the string formatting function. used the
754 trio library code to provide the one needed when the platform is missing
755 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]756 <li>xpath: removed a memory leak and fixed the predicate evaluation
757 problem, extended the testsuite and cleaned up the result. XPointer seems
758 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]759</ul>
760
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]761<h3>2.3.5: Mar 23 2001</h3>
762<ul>
763 <li>Biggest change is separate parsing and evaluation of XPath expressions,
764 there is some new APIs for this too</li>
765 <li>included a number of bug fixes(XML push parser, 51876, notations,
766 52299)</li>
767 <li>Fixed some portability issues</li>
768</ul>
769
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]770<h3>2.3.4: Mar 10 2001</h3>
771<ul>
772 <li>Fixed bugs #51860 and #51861</li>
773 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
774 size to be application tunable.</li>
775 <li>Some cleanup in the validation code, still a bug left and this part
776 should probably be rewritten to support ambiguous content model :-\</li>
777 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
778 parser</li>
779 <li>Fixed another bug in xmlNodeGetContent()</li>
780 <li>Bjorn fixed XPath node collection and Number formatting</li>
781 <li>Fixed a loop reported in the HTML parsing</li>
782 <li>blank space are reported even if the Dtd content model proves that they
783 are formatting spaces, this is for XmL conformance</li>
784</ul>
785
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]786<h3>2.3.3: Mar 1 2001</h3>
787<ul>
788 <li>small change in XPath for XSLT</li>
789 <li>documentation cleanups</li>
790 <li>fix in validation by Gary Pennington</li>
791 <li>serious parsing performances improvements</li>
792</ul>
793
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]794<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]795<ul>
796 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
797 <li>fixed a Dtd parsing bug</li>
798 <li>fixed a bug in xmlNodeGetContent</li>
799 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
800</ul>
801
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]802<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]803<ul>
804 <li>some XPath and HTML bug fixes for XSLT</li>
805 <li>small extension of the hash table interfaces for DOM gdome2
806 implementation</li>
807 <li>A few bug fixes</li>
808</ul>
809
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]810<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]811<ul>
812 <li>Lots of XPath bug fixes</li>
813 <li>Add a mode with Dtd lookup but without validation error reporting for
814 XSLT</li>
815 <li>Add support for text node without escaping (XSLT)</li>
816 <li>bug fixes for xmlCheckFilename</li>
817 <li>validation code bug fixes from Gary Pennington</li>
818 <li>Patch from Paul D. Smith correcting URI path normalization</li>
819 <li>Patch to allow simultaneous install of libxml-devel and
820 libxml2-devel</li>
821 <li>the example Makefile is now fixed</li>
822 <li>added HTML to the RPM packages</li>
823 <li>tree copying bugfixes</li>
824 <li>updates to Windows makefiles</li>
825 <li>optimisation patch from Bjorn Reese</li>
826</ul>
827
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]828<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]829<ul>
830 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
831 <li>added htmlHandleOmittedElem()</li>
832 <li>Applied Bjorn Reese's IPV6 first patch</li>
833 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]834 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]835</ul>
836
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]837<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]838<ul>
839 <li>Fix the Windows problems of 2.2.8</li>
840 <li>integrate OpenVMS patches</li>
841 <li>better handling of some nasty HTML input</li>
842 <li>Improved the XPointer implementation</li>
843 <li>integrate a number of provided patches</li>
844</ul>
845
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]846<h3>2.2.9: Nov 25 2000</h3>
847<ul>
848 <li>erroneous release :-(</li>
849</ul>
850
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]851<h3>2.2.8: Nov 13 2000</h3>
852<ul>
853 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
854 support</li>
855 <li>Patch in conditional section handling</li>
856 <li>updated MS compiler project</li>
857 <li>fixed some XPath problems</li>
858 <li>added an URI escaping function</li>
859 <li>some other bug fixes</li>
860</ul>
861
862<h3>2.2.7: Oct 31 2000</h3>
863<ul>
864 <li>added message redirection</li>
865 <li>XPath improvements (thanks TOM !)</li>
866 <li>xmlIOParseDTD() added</li>
867 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
868 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
869</ul>
870
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]871<h3>2.2.6: Oct 25 2000:</h3>
872<ul>
873 <li>Added an hash table module, migrated a number of internal structure to
874 those</li>
875 <li>Fixed a posteriori validation problems</li>
876 <li>HTTP module cleanups</li>
877 <li>HTML parser improvements (tag errors, script/style handling, attribute
878 normalization)</li>
879 <li>coalescing of adjacent text nodes</li>
880 <li>couple of XPath bug fixes, exported the internal API</li>
881</ul>
882
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]883<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]884<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]885 <li>XPointer implementation and testsuite</li>
886 <li>Lot of XPath fixes, added variable and functions registration, more
887 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]888 <li>Portability fixes, lots of enhancements toward an easy Windows build
889 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]890 <li>Late validation fixes</li>
891 <li>Integrated a lot of contributed patches</li>
892 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]893 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]894</ul>
895
896<h3>2.2.4: Oct 1 2000:</h3>
897<ul>
898 <li>main XPath problem fixed</li>
899 <li>Integrated portability patches for Windows</li>
900 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]901</ul>
902
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]903<h3>2.2.3: Sep 17 2000</h3>
904<ul>
905 <li>bug fixes</li>
906 <li>cleanup of entity handling code</li>
907 <li>overall review of all loops in the parsers, all sprintf usage has been
908 checked too</li>
909 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
910 works smoothly now.</li>
911</ul>
912
913<h3>1.8.10: Sep 6 2000</h3>
914<ul>
915 <li>bug fix release for some Gnome projects</li>
916</ul>
917
918<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]919<ul>
920 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]921 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]922</ul>
923
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]924<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]925<ul>
926 <li>a purely bug fixes release</li>
927 <li>fixed an encoding support problem when parsing from a memory block</li>
928 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]929 <li>removed a bug in the function allowing to override the memory
930 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]931</ul>
932
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]933<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]934<ul>
935 <li>applied a lot of portability fixes</li>
936 <li>better encoding support/cleanup and saving (content is now always
937 encoded in UTF-8)</li>
938 <li>the HTML parser now correctly handles encodings</li>
939 <li>added xmlHasProp()</li>
940 <li>fixed a serious problem with &amp;#38;</li>
941 <li>propagated the fix to FTP client</li>
942 <li>cleanup, bugfixes, etc ...</li>
943 <li>Added a page about <a href="encoding.html">libxml Internationalization
944 support</a></li>
945</ul>
946
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]947<h3>1.8.9: July 9 2000</h3>
948<ul>
949 <li>fixed the spec the RPMs should be better</li>
950 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
951 rpmfind users problem</li>
952</ul>
953
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]954<h3>2.1.1: July 1 2000</h3>
955<ul>
956 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
957 <li>improvements on the HTML parser</li>
958</ul>
959
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]960<h3>2.1.0 and 1.8.8: June 29 2000</h3>
961<ul>
962 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
963 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
964 about &amp;#38; charref parsing</li>
965 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
966 also contains numerous fixes and enhancements:
967 <ul>
968 <li>added xmlStopParser() to stop parsing</li>
969 <li>improved a lot parsing speed when there is large CDATA blocs</li>
970 <li>includes XPath patches provided by Picdar Technology</li>
971 <li>tried to fix as much as possible DtD validation and namespace
972 related problems</li>
973 <li>output to a given encoding has been added/tested</li>
974 <li>lot of various fixes</li>
975 </ul>
976 </li>
977</ul>
978
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]979<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]980<ul>
981 <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]982 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
983 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
984 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]985 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]986 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]987 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]988 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]989 <pre>#include "xxx.h"</pre>
990 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]991 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
992 <li>the memory allocation routines used by libxml can now be overloaded
993 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]994 <li>The previously CVS only tool tester has been renamed
995 <strong>xmllint</strong> and is now installed as part of the libxml2
996 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]997 <li>The I/O interface has been revamped. There is now ways to plug in
998 specific I/O modules, either at the URI scheme detection level using
999 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
1000 parser context using xmlCreateIOParserCtxt()</li>
1001 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
1002 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1003 <li>a number of optional features of libxml can now be excluded at
1004 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1005</ul>
1006
1007<h3>2.0.0beta: Mar 14 2000</h3>
1008<ul>
1009 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1010 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1011 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1012 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1013 <li>This version is now the head in the Gnome CVS base, the old one is
1014 available under the tag LIB_XML_1_X</li>
1015 <li>This includes a very large set of changes. Froma programmatic point of
1016 view applications should not have to be modified too much, check the <a
1017 href="upgrade.html">upgrade page</a></li>
1018 <li>Some interfaces may changes (especially a bit about encoding).</li>
1019 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1020 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1021 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1022 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1023 <li>Better handling of entities, especially well formedness checking
1024 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1025 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1026 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1027 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1028 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1029 </ul>
1030 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1031 <li>Serious progress were made toward compliance, <a
1032 href="conf/result.html">here are the result of the test</a> against the
1033 OASIS testsuite (except the japanese tests since I don't support that
1034 encoding yet). This URL is rebuilt every couple of hours using the CVS
1035 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1036</ul>
1037
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1038<h3>1.8.7: Mar 6 2000</h3>
1039<ul>
1040 <li>This is a bug fix release:</li>
1041 <li>It is possible to disable the ignorable blanks heuristic used by
1042 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1043 that for adherence to XML spec, this behaviour will be disabled by
1044 default in 2.x . The same function will allow to keep compatibility for
1045 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1046 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1047 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1048 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1049 compilation on some platforms has been fixed</li>
1050 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1051 URIs</li>
1052</ul>
1053
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1054<h3>1.8.6: Jan 31 2000</h3>
1055<ul>
1056 <li>added a nanoFTP transport module, debugged until the new version of <a
1057 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1058 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1059</ul>
1060
1061<h3>1.8.5: Jan 21 2000</h3>
1062<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1063 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1064 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1065 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1066 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1067 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1068 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1069 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1070 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1071</ul>
