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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>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame^]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
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame^]432still open. Be sure to specify that the bug is for the package libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]433
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]434<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]435href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
436href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]437href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
438please visit the <a
439href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
440follow the instructions. <strong>Do not send code, I won't debug it</strong>
441(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]442
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]443<p>Check the following <strong><span style="color: #FF0000">before
444posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]445<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]446 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]447 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
448 version</a>, and that the problem still shows up in those</li>
449 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
450 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]451 there is probably a fix available, similary check the <a
452 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]453 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]454 <li>make sure you can reproduce the bug with xmllint or one of the test
455 programs found in source in the distribution</li>
456 <li>Please send the command showing the error as well as the input (as an
457 attachement)</li>
458</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]459
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]460<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]461href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]462related I will approve it.. Please do not send me mail directly, it makes
463things really harder to track and in some cases I'm not the best person to
464answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]465
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]466<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]467probably be processed faster.</p>
468
469<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]470href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]471provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]472questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]473documentantion</a> is not as polished as I would like (i need to learn more
474about Docbook), but it's a good starting point.</p>
475
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]476<h2><a name="help">How to help</a></h2>
477
478<p>You can help the project in various ways, the best thing to do first is to
479subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]480href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
481href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]482database:</a>:</p>
483<ol>
484 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]485 <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]486 be integrated in all cases but help pinpointing portability problems
487 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]488 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]489 as HTML diffs).</li>
490 <li>provide new documentations pieces (translations, examples, etc ...)</li>
491 <li>Check the TODO file and try to close one of the items</li>
492 <li>take one of the points raised in the archive or the bug database and
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]493 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
494 </a>before to avoid synchronization problems and check that the suggested
495 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]496</ol>
497
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]498<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]499
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]500<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]501href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
502href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
503href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]504href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]505as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]506archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]507href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
508packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]509href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
510href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]511packages installed to compile applications using libxml.) <a
512href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
513of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]514href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]515provides binaries</a>. <a href="mailto:Gary.Pennington@sun.com">Gary
516Pennington</a> provides <a
517href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris binaries</a>.</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]518
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]519<p><a name="Snapshot">Snapshot:</a></p>
520<ul>
521 <li>Code from the W3C cvs base libxml <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]522 href="ftp://xmlsoft.org/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]523 <li>Docs, content of the web site, the list archive included <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]524 href="ftp://xmlsoft.org/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]525</ul>
526
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]527<p><a name="Contribs">Contributions:</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]528
529<p>I do accept external contributions, especially if compiling on another
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]530platform, get in touch with me to upload the package, wrappers for various
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame^]531languages have been provided, and can be found in the <a
532href="contribs.html">contrib section</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]533
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]534<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]535<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]536 <li><p>The <a
537 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Gnome
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]538 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]539 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