1072
1073<h3>1.8.4: Jan 13 2000</h3>
1074<ul>
1075 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1076 <li>all exit() call should have been removed from libxml</li>
1077 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1078 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1079</ul>
1080
1081<h3>1.8.3: Jan 5 2000</h3>
1082<ul>
1083 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1084 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1085 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1086 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1087 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1088 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1089 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1090 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1091 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1092</ul>
1093
1094<h3>1.8.2: Dec 21 1999</h3>
1095<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1096 <li>I got another problem with includes and C++, I hope this issue is fixed
1097 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1098 <li>Added a few tree modification functions: xmlReplaceNode,
1099 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1100 xmlDocSetRootElement</li>
1101 <li>Tried to improve the HTML output with help from <a
1102 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1103</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1104
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1105<h3>1.8.1: Dec 18 1999</h3>
1106<ul>
1107 <li>various patches to avoid troubles when using libxml with C++ compilers
1108 the "namespace" keyword and C escaping in include files</li>
1109 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1110 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1111 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1112 <li>fixed a posteriori validation (validation after parsing, or by using a
1113 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1114 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1115</ul>
1116
1117<h3>1.8.0: Dec 12 1999</h3>
1118<ul>
1119 <li>cleanup, especially memory wise</li>
1120 <li>the parser should be more reliable, especially the HTML one, it should
1121 not crash, whatever the input !</li>
1122 <li>Integrated various patches, especially a speedup improvement for large
1123 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1124 configure with --with-buffers to enable them.</li>
1125 <li>attribute normalization, oops should have been added long ago !</li>
1126 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1127 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1128</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1129
1130<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1131<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1132 <li>Lots of HTML improvement</li>
1133 <li>Fixed some errors when saving both XML and HTML</li>
1134 <li>More examples, the regression tests should now look clean</li>
1135 <li>Fixed a bug with contiguous charref</li>
1136</ul>
1137
1138<h3>1.7.3: Sep 29 1999</h3>
1139<ul>
1140 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1141 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1142 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1143</ul>
1144
1145<h3>1.7.1: Sep 24 1999</h3>
1146<ul>
1147 <li>The basic type for strings manipulated by libxml has been renamed in
1148 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1149 is that CHAR was conflicting with a predefined type on Windows. However
1150 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1151 <strong>#define </strong>.</li>
1152 <li>Changed another error : the use of a structure field called errno, and
1153 leading to troubles on platforms where it's a macro</li>
1154</ul>
1155
1156<h3>1.7.0: sep 23 1999</h3>
1157<ul>
1158 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1159 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1160 <li>Added an errno to report errors by another mean than a simple printf
1161 like callback</li>
1162 <li>Finished ID/IDREF support and checking when validation</li>
1163 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1164 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1165 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1166 implementation</li>
1167 <li>Added an HTML parser front-end</li>
1168</ul>
1169
1170<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1171
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1172<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]1173markup-based structured documents. Here is <a name="example">an example XML
1174document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1175<pre>&lt;?xml version="1.0"?&gt;
1176&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1177 &lt;head&gt;
1178 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1179 &lt;/head&gt;
1180 &lt;chapter&gt;
1181 &lt;title&gt;The Linux adventure&lt;/title&gt;
1182 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1183 &lt;image href="linus.gif"/&gt;
1184 &lt;p&gt;...&lt;/p&gt;
1185 &lt;/chapter&gt;
1186&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1187
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1188<p>The first line specifies that it's an XML document and gives useful
1189information about its encoding. Then the document is a text format whose
1190structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1191to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1192(no content), a single tag can serve as both the opening and closing tag if
1193it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1194that, for example, the image tag has no content (just an attribute) and is
1195closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1196
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1197<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]1198structured document maintenance (where it follows the steps of SGML) to
1199simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1200spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1201it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1202
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1203<h2><a name="XSLT">XSLT</a></h2>
1204
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1205<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1206
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1207<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1208language for transforming XML documents into other XML documents (or
1209HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1210
1211<p>A separate library called libxslt is being built on top of libxml2. This
1212module "libxslt" can be found in the Gnome CVS base too.</p>
1213
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1214<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1215href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1216supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1217href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1218
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1219<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1220
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1221<p>Libxml is made of multiple components; some of them are optional, and most
1222of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1223<ul>
1224 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1225 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1226 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1227 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1228 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1229 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1230 <li>a SAX tree module to build an in-memory DOM representation</li>
1231 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1232 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1233 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1234 (optional)</li>
1235 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1236</ul>
1237
1238<p>Graphically this gives the following:</p>
1239
1240<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1241
1242<p></p>
1243
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1244<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1245
1246<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1247returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1248<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1249as the file name, the document type, and a <strong>children</strong> pointer
1250which is the root of the document (or more exactly the first child under the
1251root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1252chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1253relationship. An xmlNode can also carry properties (a chain of xmlAttr
1254structures). An attribute may have a value which is a list of TEXT or
1255ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1256
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1257<p>Here is an example (erroneous with respect to the XML spec since there
1258should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1259
1260<p><img src="structure.gif" alt=" structure.gif "></p>
1261
1262<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1263called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1264prints them back as parsed. This is useful for detecting errors both in XML
1265code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1266which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1267result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1268<pre>DOCUMENT
1269version=1.0
1270standalone=true
1271 ELEMENT EXAMPLE
1272 ATTRIBUTE prop1
1273 TEXT
1274 content=gnome is great
1275 ATTRIBUTE prop2
1276 ENTITY_REF
1277 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1278 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1279 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1280 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1281 TEXT
1282 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1283 ELEMENT chapter
1284 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1285 TEXT
1286 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1287 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1288 TEXT
1289 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1290 ELEMENT image
1291 ATTRIBUTE href
1292 TEXT
1293 content=linus.gif
1294 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1295 TEXT
1296 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1297
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1298<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1299
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1300<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1301
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1302<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1303memory. 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]1304loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1305a <strong>callback-based interface</strong> to the parser. Before parsing,
1306the application layer registers a customized set of callbacks which are
1307called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1308
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1309<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]1310libxml, see the <a
1311href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1312documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1313Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1314
1315<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1316program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1317binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1318distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1319testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1320<pre>SAX.setDocumentLocator()
1321SAX.startDocument()
1322SAX.getEntity(amp)
1323SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1324SAX.characters( , 3)
1325SAX.startElement(head)
1326SAX.characters( , 4)
1327SAX.startElement(title)
1328SAX.characters(Welcome to Gnome, 16)
1329SAX.endElement(title)
1330SAX.characters( , 3)
1331SAX.endElement(head)
1332SAX.characters( , 3)
1333SAX.startElement(chapter)
1334SAX.characters( , 4)
1335SAX.startElement(title)
1336SAX.characters(The Linux adventure, 19)
1337SAX.endElement(title)
1338SAX.characters( , 4)
1339SAX.startElement(p)
1340SAX.characters(bla bla bla ..., 15)
1341SAX.endElement(p)
1342SAX.characters( , 4)
1343SAX.startElement(image, href='linus.gif')
1344SAX.endElement(image)
1345SAX.characters( , 4)
1346SAX.startElement(p)
1347SAX.characters(..., 3)
1348SAX.endElement(p)
1349SAX.characters( , 3)
1350SAX.endElement(chapter)
1351SAX.characters( , 1)
1352SAX.endElement(EXAMPLE)
1353SAX.endDocument()</pre>
1354
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1355<p>Most of the other interfaces of libxml are based on the DOM tree-building
1356facility, so nearly everything up to the end of this document presupposes the
1357use of the standard DOM tree build. Note that the DOM tree itself is built by
1358a set of registered default callbacks, without internal specific
1359interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1360
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1361<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1362
1363<p>Table of Content:</p>
1364<ol>
1365 <li><a href="#General5">General overview</a></li>
1366 <li><a href="#definition">The definition</a></li>
1367 <li><a href="#Simple">Simple rules</a>
1368 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1369 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1370 <li><a href="#Declaring">Declaring elements</a></li>
1371 <li><a href="#Declaring1">Declaring attributes</a></li>
1372 </ol>
1373 </li>
1374 <li><a href="#Some">Some examples</a></li>
1375 <li><a href="#validate">How to validate</a></li>
1376 <li><a href="#Other">Other resources</a></li>
1377</ol>
1378
1379<h3><a name="General5">General overview</a></h3>
1380
1381<p>Well what is validation and what is a DTD ?</p>
1382
1383<p>DTD is the acronym for Document Type Definition. This is a description of
1384the content for a familly of XML files. This is part of the XML 1.0
1385specification, and alows to describe and check that a given document instance
1386conforms to a set of rules detailing its structure and content.</p>
1387
1388<p>Validation is the process of checking a document against a DTD (more
1389generally against a set of construction rules).</p>
1390
1391<p>The validation process and building DTDs are the two most difficult parts
1392of the XML life cycle. Briefly a DTD defines all the possibles element to be
1393found within your document, what is the formal shape of your document tree
1394(by defining the allowed content of an element, either text, a regular
1395expression for the allowed list of children, or mixed content i.e. both text
1396and children). The DTD also defines the allowed attributes for all elements
1397and the types of the attributes.</p>
1398
1399<h3><a name="definition1">The definition</a></h3>
1400
1401<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1402href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1403Rev1</a>):</p>
1404<ul>
1405 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1406 elements</a></li>
1407 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1408 attributes</a></li>
1409</ul>
1410
1411<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1412ancient...</p>
1413
1414<h3><a name="Simple1">Simple rules</a></h3>
1415
1416<p>Writing DTD can be done in multiple ways, the rules to build them if you
1417need something fixed or something which can evolve over time can be radically
1418different. Really complex DTD like Docbook ones are flexible but quite harder
1419to design. I will just focuse on DTDs for a formats with a fixed simple
1420structure. It is just a set of basic rules, and definitely not exhaustive nor
1421useable for complex DTD design.</p>
1422
1423<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1424
1425<p>Assuming the top element of the document is <code>spec</code> and the dtd
1426is placed in the file <code>mydtd</code> in the subdirectory
1427<code>dtds</code> of the directory from where the document were loaded:</p>
1428
1429<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1430
1431<p>Notes:</p>
1432<ul>
1433 <li>the system string is actually an URI-Reference (as defined in <a
1434 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1435 full URL string indicating the location of your DTD on the Web, this is a
1436 really good thing to do if you want others to validate your document</li>
1437 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1438 magic string) so that the DTd is looked up in catalogs on the client side
1439 without having to locate it on the web</li>
1440 <li>a dtd contains a set of elements and attributes declarations, but they
1441 don't define what the root of the document should be. This is explicitely
1442 told to the parser/validator as the first element of the
1443 <code>DOCTYPE</code> declaration.</li>
1444</ul>
1445
1446<h4><a name="Declaring2">Declaring elements</a>:</h4>
1447
1448<p>The following declares an element <code>spec</code>:</p>
1449
1450<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1451
1452<p>it also expresses that the spec element contains one <code>front</code>,
1453one <code>body</code> and one optionnal <code>back</code> children elements
1454in this order. The declaration of one element of the structure and its
1455content are done in a single declaration. Similary the following declares
1456<code>div1</code> elements:</p>
1457
1458<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1459
1460<p>means div1 contains one <code>head</code> then a series of optional
1461<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1462optional <code>div2</code>. And last but not least an element can contain
1463text:</p>
1464
1465<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1466
1467<p><code>b</code> contains text or being of mixed content (text and elements
1468in no particular order):</p>
1469
1470<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1471
1472<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1473<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1474order.</p>
1475
1476<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1477
1478<p>again the attributes declaration includes their content definition:</p>
1479
1480<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1481
1482<p>means that the element <code>termdef</code> can have a <code>name</code>
1483attribute containing text (<code>CDATA</code>) and which is optionnal
1484(<code>#IMPLIED</code>). The attribute value can also be defined within a
1485set:</p>
1486
1487<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1488"ordered"&gt;</code></p>
1489
1490<p>means <code>list</code> element have a <code>type</code> attribute with 3
1491allowed values "bullets", "ordered" or "glossary" and which default to
1492"ordered" if the attribute is not explicitely specified.</p>
1493
1494<p>The content type of an attribute can be text (<code>CDATA</code>),
1495anchor/reference/references
1496(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1497(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1498(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1499<code>chapter</code> element can have an optional <code>id</code> attribute
1500of type <code>ID</code>, usable for reference from attribute of type
1501IDREF:</p>
1502
1503<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1504
1505<p>The last value of an attribute definition can be <code>#REQUIRED
1506</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1507meaning that it is optional, or the default value (possibly prefixed by
1508<code>#FIXED</code> if it is the only allowed).</p>
1509
1510<p>Notes:</p>
1511<ul>
1512 <li>usually the attributes pertaining to a given element are declared in a
1513 single expression, but it is just a convention adopted by a lot of DTD
1514 writers:
1515 <pre>&lt;!ATTLIST termdef
1516 id ID #REQUIRED
1517 name CDATA #IMPLIED&gt;</pre>
1518 <p>The previous construct defines both <code>id</code> and
1519 <code>name</code> attributes for the element <code>termdef</code></p>
1520 </li>
1521</ul>
1522
1523<h3><a name="Some1">Some examples</a></h3>
1524
1525<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1526contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1527example shows an XML file where the simple DTD is directly included within
1528the document.</p>
1529
1530<h3><a name="validate1">How to validate</a></h3>
1531
1532<p>The simplest is to use the xmllint program comming with libxml. The
1533<code>--valid</code> option turn on validation of the files given as input,
1534for example the following validates a copy of the first revision of the XML
15351.0 specification:</p>
1536
1537<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1538
1539<p>the -- noout is used to not output the resulting tree.</p>
1540
1541<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1542a given DTD.</p>
1543
1544<p>Libxml exports an API to handle DTDs and validation, check the <a
1545href="http://xmlsoft.org/html/libxml-valid.html">associated
1546description</a>.</p>
1547
1548<h3><a name="Other1">Other resources</a></h3>
1549
1550<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1551will just list one for now, others pointers welcome:</p>
1552<ul>
1553 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1554</ul>
1555
1556<p>I suggest looking at the examples found under test/valid/dtd and any of
1557the large number of books available on XML. The dia example in test/valid
1558should be both simple and complete enough to allow you to build your own.</p>
1559
1560<p></p>
1561
1562<h2><a name="Memory">Memory Management</a></h2>
1563
1564<p>Table of Content:</p>
1565<ol>
1566 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1567 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1568 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1569 <li><a href="#Debugging">Debugging routines</a></li>
1570 <li><a href="#General4">General memory requirements</a></li>
1571</ol>
1572
1573<h3><a name="General3">General overview</a></h3>
1574
1575<p>The module <code><a
1576href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1577provides the interfaces to the libxml memory system:</p>
1578<ul>
1579 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1580 xmlMalloc() and xmlRealloc()</li>
1581 <li>those routines can be reallocated to a specific set of routine, by
1582 default the libc ones i.e. free(), malloc() and realloc()</li>
1583 <li>the xmlmemory.c module includes a set of debugging routine</li>
1584</ul>
1585
1586<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1587
1588<p>It is sometimes useful to not use the default memory allocator, either for
1589debugging, analysis or to implement a specific behaviour on memory management
1590(like on embedded systems). Two function calls are available to do so:</p>
1591<ul>
1592 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1593 which return the current set of functions in use by the parser</li>
1594 <li><a
1595 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1596 which allow to set up a new set of memory allocation functions</li>
1597</ul>
1598
1599<p>Of course a call to xmlMemSetup() should probably be done before calling
1600any other libxml routines (unless you are sure your allocations routines are
1601compatibles).</p>
1602
1603<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1604
1605<p>Libxml is not stateless, there is a few set of memory structures needing
1606allocation before the parser is fully functionnal (some encoding structures
1607for example). This also mean that once parsing is finished there is a tiny
1608amount of memory (a few hundred bytes) which can be recollected if you don't
1609reuse the parser immediately:</p>
1610<ul>
1611 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1612 ()</a>
1613 is a centralized routine to free the parsing states. Note that it won't
1614 deallocate any produced tree if any (use the xmlFreeDoc() and related
1615 routines for this).</li>
1616 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1617 ()</a>
1618 is the dual routine allowing to preallocate the parsing state which can
1619 be useful for example to avoid initialization reentrancy problems when
1620 using libxml in multithreaded applications</li>
1621</ul>
1622
1623<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1624at the next invocation of parser routines, but be careful of the consequences
1625in multithreaded applications.</p>
1626
1627<h3><a name="Debugging">Debugging routines</a></h3>
1628
1629<p>When configured using --with-mem-debug flag (off by default), libxml uses
1630a set of memory allocation debugging routineskeeping track of all allocated
1631blocks and the location in the code where the routine was called. A couple of
1632other debugging routines allow to dump the memory allocated infos to a file
1633or call a specific routine when a given block number is allocated:</p>
1634<ul>
1635 <li><a
1636 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1637 <a
1638 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1639 and <a
1640 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1641 are the memory debugging replacement allocation routines</li>
1642 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1643 ()</a>
1644 dumps all the informations about the allocated memory block lefts in the
1645 <code>.memdump</code> file</li>
1646</ul>
1647
1648<p>When developping libxml memory debug is enabled, the tests programs call
1649xmlMemoryDump () and the "make test" regression tests will check for any
1650memory leak during the full regression test sequence, this helps a lot
1651ensuring that libxml does not leak memory and bullet proof memory
1652allocations use (some libc implementations are known to be far too permissive
1653resulting in major portability problems!).</p>
1654
1655<p>If the .memdump reports a leak, it displays the allocation function and
1656also tries to give some informations about the content and structure of the
1657allocated blocks left. This is sufficient in most cases to find the culprit,
1658but not always. Assuming the allocation problem is reproductible, it is
1659possible to find more easilly:</p>
1660<ol>
1661 <li>write down the block number xxxx not allocated</li>
1662 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1663 <li>run the program under a debugger and set a breakpoint on
1664 xmlMallocBreakpoint() a specific function called when this precise block
1665 is allocated</li>
1666 <li>when the breakpoint is reached you can then do a fine analysis of the
1667 allocation an step to see the condition resulting in the missing
1668 deallocation.</li>
1669</ol>
1670
1671<p>I used to use a commercial tool to debug libxml memory problems but after
1672noticing that it was not detecting memory leaks that simple mechanism was
1673used and proved extremely efficient until now.</p>
1674
1675<h3><a name="General4">General memory requirements</a></h3>
1676
1677<p>How much libxml memory require ? It's hard to tell in average it depends
1678of a number of things:</p>
1679<ul>
1680 <li>the parser itself should work in a fixed amout of memory, except for
1681 information maintained about the stacks of names and entities locations.