540 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]541 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]542 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]543</ul>
544
545<h2><a name="News">News</a></h2>
546
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]547<h3>CVS only : check the <a
548href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]549for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]550
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]551<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]552you want to test those</p>
553<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]554 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
555 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]556 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
557 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]558 <li>(seeems working but delayed from release) parsing/import of Docbook
559 SGML docs</li>
560</ul>
561
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]562<h3>2.4.6: Oct 10 2001</h3>
563<ul>
564 <li>added and updated man pages by John Fleck</li>
565 <li>portability and configure fixes</li>
566 <li>an infinite loop on the HTML parser was removed (William)</li>
567 <li>Windows makefile patches from Igor</li>
568 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
569 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
570</ul>
571
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]572<h3>2.4.5: Sep 14 2001</h3>
573<ul>
574 <li>Remove a few annoying bugs in 2.4.4</li>
575 <li>forces the HTML serializer to output decimal charrefs since some
576 version of Netscape can't handle hexadecimal ones</li>
577</ul>
578
579<h3>1.8.16: Sep 14 2001</h3>
580<ul>
581 <li>maintenance release of the old libxml1 branch, couple of bug and
582 portability fixes</li>
583</ul>
584
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]585<h3>2.4.4: Sep 12 2001</h3>
586<ul>
587 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
588 Catalog</li>
589 <li>a few bug fixes and some portability changes</li>
590 <li>some documentation cleanups</li>
591</ul>
592
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]593<h3>2.4.3: Aug 23 2001</h3>
594<ul>
595 <li>XML Catalog support see the doc</li>
596 <li>New NaN/Infinity floating point code</li>
597 <li>A few bug fixes</li>
598</ul>
599
600<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]601<ul>
602 <li>adds xmlLineNumbersDefault() to control line number generation</li>
603 <li>lot of bug fixes</li>
604 <li>the Microsoft MSC projects files shuld now be up to date</li>
605 <li>inheritance of namespaces from DTD defaulted attributes</li>
606 <li>fixes a serious potential security bug</li>
607 <li>added a --format option to xmllint</li>
608</ul>
609
610<h3>2.4.1: July 24 2001</h3>
611<ul>
612 <li>possibility to keep line numbers in the tree</li>
613 <li>some computation NaN fixes</li>
614 <li>extension of the XPath API</li>
615 <li>cleanup for alpha and ia64 targets</li>
616 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]617</ul>
618
619<h3>2.4.0: July 10 2001</h3>
620<ul>
621 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
622 <li>Fixed XML Base implementation, added a coupel of examples to the
623 regression tests</li>
624 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]625</ul>
626
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]627<h3>2.3.14: July 5 2001</h3>
628<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]629 <li>fixed some entities problems and reduce mem requirement when
630 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]631 <li>lots of improvements in the XPath queries interpreter can be
632 substancially faster</li>
633 <li>Makefiles and configure cleanups</li>
634 <li>Fixes to XPath variable eval, and compare on empty node set</li>
635 <li>HTML tag closing bug fixed</li>
636 <li>Fixed an URI reference computating problem when validating</li>
637</ul>
638
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]639<h3>2.3.13: June 28 2001</h3>
640<ul>
641 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
642 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
643</ul>
644
645<h3>1.8.14: June 28 2001</h3>
646<ul>
647 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
648 <li>Small Makefile fix</li>
649</ul>
650
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]651<h3>2.3.12: June 26 2001</h3>
652<ul>
653 <li>lots of cleanup</li>
654 <li>a couple of validation fix</li>
655 <li>fixed line number counting</li>
656 <li>fixed serious problems in the XInclude processing</li>
657 <li>added support for UTF8 BOM at beginning of entities</li>
658 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
659 miscompile uri.c (William), Thomas Leitner provided a fix for the
660 optimizer on Tru64</li>
661 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
662 compilation on Windows MSC</li>
663 <li>update of libxml-doc.el (Felix Natter)</li>
664 <li>fixed 2 bugs in URI normalization code</li>
665</ul>
666
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]667<h3>2.3.11: June 17 2001</h3>
668<ul>
669 <li>updates to trio, Makefiles and configure should fix some portability
670 problems (alpha)</li>
671 <li>fixed some HTML serialization problems (pre, script, and block/inline
672 handling), added encoding aware APIs, cleanup of this code</li>
673 <li>added xmlHasNsProp()</li>
674 <li>implemented a specific PI for encoding support in the DocBook SGML
675 parser</li>
676 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
677 node selection)</li>
678 <li>fixed a performance problem and an error in the validation code</li>
679 <li>fixed XInclude routine to implement the recursive behaviour</li>
680 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
681 <li>added --version to xmllint for bug reports</li>
682</ul>
683
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]684<h3>2.3.10: June 1 2001</h3>
685<ul>
686 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]687 <li>a number of reported bugs got fixed, in XPath, iconv detection,
688 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]689 <li>XPath string function should now handle unicode correctly</li>
690</ul>
691
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]692<h3>2.3.9: May 19 2001</h3>
693
694<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
695<ul>
696 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
697 <li>some serious speed optimisation again</li>
698 <li>some documentation cleanups</li>
699 <li>trying to get better linking on solaris (-R)</li>
700 <li>XPath API cleanup from Thomas Broyer</li>
701 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
702 xmlValidGetValidElements()</li>
703 <li>Added an INSTALL file</li>
704 <li>Attribute removal added to API: #54433</li>
705 <li>added a basic support for SGML catalogs</li>
706 <li>fixed xmlKeepBlanksDefault(0) API</li>