1682 The I/O and encoding handlers will probably account for a few KBytes.
1683 This is true for both the XML and HTML parser (though the HTML parser
1684 need more state).</li>
1685 <li>If you are generating the DOM tree then memory requirements will grow
1686 nearly lineary with the size of the data. In general for a balanced
1687 textual document the internal memory requirement is about 4 times the
1688 size of the UTF8 serialization of this document (exmple the XML-1.0
1689 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1690 memory when parsed). Validation will add a amount of memory required for
1691 maintaining the external Dtd state which should be linear with the
1692 complexity of the content model defined by the Dtd</li>
1693 <li>If you don't care about the advanced features of libxml like
1694 validation, DOM, XPath or XPointer, but really need to work fixed memory
1695 requirements, then the SAX interface should be used.</li>
1696</ul>
1697
1698<p></p>
1699
1700<h2><a name="Encodings">Encodings support</a></h2>
1701
1702<p>Table of Content:</p>
1703<ol>
1704 <li><a href="encoding.html#What">What does internationalization support
1705 mean ?</a></li>
1706 <li><a href="encoding.html#internal">The internal encoding, how and
1707 why</a></li>
1708 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1709 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1710 <li><a href="encoding.html#extend">How to extend the existing
1711 support</a></li>
1712</ol>
1713
1714<h3><a name="What">What does internationalization support mean ?</a></h3>
1715
1716<p>XML was designed from the start to allow the support of any character set
1717by using Unicode. Any conformant XML parser has to support the UTF-8 and
1718UTF-16 default encodings which can both express the full unicode ranges. UTF8
1719is a variable length encoding whose greatest point are to resuse the same
1720emcoding for ASCII and to save space for Western encodings, but it is a bit
1721more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1722sometimes combines two pairs), it makes implementation easier, but looks a
1723bit overkill for Western languages encoding. Moreover the XML specification
1724allows document to be encoded in other encodings at the condition that they
1725are clearly labelled as such. For example the following is a wellformed XML
1726document encoded in ISO-8859 1 and using accentuated letter that we French
1727likes for both markup and content:</p>
1728<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1729&lt;très&gt;là&lt;/très&gt;</pre>
1730
1731<p>Having internationalization support in libxml means the foolowing:</p>
1732<ul>
1733 <li>the document is properly parsed</li>
1734 <li>informations about it's encoding are saved</li>
1735 <li>it can be modified</li>
1736 <li>it can be saved in its original encoding</li>
1737 <li>it can also be saved in another encoding supported by libxml (for
1738 example straight UTF8 or even an ASCII form)</li>
1739</ul>
1740
1741<p>Another very important point is that the whole libxml API, with the
1742exception of a few routines to read with a specific encoding or save to a
1743specific encoding, is completely agnostic about the original encoding of the
1744document.</p>
1745
1746<p>It should be noted too that the HTML parser embedded in libxml now obbey
1747the same rules too, the following document will be (as of 2.2.2) handled in
1748an internationalized fashion by libxml too:</p>
1749<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1750 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1751&lt;html lang="fr"&gt;
1752&lt;head&gt;
1753 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1754&lt;/head&gt;
1755&lt;body&gt;
1756&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1757&lt;/html&gt;</pre>
1758
1759<h3><a name="internal">The internal encoding, how and why</a></h3>
1760
1761<p>One of the core decision was to force all documents to be converted to a
1762default internal encoding, and that encoding to be UTF-8, here are the
1763rationale for those choices:</p>
1764<ul>
1765 <li>keeping the native encoding in the internal form would force the libxml
1766 users (or the code associated) to be fully aware of the encoding of the
1767 original document, for examples when adding a text node to a document,
1768 the content would have to be provided in the document encoding, i.e. the
1769 client code would have to check it before hand, make sure it's conformant
1770 to the encoding, etc ... Very hard in practice, though in some specific
1771 cases this may make sense.</li>
1772 <li>the second decision was which encoding. From the XML spec only UTF8 and
1773 UTF16 really makes sense as being the two only encodings for which there
1774 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1775 considered an intelligent choice too since it's a direct Unicode mapping
1776 support. I selected UTF-8 on the basis of efficiency and compatibility
1777 with surrounding software:
1778 <ul>
1779 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1780 more costly to import and export CPU wise) is also far more compact
1781 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1782 for right now (RPM RDF catalogs, advogato data, various configuration
1783 file formats, etc.) and the key point for today's computer
1784 architecture is efficient uses of caches. If one nearly double the
1785 memory requirement to store the same amount of data, this will trash
1786 caches (main memory/external caches/internal caches) and my take is
1787 that this harms the system far more than the CPU requirements needed
1788 for the conversion to UTF-8</li>
1789 <li>Most of libxml version 1 users were using it with straight ASCII
1790 most of the time, doing the conversion with an internal encoding
1791 requiring all their code to be rewritten was a serious show-stopper
1792 for using UTF-16 or UCS-4.</li>
1793 <li>UTF-8 is being used as the de-facto internal encoding standard for
1794 related code like the <a href="http://www.pango.org/">pango</a>
1795 upcoming Gnome text widget, and a lot of Unix code (yep another place
1796 where Unix programmer base takes a different approach from Microsoft
1797 - they are using UTF-16)</li>
1798 </ul>
1799 </li>
1800</ul>
1801
1802<p>What does this mean in practice for the libxml user:</p>
1803<ul>
1804 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1805 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1806 is simply to append 0 byte, as usual.</li>
1807 <li>One just need to make sure that when using chars outside the ASCII set,
1808 the values has been properly converted to UTF-8</li>
1809</ul>
1810
1811<h3><a name="implemente">How is it implemented ?</a></h3>
1812
1813<p>Let's describe how all this works within libxml, basically the I18N
1814(internationalization) support get triggered only during I/O operation, i.e.
1815when reading a document or saving one. Let's look first at the reading
1816sequence:</p>
1817<ol>
1818 <li>when a document is processed, we usually don't know the encoding, a
1819 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1820 ASCII range (0-0x7F) maps with ASCII</li>
1821 <li>the xml declaration if available is parsed, including the encoding
1822 declaration. At that point, if the autodetected encoding is different
1823 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1824 <li>If there is no encoding declaration, then the input has to be in either
1825 UTF-8 or UTF-16, if it is not then at some point when processing the
1826 input, the converter/checker of UTF-8 form will raise an encoding error.
1827 You may end-up with a garbled document, or no document at all ! Example:
1828 <pre>~/XML -&gt; ./xmllint err.xml
1829err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1830&lt;très&gt;là&lt;/très&gt;
1831 ^
1832err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1833&lt;très&gt;là&lt;/très&gt;
1834 ^</pre>
1835 </li>
1836 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1837 then search the default registered encoding converters for that encoding.
1838 If it's not within the default set and iconv() support has been compiled
1839 it, it will ask iconv for such an encoder. If this fails then the parser
1840 will report an error and stops processing:
1841 <pre>~/XML -&gt; ./xmllint err2.xml
1842err2.xml:1: error: Unsupported encoding UnsupportedEnc
1843&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1844 ^</pre>
1845 </li>
1846 <li>From that point the encoder process progressingly the input (it is
1847 plugged as a front-end to the I/O module) for that entity. It captures
1848 and convert on-the-fly the document to be parsed to UTF-8. The parser
1849 itself just does UTF-8 checking of this input and process it
1850 transparently. The only difference is that the encoding information has
1851 been added to the parsing context (more precisely to the input
1852 corresponding to this entity).</li>
1853 <li>The result (when using DOM) is an internal form completely in UTF-8
1854 with just an encoding information on the document node.</li>
1855</ol>
1856
1857<p>Ok then what's happen when saving the document (assuming you
1858colllected/built an xmlDoc DOM like structure) ? It depends on the function
1859called, xmlSaveFile() will just try to save in the original encoding, while
1860xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1861encoding:</p>
1862<ol>
1863 <li>if no encoding is given, libxml will look for an encoding value
1864 associated to the document and if it exists will try to save to that
1865 encoding,
1866 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1867 </li>
1868 <li>so if an encoding was specified, either at the API level or on the
1869 document, libxml will again canonalize the encoding name, lookup for a
1870 converter in the registered set or through iconv. If not found the
1871 function will return an error code</li>
1872 <li>the converter is placed before the I/O buffer layer, as another kind of
1873 buffer, then libxml will simply push the UTF-8 serialization to through
1874 that buffer, which will then progressively be converted and pushed onto
1875 the I/O layer.</li>
1876 <li>It is possible that the converter code fails on some input, for example
1877 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1878 ISO-8859-1 converter won't work. Since the encoders are progressive they
1879 will just report the error and the number of bytes converted, at that
1880 point libxml will decode the offending character, remove it from the
1881 buffer and replace it with the associated charRef encoding &amp;#123; and
1882 resume the convertion. This guarante that any document will be saved
1883 without losses (except for markup names where this is not legal, this is
1884 a problem in the current version, in pactice avoid using non-ascci
1885 characters for tags or attributes names @@). A special "ascii" encoding
1886 name is used to save documents to a pure ascii form can be used when
1887 portability is really crucial</li>
1888</ol>
1889
1890<p>Here is a few examples based on the same test document:</p>
1891<pre>~/XML -&gt; ./xmllint isolat1
1892&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1893&lt;très&gt;là&lt;/très&gt;
1894~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1895&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1896&lt;très&gt;là  &lt;/très&gt;
1897~/XML -&gt; </pre>
1898
1899<p>The same processing is applied (and reuse most of the code) for HTML I18N
1900processing. Looking up and modifying the content encoding is a bit more
1901difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1902so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1903been provided. The parser also attempts to switch encoding on the fly when
1904detecting such a tag on input. Except for that the processing is the same
1905(and again reuses the same code).</p>
1906
1907<h3><a name="Default">Default supported encodings</a></h3>
1908
1909<p>libxml has a set of default converters for the following encodings
1910(located in encoding.c):</p>
1911<ol>
1912 <li>UTF-8 is supported by default (null handlers)</li>
1913 <li>UTF-16, both little and big endian</li>
1914 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1915 <li>ASCII, useful mostly for saving</li>
1916 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1917 predefined entities like &amp;copy; for the Copyright sign.</li>
1918</ol>
1919
1920<p>More over when compiled on an Unix platfor with iconv support the full set
1921of encodings supported by iconv can be instantly be used by libxml. On a
1922linux machine with glibc-2.1 the list of supported encodings and aliases fill
19233 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1924various Japanese ones.</p>
1925
1926<h4>Encoding aliases</h4>
1927
1928<p>From 2.2.3, libxml has support to register encoding names aliases. The
1929goal is to be able to parse document whose encoding is supported but where
1930the name differs (for example from the default set of names accepted by
1931iconv). The following functions allow to register and handle new aliases for
1932existing encodings. Once registered libxml will automatically lookup the
1933aliases when handling a document:</p>
1934<ul>
1935 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1936 <li>int xmlDelEncodingAlias(const char *alias);</li>
1937 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1938 <li>void xmlCleanupEncodingAliases(void);</li>
1939</ul>
1940
1941<h3><a name="extend">How to extend the existing support</a></h3>
1942
1943<p>Well adding support for new encoding, or overriding one of the encoders
1944(assuming it is buggy) should not be hard, just write an input and output
1945conversion routines to/from UTF-8, and register them using
1946xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1947called automatically if the parser(s) encounter such an encoding name
1948(register it uppercase, this will help). The description of the encoders,
1949their arguments and expected return values are described in the encoding.h
1950header.</p>
1951
1952<p>A quick note on the topic of subverting the parser to use a different
1953internal encoding than UTF-8, in some case people will absolutely want to
1954keep the internal encoding different, I think it's still possible (but the
1955encoding must be compliant with ASCII on the same subrange) though I didn't
1956tried it. The key is to override the default conversion routines (by
1957registering null encoders/decoders for your charsets), and bypass the UTF-8
1958checking of the parser by setting the parser context charset
1959(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
1960there is no guarantee taht this will work. You may also have some troubles
1961saving back.</p>
1962
1963<p>Basically proper I18N support is important, this requires at least
1964libxml-2.0.0, but a lot of features and corrections are really available only
1965starting 2.2.</p>
1966
1967<h2><a name="IO">I/O Interfaces</a></h2>
1968
1969<p>Table of Content:</p>
1970<ol>
1971 <li><a href="#General1">General overview</a></li>
1972 <li><a href="#basic">The basic buffer type</a></li>
1973 <li><a href="#Input">Input I/O handlers</a></li>
1974 <li><a href="#Output">Output I/O handlers</a></li>
1975 <li><a href="#entities">The entities loader</a></li>
1976 <li><a href="#Example2">Example of customized I/O</a></li>
1977</ol>
1978
1979<h3><a name="General1">General overview</a></h3>
1980
1981<p>The module <code><a
1982href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
1983the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
1984<ul>
1985 <li>Entities loader, this is a routine which tries to fetch the entities
1986 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
1987 don't look at the public identifier since libxml do not maintain a
1988 catalog. You can redefine you own entity loader by using
1989 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1990 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
1991 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1992 <li>Input I/O buffers which are a commodity structure used by the parser(s)
1993 input layer to handle fetching the informations to feed the parser. This
1994 provides buffering and is also a placeholder where the encoding
1995 convertors to UTF8 are piggy-backed.</li>
1996 <li>Output I/O buffers are similar to the Input ones and fulfill similar
1997 task but when generating a serialization from a tree.</li>
1998 <li>A mechanism to register sets of I/O callbacks and associate them with
1999 specific naming schemes like the protocol part of the URIs.
2000 <p>This affect the default I/O operations and allows to use specific I/O
2001 handlers for certain names.</p>
2002 </li>
2003</ul>
2004
2005<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2006example in the HTML parser is the following:</p>
2007<ol>
2008 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2009 the parsing context and the URI string.</li>
2010 <li>the URI string is checked against the existing registered handlers
2011 using their match() callback function, if the HTTP module was compiled
2012 in, it is registered and its match() function will succeeds</li>
2013 <li>the open() function of the handler is called and if successful will
2014 return an I/O Input buffer</li>
2015 <li>the parser will the start reading from this buffer and progressively
2016 fetch information from the resource, calling the read() function of the
2017 handler until the resource is exhausted</li>
2018 <li>if an encoding change is detected it will be installed on the input
2019 buffer, providing buffering and efficient use of the conversion
2020 routines</li>
2021 <li>once the parser has finished, the close() function of the handler is
2022 called once and the Input buffer and associed resources are
2023 deallocated.</li>
2024</ol>
2025
2026<p>The user defined callbacks are checked first to allow overriding of the
2027default libxml I/O routines.</p>
2028
2029<h3><a name="basic">The basic buffer type</a></h3>
2030
2031<p>All the buffer manipulation handling is done using the
2032<code>xmlBuffer</code> type define in <code><a
2033href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2034resizable memory buffer. The buffer allocation strategy can be selected to be
2035either best-fit or use an exponential doubling one (CPU vs. memory use
2036tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2037<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2038system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2039of functions allows to manipulate buffers with names starting with the
2040<code>xmlBuffer...</code> prefix.</p>
2041
2042<h3><a name="Input">Input I/O handlers</a></h3>
2043
2044<p>An Input I/O handler is a simple structure
2045<code>xmlParserInputBuffer</code> containing a context associated to the
2046resource (file descriptor, or pointer to a protocol handler), the read() and
2047close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2048encoding handler are also present to support charset conversion when
2049needed.</p>
2050
2051<h3><a name="Output">Output I/O handlers</a></h3>
2052
2053<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2054Input one except the callbacks are write() and close().</p>
2055
2056<h3><a name="entities">The entities loader</a></h3>
2057
2058<p>The entity loader resolves requests for new entities and create inputs for
2059the parser. Creating an input from a filename or an URI string is done
2060through the xmlNewInputFromFile() routine. The default entity loader do not
2061handle the PUBLIC identifier associated with an entity (if any). So it just
2062calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2063XML).</p>
2064
2065<p>If you want to hook up a catalog mechanism then you simply need to
2066override the default entity loader, here is an example:</p>
2067<pre>#include &lt;libxml/xmlIO.h&gt;
2068
2069xmlExternalEntityLoader defaultLoader = NULL;
2070
2071xmlParserInputPtr
2072xmlMyExternalEntityLoader(const char *URL, const char *ID,
2073 xmlParserCtxtPtr ctxt) {
2074 xmlParserInputPtr ret;
2075 const char *fileID = NULL;
2076 /* lookup for the fileID depending on ID */
2077
2078 ret = xmlNewInputFromFile(ctxt, fileID);
2079 if (ret != NULL)
2080 return(ret);
2081 if (defaultLoader != NULL)
2082 ret = defaultLoader(URL, ID, ctxt);
2083 return(ret);
2084}
2085
2086int main(..) {
2087 ...
2088
2089 /*
2090 * Install our own entity loader
2091 */
2092 defaultLoader = xmlGetExternalEntityLoader();
2093 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2094
2095 ...
2096}</pre>
2097
2098<h3><a name="Example2">Example of customized I/O</a></h3>
2099
2100<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2101real use case</a>, xmlDocDump() closes the FILE * passed by the application
2102and this was a problem. The <a
2103href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2104new output handler with the closing call deactivated:</p>
2105<ol>
2106 <li>First define a new I/O ouput allocator where the output don't close the
2107 file:
2108 <pre>xmlOutputBufferPtr
2109xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2110    xmlOutputBufferPtr ret;
2111    
2112    if (xmlOutputCallbackInitialized == 0)
2113        xmlRegisterDefaultOutputCallbacks();
2114
2115    if (file == NULL) return(NULL);
2116    ret = xmlAllocOutputBuffer(encoder);
2117    if (ret != NULL) {
2118        ret-&gt;context = file;
2119        ret-&gt;writecallback = xmlFileWrite;
2120        ret-&gt;closecallback = NULL; /* No close callback */
2121    }
2122    return(ret); <br>
2123
2124
2125
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2126
2127
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame^]2128
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2129} </pre>
2130 </li>
2131 <li>And then use it to save the document:
2132 <pre>FILE *f;
2133xmlOutputBufferPtr output;
2134xmlDocPtr doc;
2135int res;
2136
2137f = ...
2138doc = ....