707 <li>bugfix in xmlNodeGetLang()</li>
708 <li>fixed a small configure portability problem</li>
709 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
710</ul>
711
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]712<h3>1.8.13: May 14 2001</h3>
713<ul>
714 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
715</ul>
716
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]717<h3>2.3.8: May 3 2001</h3>
718<ul>
719 <li>Integrated an SGML DocBook parser for the Gnome project</li>
720 <li>Fixed a few things in the HTML parser</li>
721 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
722 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]723 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
724 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]725 <li>incorporated more Windows cleanup</li>
726 <li>added xmlSaveFormatFile()</li>
727 <li>fixed problems in copying nodes with entities references (gdome)</li>
728 <li>removed some troubles surrounding the new validation module</li>
729</ul>
730
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]731<h3>2.3.7: April 22 2001</h3>
732<ul>
733 <li>lots of small bug fixes, corrected XPointer</li>
734 <li>Non determinist content model validation support</li>
735 <li>added xmlDocCopyNode for gdome2</li>
736 <li>revamped the way the HTML parser handles end of tags</li>
737 <li>XPath: corrctions of namespacessupport and number formatting</li>
738 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
739 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
740 <li>Improved validation speed sensible for DocBook</li>
741 <li>fixed a big bug with ID declared in external parsed entities</li>
742 <li>portability fixes, update of Trio from Bjorn Reese</li>
743</ul>
744
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]745<h3>2.3.6: April 8 2001</h3>
746<ul>
747 <li>Code cleanup using extreme gcc compiler warning options, found and
748 cleared half a dozen potential problem</li>
749 <li>the Eazel team found an XML parser bug</li>
750 <li>cleaned up the user of some of the string formatting function. used the
751 trio library code to provide the one needed when the platform is missing
752 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]753 <li>xpath: removed a memory leak and fixed the predicate evaluation
754 problem, extended the testsuite and cleaned up the result. XPointer seems
755 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]756</ul>
757
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]758<h3>2.3.5: Mar 23 2001</h3>
759<ul>
760 <li>Biggest change is separate parsing and evaluation of XPath expressions,
761 there is some new APIs for this too</li>
762 <li>included a number of bug fixes(XML push parser, 51876, notations,
763 52299)</li>
764 <li>Fixed some portability issues</li>
765</ul>
766
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]767<h3>2.3.4: Mar 10 2001</h3>
768<ul>
769 <li>Fixed bugs #51860 and #51861</li>
770 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
771 size to be application tunable.</li>
772 <li>Some cleanup in the validation code, still a bug left and this part
773 should probably be rewritten to support ambiguous content model :-\</li>
774 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
775 parser</li>
776 <li>Fixed another bug in xmlNodeGetContent()</li>
777 <li>Bjorn fixed XPath node collection and Number formatting</li>
778 <li>Fixed a loop reported in the HTML parsing</li>
779 <li>blank space are reported even if the Dtd content model proves that they
780 are formatting spaces, this is for XmL conformance</li>
781</ul>
782
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]783<h3>2.3.3: Mar 1 2001</h3>
784<ul>
785 <li>small change in XPath for XSLT</li>
786 <li>documentation cleanups</li>
787 <li>fix in validation by Gary Pennington</li>
788 <li>serious parsing performances improvements</li>
789</ul>
790
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]791<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]792<ul>
793 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
794 <li>fixed a Dtd parsing bug</li>
795 <li>fixed a bug in xmlNodeGetContent</li>
796 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
797</ul>
798
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]799<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]800<ul>
801 <li>some XPath and HTML bug fixes for XSLT</li>
802 <li>small extension of the hash table interfaces for DOM gdome2
803 implementation</li>
804 <li>A few bug fixes</li>
805</ul>
806
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]807<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]808<ul>
809 <li>Lots of XPath bug fixes</li>
810 <li>Add a mode with Dtd lookup but without validation error reporting for
811 XSLT</li>
812 <li>Add support for text node without escaping (XSLT)</li>
813 <li>bug fixes for xmlCheckFilename</li>
814 <li>validation code bug fixes from Gary Pennington</li>
815 <li>Patch from Paul D. Smith correcting URI path normalization</li>
816 <li>Patch to allow simultaneous install of libxml-devel and
817 libxml2-devel</li>
818 <li>the example Makefile is now fixed</li>
819 <li>added HTML to the RPM packages</li>
820 <li>tree copying bugfixes</li>
821 <li>updates to Windows makefiles</li>
822 <li>optimisation patch from Bjorn Reese</li>
823</ul>
824
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]825<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]826<ul>
827 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
828 <li>added htmlHandleOmittedElem()</li>
829 <li>Applied Bjorn Reese's IPV6 first patch</li>
830 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]831 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]832</ul>
833
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]834<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]835<ul>
836 <li>Fix the Windows problems of 2.2.8</li>
837 <li>integrate OpenVMS patches</li>
838 <li>better handling of some nasty HTML input</li>
839 <li>Improved the XPointer implementation</li>
840 <li>integrate a number of provided patches</li>
841</ul>
842
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]843<h3>2.2.9: Nov 25 2000</h3>
844<ul>
845 <li>erroneous release :-(</li>
846</ul>
847
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]848<h3>2.2.8: Nov 13 2000</h3>
849<ul>
850 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
851 support</li>
852 <li>Patch in conditional section handling</li>
853 <li>updated MS compiler project</li>
854 <li>fixed some XPath problems</li>
855 <li>added an URI escaping function</li>
856 <li>some other bug fixes</li>
857</ul>
858
859<h3>2.2.7: Oct 31 2000</h3>
860<ul>
861 <li>added message redirection</li>
862 <li>XPath improvements (thanks TOM !)</li>
863 <li>xmlIOParseDTD() added</li>
864 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
865 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