2139
2140output = xmlOutputBufferCreateOwn(f, NULL);
2141res = xmlSaveFileTo(output, doc, NULL);
2142 </pre>
2143 </li>
2144</ol>
2145
2146<h2><a name="Catalog">Catalog support</a></h2>
2147
2148<p>Table of Content:</p>
2149<ol>
2150 <li><a href="General2">General overview</a></li>
2151 <li><a href="#definition">The definition</a></li>
2152 <li><a href="#Simple">Using catalogs</a></li>
2153 <li><a href="#Some">Some examples</a></li>
2154 <li><a href="#reference">How to tune catalog usage</a></li>
2155 <li><a href="#validate">How to debug catalog processing</a></li>
2156 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2157 <li><a href="#implemento">The implementor corner quick review of the
2158 API</a></li>
2159 <li><a href="#Other">Other resources</a></li>
2160</ol>
2161
2162<h3><a name="General2">General overview</a></h3>
2163
2164<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2165(a file or a remote resource) references another entity. The catalog lookup
2166is inserted between the moment the reference is recognized by the software
2167(XML parser, stylesheet processing, or even images referenced for inclusion
2168in a rendering) and the time where loading that resource is actually
2169started.</p>
2170
2171<p>It is basically used for 3 things:</p>
2172<ul>
2173 <li>mapping from "logical" names, the public identifiers and a more
2174 concrete name usable for download (and URI). For example it can associate
2175 the logical name
2176 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2177 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2178 downloaded</p>
2179 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2180 </li>
2181 <li>remapping from a given URL to another one, like an HTTP indirection
2182 saying that
2183 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2184 <p>should really be looked at</p>
2185 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2186 </li>
2187 <li>providing a local cache mechanism allowing to load the entities
2188 associated to public identifiers or remote resources, this is a really
2189 important feature for any significant deployment of XML or SGML since it
2190 allows to avoid the aleas and delays associated to fetching remote
2191 resources.</li>
2192</ul>
2193
2194<h3><a name="definition">The definitions</a></h3>
2195
2196<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2197<ul>
2198 <li>the older SGML catalogs, the official spec is SGML Open Technical
2199 Resolution TR9401:1997, but is better understood by reading <a
2200 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2201 James Clark. This is relatively old and not the preferred mode of
2202 operation of libxml.</li>
2203 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2204 Catalogs</a>
2205 is far more flexible, more recent, uses an XML syntax and should scale
2206 quite better. This is the default option of libxml.</li>
2207</ul>
2208
2209<p></p>
2210
2211<h3><a name="Simple">Using catalog</a></h3>
2212
2213<p>In a normal environment libxml will by default check the presence of a
2214catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2215the processing is completely transparent to the document user. To take a
2216concrete example, suppose you are authoring a DocBook document, this one
2217starts with the following DOCTYPE definition:</p>
2218<pre>&lt;?xml version='1.0'?&gt;
2219&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2220 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2221
2222<p>When validating the document with libxml, the catalog will be
2223automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2224DocBk XML V3.1.4//EN" and the system identifier
2225"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2226been installed on your system and the catalogs actually point to them, libxml
2227will fetch them from the local disk.</p>
2228
2229<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2230DOCTYPE example it's a really old version, but is fine as an example.</p>
2231
2232<p>Libxml will check the catalog each time that it is requested to load an
2233entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2234your system is correctly configured all the authoring phase and processing
2235should use only local files, even if your document stays portable because it
2236uses the canonical public and system ID, referencing the remote document.</p>
2237
2238<h3><a name="Some">Some examples:</a></h3>
2239
2240<p>Here is a couple of fragments from XML Catalogs used in libxml early
2241regression tests in <code>test/catalogs</code> :</p>
2242<pre>&lt;?xml version="1.0"?&gt;
2243&lt;!DOCTYPE catalog PUBLIC
2244 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2245 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2246&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2247 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2248 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2249...</pre>
2250
2251<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2252written in XML, there is a specific namespace for catalog elements
2253"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2254catalog is a <code>public</code> mapping it allows to associate a Public
2255Identifier with an URI.</p>
2256<pre>...
2257 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2258 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2259...</pre>
2260
2261<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2262any URI starting with a given prefix should be looked at another URI
2263constructed by replacing the prefix with an new one. In effect this acts like
2264a cache system for a full area of the Web. In practice it is extremely useful
2265with a file prefix if you have installed a copy of those resources on your
2266local system.</p>
2267<pre>...
2268&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2269 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2270&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2271 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2272&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2273 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2274&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2275 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2276&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2277 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2278...</pre>
2279
2280<p>Delegation is the core features which allows to build a tree of catalogs,
2281easier to maintain than a single catalog, based on Public Identifier, System
2282Identifier or URI prefixes it instructs the catalog software to look up
2283entries in another resource. This feature allow to build hierarchies of
2284catalogs, the set of entries presented should be sufficient to redirect the
2285resolution of all DocBook references to the specific catalog in
2286<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2287references for DocBook 4.2.1 to a specific catalog installed at the same time
2288as the DocBook resources on the local machine.</p>
2289
2290<h3><a name="reference">How to tune catalog usage:</a></h3>
2291
2292<p>The user can change the default catalog behaviour by redirecting queries
2293to its own set of catalogs, this can be done by setting the
2294<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2295empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2296default catalog</p>
2297
2298<h3><a name="validate">How to debug catalog processing:</a></h3>
2299
2300<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2301make libxml output debugging informations for each catalog operations, for
2302example:</p>
2303<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2304warning: failed to load external entity "title.xml"
2305orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2306orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2307Failed to parse catalog /etc/xml/catalog
2308Failed to parse catalog /etc/xml/catalog
2309warning: failed to load external entity "title.xml"
2310Catalogs cleanup
2311orchis:~/XML -&gt; </pre>
2312
2313<p>The test/ent2 references an entity, running the parser from memory makes
2314the base URI unavailable and the the "title.xml" entity cannot be loaded.
2315Setting up the debug environment variable allows to detect that an attempt is
2316made to load the <code>/etc/xml/catalog</code> but since it's not present the
2317resolution fails.</p>
2318
2319<p>But the most advanced way to debug XML catalog processing is to use the
2320<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2321catalogs and make resolution queries to see what is going on. This is also
2322used for the regression tests:</p>
2323<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2324 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2325http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2326orchis:~/XML -&gt; </pre>
2327
2328<p>For debugging what is going on, adding one -v flags increase the verbosity
2329level to indicate the processing done (adding a second flag also indicate
2330what elements are recognized at parsing):</p>
2331<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2332 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2333Parsing catalog test/catalogs/docbook.xml's content
2334Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2335http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2336Catalogs cleanup
2337orchis:~/XML -&gt; </pre>
2338
2339<p>A shell interface is also available to debug and process multiple queries
2340(and for regression tests):</p>
2341<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2342 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2343&gt; help
2344Commands available:
2345public PublicID: make a PUBLIC identifier lookup
2346system SystemID: make a SYSTEM identifier lookup
2347resolve PublicID SystemID: do a full resolver lookup
2348add 'type' 'orig' 'replace' : add an entry
2349del 'values' : remove values
2350dump: print the current catalog state
2351debug: increase the verbosity level
2352quiet: decrease the verbosity level
2353exit: quit the shell
2354&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2355http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2356&gt; quit
2357orchis:~/XML -&gt; </pre>
2358
2359<p>This should be sufficient for most debugging purpose, this was actually
2360used heavily to debug the XML Catalog implementation itself.</p>
2361
2362<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2363
2364<p>Basically XML Catalogs are XML files, you can either use XML tools to
2365manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2366to create a catalog the -create option provide this facility:</p>
2367<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2368&lt;?xml version="1.0"?&gt;
2369&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2370 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2371&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2372orchis:~/XML -&gt; </pre>
2373
2374<p>By default xmlcatalog does not overwrite the original catalog and save the
2375result on the standard output, this can be overridden using the -noout
2376option. The <code>-add</code> command allows to add entries in the
2377catalog:</p>
2378<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2379 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2380 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2381orchis:~/XML -&gt; cat tst.xml
2382&lt;?xml version="1.0"?&gt;
2383&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2384 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2385&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2386&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2387 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2388&lt;/catalog&gt;
2389orchis:~/XML -&gt; </pre>
2390
2391<p>The <code>-add</code> option will always take 3 parameters even if some of
2392the XML Catalog constructs (like nextCatalog) will have only a single
2393argument, just pass a third empty string, it will be ignored.</p>
2394
2395<p>Similarly the <code>-del</code> option remove matching entries from the
2396catalog:</p>
2397<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2398 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2399&lt;?xml version="1.0"?&gt;
2400&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2401 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2402&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2403orchis:~/XML -&gt; </pre>
2404
2405<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2406exact and would have worked in a similar fashion with the Public ID
2407string.</p>
2408
2409<p>This is rudimentary but should be sufficient to manage a not too complex
2410catalog tree of resources.</p>
2411
2412<h3><a name="implemento">The implementor corner quick review of the
2413API:</a></h3>
2414
2415<p>First, and like for every other module of libxml, there is an
2416automatically generated <a href="html/libxml-catalog.html">API page for
2417catalog support</a>.</p>
2418
2419<p>The header for the catalog interfaces should be included as:</p>
2420<pre>#include &lt;libxml/catalog.h&gt;</pre>
2421
2422<p>The API is voluntarily kept very simple. First it is not obvious that
2423applications really need access to it since it is the default behaviour of
2424libxml (Note: it is possible to completely override libxml default catalog by
2425using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2426plug an application specific resolver).</p>
2427
2428<p>Basically libxml support 2 catalog lists:</p>
2429<ul>
2430 <li>the default one, global shared by all the application</li>
2431 <li>a per-document catalog, this one is built if the document uses the
2432 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2433 associated to the parser context and destroyed when the parsing context
2434 is destroyed.</li>
2435</ul>
2436
2437<p>the document one will be used first if it exists.</p>
2438
2439<h4>Initialization routines:</h4>
2440
2441<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2442used at startup to initialize the catalog, if the catalog should be
2443initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2444should be called before xmlInitializeCatalog() which would otherwise do a
2445default initialization first.</p>
2446
2447<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2448own catalog list if needed.</p>
2449
2450<h4>Preferences setup:</h4>
2451
2452<p>The XML Catalog spec requires the possibility to select default
2453preferences between public and system delegation,
2454xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2455xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2456be forbidden, allowed for global catalog, for document catalog or both, the
2457default is to allow both.</p>
2458
2459<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2460(through the xmlGenericError() mechanism).</p>
2461
2462<h4>Querying routines:</h4>
2463
2464<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2465and xmlCatalogResolveURI() are relatively explicit if you read the XML
2466Catalog specification they correspond to section 7 algorithms, they should
2467also work if you have loaded an SGML catalog with a simplified semantic.</p>
2468
2469<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2470operate on the document catalog list</p>
2471
2472<h4>Cleanup and Miscellaneous:</h4>
2473
2474<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2475the per-document equivalent.</p>
2476
2477<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2478first catalog in the global list, and xmlCatalogDump() allows to dump a
2479catalog state, those routines are primarily designed for xmlcatalog, I'm not
2480sure that exposing more complex interfaces (like navigation ones) would be
2481really useful.</p>
2482
2483<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2484it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2485provided because this functionality may be useful for client tools.</p>
2486
2487<h4>threaded environments:</h4>
2488
2489<p>Since the catalog tree is built progressively, some care has been taken to
2490try to avoid troubles in multithreaded environments. The code is now thread
2491safe assuming that the libxml library has been compiled with threads
2492support.</p>
2493
2494<p></p>
2495
2496<h3><a name="Other">Other resources</a></h3>
2497
2498<p>The XML Catalog specification is relatively recent so there isn't much
2499literature to point at:</p>
2500<ul>
2501 <li>You can find an good rant from Norm Walsh about <a
2502 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2503 need for catalogs</a>, it provides a lot of context informations even if
2504 I don't agree with everything presented.</li>
2505 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2506 catalog proposal</a> from John Cowan</li>
2507 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2508 Language</a> (RDDL) another catalog system but more oriented toward
2509 providing metadata for XML namespaces.</li>
2510 <li>the page from the OASIS Technical <a
2511 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2512 Resolution</a> who maintains XML Catalog, you will find pointers to the
2513 specification update, some background and pointers to others tools
2514 providing XML Catalog support</li>
2515 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2516 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2517 work fine for me</li>
2518 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2519 manual page</a></li>
2520</ul>
2521
2522<p>If you have suggestions for corrections or additions, simply contact
2523me:</p>
2524
2525<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2526
2527<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2528using the XML library from the C language. It is not intended to be
2529extensive. I hope the automatically generated documents will provide the
2530completeness required, but as a separate set of documents. The interfaces of
2531the XML library are by principle low level, there is nearly zero abstraction.
2532Those interested in a higher level API should <a href="#DOM">look at
2533DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2534
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2535<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2536separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2537interfaces</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]2538
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2539<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2540
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2541<p>Usually, the first thing to do is to read an XML input. The parser accepts
2542documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2543defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2544<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2545 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2546 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2547 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2548</dl>
2549<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2550 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2551 <dd><p>Parse an XML document contained in a (possibly compressed)
2552 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2553 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2554</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2555
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2556<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]2557failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2558
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2559<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2560
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2561<p>In order for the application to keep the control when the document is
2562being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2563interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2564<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2565 void *user_data,
2566 const char *chunk,
2567 int size,
2568 const char *filename);
2569int xmlParseChunk (xmlParserCtxtPtr ctxt,
2570 const char *chunk,
2571 int size,
2572 int terminate);</pre>
2573
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2574<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2575<pre> FILE *f;
2576
2577 f = fopen(filename, "r");
2578 if (f != NULL) {
2579 int res, size = 1024;
2580 char chars[1024];
2581 xmlParserCtxtPtr ctxt;
2582
2583 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2584 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2585 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2586 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2587 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2588 xmlParseChunk(ctxt, chars, res, 0);
2589 }
2590 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2591 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2592 xmlFreeParserCtxt(ctxt);
2593 }
2594 }</pre>
2595
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2596<p>The HTML parser embedded into libxml also has a push interface; the
2597functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2598
2599<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2600
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2601<p>The tree-building interface makes the parser memory-hungry, first loading
2602the document in memory and then building the tree itself. Reading a document
2603without building the tree is possible using the SAX interfaces (see SAX.h and
2604<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]2605Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2606limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2607<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2608
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2609<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2610
2611<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]2612there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2613also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2614code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2615<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2616 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2617 xmlNodePtr tree, subtree;
2618
2619 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2620 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2621 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2622 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2623 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2624 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2625 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2626 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2627 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2628 subtree = xmlNewChild(tree, NULL, "image", NULL);
2629 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2630
2631<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2632
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2633<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2634
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2635<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2636code has access to the internal structure of all the elements of the tree.
2637The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2638<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2639<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2640example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2641<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2642
2643<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2644<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2645
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2646<p>points to the text node containing the chapter title "The Linux
2647adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2648
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2649<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]2650present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2651to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2652<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2653
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2654<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2655
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2656<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2657is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2658<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2659 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2660 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2661 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2662 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2663 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2664</dl>
2665<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2666 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2667 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2668 <dd><p>This function returns a pointer to new copy of the property
2669 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2670 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2671</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2672
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2673<p>Two functions are provided for reading and writing the text associated
2674with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2675<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2676 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2677 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2678 <dd><p>This function takes an "external" string and converts it to one
2679 text node or possibly to a list of entity and text nodes. All
2680 non-predefined entity references like &amp;Gnome; will be stored
2681 internally as entity nodes, hence the result of the function may not be
2682 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2683 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2684</dl>
2685<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2686 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2687 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2688 <dd><p>This function is the inverse of
2689 <code>xmlStringGetNodeList()</code>. It generates a new string
2690 containing the content of the text and entity nodes. Note the extra
2691 argument inLine. If this argument is set to 1, the function will expand
2692 entity references. For example, instead of returning the &amp;Gnome;
2693 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2694 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2695 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2696</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2697
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2698<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2699
2700<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2701<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2702 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2703 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2704 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2705 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2706</dl>
2707<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2708 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2709 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2710 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2711</dl>
2712<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2713 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2714 <dd><p>Saves the document to a file. In this case, the compression
2715 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2716 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2717</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2718
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2719<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2720
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2721<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2722accesses. The level of compression on saves can be turned on either globally
2723or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2724<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2725 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2726 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2727 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2728</dl>
2729<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2730 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2731 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2732 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2733</dl>
2734<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2735 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2736 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2737 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2738</dl>
2739<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2740 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2741 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2742 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2743</dl>
2744
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2745<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2746
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2747<p>Entities in principle are similar to simple C macros. An entity defines an
2748abbreviation for a given string that you can reuse many times throughout the
2749content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2750may occur frequently within a document, or to confine the change needed to a
2751document to a restricted area in the internal subset of the document (at the
2752beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2753<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27542 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27553 &lt;!ENTITY xml "Extensible Markup Language"&gt;
27564 ]&gt;
27575 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27586 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27597 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2760
2761<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]2762its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2763are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2764predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2765<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2766for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2767<strong>&amp;quot;</strong> for the character '"', and
2768<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2769
2770<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]2771substitute an entity's content so that you can see the replacement text in
2772your application. Or you may prefer to keep entity references as such in the
2773content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2774precious information (if the user went through the pain of explicitly
2775defining entities, he may have a a rather negative attitude if you blindly
2776susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2777href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2778function allows you to check and change the behaviour, which is to not
2779substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2780
2781<p>Here is the DOM tree built by libxml for the previous document in the
2782default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2783<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2784DOCUMENT
2785version=1.0
2786 ELEMENT EXAMPLE
2787 TEXT
2788 content=
2789 ENTITY_REF
2790 INTERNAL_GENERAL_ENTITY xml
2791 content=Extensible Markup Language
2792 TEXT
2793 content=</pre>
2794
2795<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2796<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2797DOCUMENT
2798version=1.0
2799 ELEMENT EXAMPLE
2800 TEXT
2801 content= Extensible Markup Language</pre>
2802
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2803<p>So, entities or no entities? Basically, it depends on your use case. I
2804suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2805entities in your XML document or data if you are not willing to handle the
2806entity references elements in the DOM tree.</p>
2807
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2808<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2809entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2810transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2811reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2812finding them in the input).</p>
2813
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2814<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2815on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2816non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2817then 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]2818strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2819deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2820
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2821<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2822
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2823<p>The libxml library implements <a
2824href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2825recognizing namespace contructs in the input, and does namespace lookup
2826automatically when building the DOM tree. A namespace declaration is
2827associated with an in-memory structure and all elements or attributes within
2828that namespace point to it. Hence testing the namespace is a simple and fast
2829equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2830
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2831<p>I suggest that people using libxml use a namespace, and declare it in the
2832root element of their document as the default namespace. Then they don't need
2833to 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]2834refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2835the size of the XML output significantly, but significantly increases its
2836value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2837<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2838 &lt;elem1&gt;...&lt;/elem1&gt;
2839 &lt;elem2&gt;...&lt;/elem2&gt;
2840&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2841
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2842<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2843point to any existing resource on the Web. It will bind all the element and
2844atributes with that URL. I suggest to use an URL within a domain you control,
2845and that the URL should contain some kind of version information if possible.
2846For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2847namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2848
2849<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2850version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2851and if the version information don't match something you know, warn the user
2852and 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]2853namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2854same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2855associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2856just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2857<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2858prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2859
2860<p>@@Interfaces@@</p>
2861
2862<p>@@Examples@@</p>
2863
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2864<p>Usually people object to using namespaces together with validity checking.
2865I will try to make sure that using namespaces won't break validity checking,
2866so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2867suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2868<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2869flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2870from multiple DTDs will certainly break current validation schemes. I will
2871try to provide ways to do this, but this may not be portable or
2872standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2873
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2874<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2875
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2876<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2877
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2878<p>Version 2 of libxml is the first version introducing serious backward
2879incompatible changes. The main goals were:</p>
2880<ul>
2881 <li>a general cleanup. A number of mistakes inherited from the very early
2882 versions couldn't be changed due to compatibility constraints. Example
2883 the "childs" element in the nodes.</li>
2884 <li>Uniformization of the various nodes, at least for their header and link
2885 parts (doc, parent, children, prev, next), the goal is a simpler
2886 programming model and simplifying the task of the DOM implementors.</li>
2887 <li>better conformances to the XML specification, for example version 1.x
2888 had an heuristic to try to detect ignorable white spaces. As a result the
2889 SAX event generated were ignorableWhitespace() while the spec requires
2890 character() in that case. This also mean that a number of DOM node
2891 containing blank text may populate the DOM tree which were not present
2892 before.</li>
2893</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2894
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2895<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2896
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2897<p>So client code of libxml designed to run with version 1.x may have to be
2898changed to compile against version 2.x of libxml. Here is a list of changes
2899that I have collected, they may not be sufficient, so in case you find other
2900change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2901mail</a>:</p>
2902<ol>
2903 <li>The package name have changed from libxml to libxml2, the library name
2904 is now -lxml2 . There is a new xml2-config script which should be used to
2905 select the right parameters libxml2</li>
2906 <li>Node <strong>childs</strong> field has been renamed
2907 <strong>children</strong> so s/childs/children/g should be applied
2908 (probablility of having "childs" anywere else is close to 0+</li>
2909 <li>The document don't have anymore a <strong>root</strong> element it has
2910 been replaced by <strong>children</strong> and usually you will get a
2911 list of element here. For example a Dtd element for the internal subset
2912 and it's declaration may be found in that list, as well as processing
2913 instructions or comments found before or after the document root element.
2914 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2915 a document. Alternatively if you are sure to not reference Dtds nor have
2916 PIs or comments before or after the root element
2917 s/-&gt;root/-&gt;children/g will probably do it.</li>
2918 <li>The white space issue, this one is more complex, unless special case of
2919 validating parsing, the line breaks and spaces usually used for indenting
2920 and formatting the document content becomes significant. So they are
2921 reported by SAX and if your using the DOM tree, corresponding nodes are
2922 generated. Too approach can be taken:
2923 <ol>
2924 <li>lazy one, use the compatibility call
2925 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2926 relying on a special (and possibly broken) set of heuristics of
2927 libxml to detect ignorable blanks. Don't complain if it breaks or
2928 make your application not 100% clean w.r.t. to it's input.</li>
2929 <li>the Right Way: change you code to accept possibly unsignificant
2930 blanks characters, or have your tree populated with weird blank text
2931 nodes. You can spot them using the comodity function
2932 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2933 nodes.</li>
2934 </ol>
2935 <p>Note also that with the new default the output functions don't add any
2936 extra indentation when saving a tree in order to be able to round trip
2937 (read and save) without inflating the document with extra formatting
2938 chars.</p>
2939 </li>
2940 <li>The include path has changed to $prefix/libxml/ and the includes
2941 themselves uses this new prefix in includes instructions... If you are
2942 using (as expected) the
2943 <pre>xml2-config --cflags</pre>
2944 <p>output to generate you compile commands this will probably work out of
2945 the box</p>
2946 </li>
2947 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2948 byte of the head of the document available for character detection.</li>
2949</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2950
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2951<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2952
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2953<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
2954to allow smoth upgrade of existing libxml v1code while retaining
2955compatibility. They offers the following:</p>
2956<ol>
2957 <li>similar include naming, one should use
2958 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
2959 <li>similar identifiers defined via macros for the child and root fields:
2960 respectively <strong>xmlChildrenNode</strong> and
2961 <strong>xmlRootNode</strong></li>
2962 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
2963 inserted once in the client code</li>
2964</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2965
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2966<p>So the roadmap to upgrade your existing libxml applications is the
2967following:</p>
2968<ol>
2969 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
2970 <li>find all occurences where the xmlDoc <strong>root</strong> field is
2971 used and change it to <strong>xmlRootNode</strong></li>
2972 <li>similary find all occurences where the xmlNode <strong>childs</strong>
2973 field is used and change it to <strong>xmlChildrenNode</strong></li>
2974 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
2975 <strong>main()</strong> or in the library init entry point</li>
2976 <li>Recompile, check compatibility, it should still work</li>
2977 <li>Change your configure script to look first for xml2-config and fallback
2978 using xml-config . Use the --cflags and --libs ouptut of the command as
2979 the Include and Linking parameters needed to use libxml.</li>
2980 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
2981 libxml-devel-1.8.y can be kept simultaneously)</li>
2982 <li>remove your config.cache, relaunch your configuration mechanism, and
2983 recompile, if steps 2 and 3 were done right it should compile as-is</li>
2984 <li>Test that your application is still running correctly, if not this may
2985 be due to extra empty nodes due to formating spaces being kept in libxml2
2986 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
2987 code before calling the parser (next to
2988 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
2989</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2990
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2991<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]2992
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2993<p>Let me put some emphasis on the fact that there is far more changes from
2994libxml 1.x to 2.x than the ones you may have to patch for. The overall code
2995has been considerably cleaned up and the conformance to the XML specification
2996has been drastically improved too. Don't take those changes as an excuse to
2997not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2998
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]2999<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3000
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3001<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3002Object Model</em>; this is an API for accessing XML or HTML structured
3003documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3004and will be based on gnome-xml. This will be a far cleaner interface to
3005manipulate XML files within Gnome since it won't expose the internal
3006structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3007
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3008<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3009href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3010is a full DOM interface, thanks to Paolo Casarini, check the <a
3011href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3012informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3013
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3014<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3015
3016<p>Here is a real size example, where the actual content of the application
3017data 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]3018a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3019storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3020base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3021<pre>&lt;?xml version="1.0"?&gt;
3022&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3023 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3024
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3025 &lt;gjob:Job&gt;
3026 &lt;gjob:Project ID="3"/&gt;
3027 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3028 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3029
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3030 &lt;gjob:Update&gt;
3031 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3032 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3033 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3034 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3035
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3036 &lt;gjob:Developers&gt;
3037 &lt;gjob:Developer&gt;
3038 &lt;/gjob:Developer&gt;
3039 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3040
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3041 &lt;gjob:Contact&gt;
3042 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3043 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3044 &lt;gjob:Company&gt;
3045 &lt;/gjob:Company&gt;
3046 &lt;gjob:Organisation&gt;
3047 &lt;/gjob:Organisation&gt;
3048 &lt;gjob:Webpage&gt;
3049 &lt;/gjob:Webpage&gt;
3050 &lt;gjob:Snailmail&gt;
3051 &lt;/gjob:Snailmail&gt;
3052 &lt;gjob:Phone&gt;
3053 &lt;/gjob:Phone&gt;
3054 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3055
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3056 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3057 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3058 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3059
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3060 &lt;gjob:Skills&gt;
3061 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3062
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3063 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3064 A GNOME based system that will allow a superuser to configure
3065 compressed and uncompressed files and/or file systems to be backed
3066 up with a supported media in the system. This should be able to
3067 perform via find commands generating a list of files that are passed
3068 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3069 or via operations performed on the filesystem itself. Email
3070 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3071 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3072
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3073 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3074
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3075 &lt;/gjob:Jobs&gt;
3076&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3077
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3078<p>While loading the XML file into an internal DOM tree is a matter of
3079calling only a couple of functions, browsing the tree to gather the ata and
3080generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3081
3082<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3083structure. For example, the ordering of the attributes is not significant,
3084the 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]3085depend on the order of the children of a given node, unless it really makes
3086things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3087<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3088 * A person record
3089 */
3090typedef struct person {
3091 char *name;
3092 char *email;
3093 char *company;
3094 char *organisation;
3095 char *smail;
3096 char *webPage;
3097 char *phone;
3098} person, *personPtr;
3099
3100/*
3101 * And the code needed to parse it
3102 */
3103personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3104 personPtr ret = NULL;
3105
3106DEBUG("parsePerson\n");
3107 /*
3108 * allocate the struct
3109 */
3110 ret = (personPtr) malloc(sizeof(person));
3111 if (ret == NULL) {
3112 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3113 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3114 }
3115 memset(ret, 0, sizeof(person));
3116
3117 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3118 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3119 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3120 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3121 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3122 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3123 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3124 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3125 }
3126
3127 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3128}</pre>
3129
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3130<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3131<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3132 <li>Usually a recursive parsing style is the more convenient one: XML data
3133 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3134 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3135 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3136 i.e. the pointer to the global XML document and the namespace reserved to
3137 the application. Document wide information are needed for example to
3138 decode entities and it's a good coding practice to define a namespace for
3139 your application set of data and test that the element and attributes
3140 you're analyzing actually pertains to your application space. This is
3141 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3142 <li>To retrieve text and attributes value, you can use the function
3143 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3144 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3145</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3146
3147<p>Here is another piece of code used to parse another level of the
3148structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3149<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3150/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3151 * a Description for a Job
3152 */
3153typedef struct job {
3154 char *projectID;
3155 char *application;
3156 char *category;
3157 personPtr contact;
3158 int nbDevelopers;
3159 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3160} job, *jobPtr;
3161
3162/*
3163 * And the code needed to parse it
3164 */
3165jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3166 jobPtr ret = NULL;
3167
3168DEBUG("parseJob\n");
3169 /*
3170 * allocate the struct
3171 */
3172 ret = (jobPtr) malloc(sizeof(job));
3173 if (ret == NULL) {
3174 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3175 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3176 }
3177 memset(ret, 0, sizeof(job));
3178
3179 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3180 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3181 while (cur != NULL) {
3182
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3183 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3184 ret-&gt;projectID = xmlGetProp(cur, "ID");
3185 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3186 fprintf(stderr, "Project has no ID\n");
3187 }
3188 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3189 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3190 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3191 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3192 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3193 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3194 ret-&gt;contact = parsePerson(doc, ns, cur);
3195 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3196 }
3197
3198 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3199}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3200
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3201<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]3202boring. Ultimately, it could be possble to write stubbers taking either C
3203data structure definitions, a set of XML examples or an XML DTD and produce
3204the code needed to import and export the content between C data and XML
3205storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3206
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3207<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3208parsing example</a> as a template, it is also available with Makefile in the
3209Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3210
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3211<h2><a name="Contributi">Contributions</a></h2>
3212<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3213 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3214 patches, Gary Pennington worked on the validation API, threading support
3215 and Solaris port.</li>
3216 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame^]3217 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
3218 provides a C++ wrapper for libxml:<br>
3219 Website: <a
3220 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3221 Download: <a
3222 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3223 </li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3224 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3225 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3226 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3227 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3228 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3229 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3230 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3231 <li><a
3232 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3233 Sergeant</a>
3234 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3235 wrapper for libxml2/libxslt as part of the <a
3236 href="http://axkit.com/">AxKit XML application server</a></li>
3237 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3238 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3239 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3240 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3241 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3242 provided <a href="http://xmlsoft.org/messages/0488.html">man
3243 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3244 <li>there is a module for <a
3245 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3246 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3247 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3248 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3249 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3250</ul>
3251
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3252<p></p>
3253
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3254</body>
3255</html>