866</ul>
867
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]868<h3>2.2.6: Oct 25 2000:</h3>
869<ul>
870 <li>Added an hash table module, migrated a number of internal structure to
871 those</li>
872 <li>Fixed a posteriori validation problems</li>
873 <li>HTTP module cleanups</li>
874 <li>HTML parser improvements (tag errors, script/style handling, attribute
875 normalization)</li>
876 <li>coalescing of adjacent text nodes</li>
877 <li>couple of XPath bug fixes, exported the internal API</li>
878</ul>
879
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]880<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]881<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]882 <li>XPointer implementation and testsuite</li>
883 <li>Lot of XPath fixes, added variable and functions registration, more
884 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]885 <li>Portability fixes, lots of enhancements toward an easy Windows build
886 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]887 <li>Late validation fixes</li>
888 <li>Integrated a lot of contributed patches</li>
889 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]890 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]891</ul>
892
893<h3>2.2.4: Oct 1 2000:</h3>
894<ul>
895 <li>main XPath problem fixed</li>
896 <li>Integrated portability patches for Windows</li>
897 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]898</ul>
899
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]900<h3>2.2.3: Sep 17 2000</h3>
901<ul>
902 <li>bug fixes</li>
903 <li>cleanup of entity handling code</li>
904 <li>overall review of all loops in the parsers, all sprintf usage has been
905 checked too</li>
906 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
907 works smoothly now.</li>
908</ul>
909
910<h3>1.8.10: Sep 6 2000</h3>
911<ul>
912 <li>bug fix release for some Gnome projects</li>
913</ul>
914
915<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]916<ul>
917 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]918 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]919</ul>
920
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]921<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]922<ul>
923 <li>a purely bug fixes release</li>
924 <li>fixed an encoding support problem when parsing from a memory block</li>
925 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]926 <li>removed a bug in the function allowing to override the memory
927 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]928</ul>
929
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]930<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]931<ul>
932 <li>applied a lot of portability fixes</li>
933 <li>better encoding support/cleanup and saving (content is now always
934 encoded in UTF-8)</li>
935 <li>the HTML parser now correctly handles encodings</li>
936 <li>added xmlHasProp()</li>
937 <li>fixed a serious problem with &amp;#38;</li>
938 <li>propagated the fix to FTP client</li>
939 <li>cleanup, bugfixes, etc ...</li>
940 <li>Added a page about <a href="encoding.html">libxml Internationalization
941 support</a></li>
942</ul>
943
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]944<h3>1.8.9: July 9 2000</h3>
945<ul>
946 <li>fixed the spec the RPMs should be better</li>
947 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
948 rpmfind users problem</li>
949</ul>
950
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]951<h3>2.1.1: July 1 2000</h3>
952<ul>
953 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
954 <li>improvements on the HTML parser</li>
955</ul>
956
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]957<h3>2.1.0 and 1.8.8: June 29 2000</h3>
958<ul>
959 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
960 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
961 about &amp;#38; charref parsing</li>
962 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
963 also contains numerous fixes and enhancements:
964 <ul>
965 <li>added xmlStopParser() to stop parsing</li>
966 <li>improved a lot parsing speed when there is large CDATA blocs</li>
967 <li>includes XPath patches provided by Picdar Technology</li>
968 <li>tried to fix as much as possible DtD validation and namespace
969 related problems</li>
970 <li>output to a given encoding has been added/tested</li>
971 <li>lot of various fixes</li>
972 </ul>
973 </li>
974</ul>
975
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]976<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]977<ul>
978 <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]979 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
980 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
981 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]982 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]983 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]984 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]985 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]986 <pre>#include "xxx.h"</pre>
987 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]988 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
989 <li>the memory allocation routines used by libxml can now be overloaded
990 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]991 <li>The previously CVS only tool tester has been renamed
992 <strong>xmllint</strong> and is now installed as part of the libxml2
993 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]994 <li>The I/O interface has been revamped. There is now ways to plug in
995 specific I/O modules, either at the URI scheme detection level using
996 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
997 parser context using xmlCreateIOParserCtxt()</li>
998 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
999 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1000 <li>a number of optional features of libxml can now be excluded at
1001 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1002</ul>
1003
1004<h3>2.0.0beta: Mar 14 2000</h3>
1005<ul>
1006 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1007 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1008 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1009 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1010 <li>This version is now the head in the Gnome CVS base, the old one is
1011 available under the tag LIB_XML_1_X</li>
1012 <li>This includes a very large set of changes. Froma programmatic point of
1013 view applications should not have to be modified too much, check the <a
1014 href="upgrade.html">upgrade page</a></li>
1015 <li>Some interfaces may changes (especially a bit about encoding).</li>
1016 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1017 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1018 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1019 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1020 <li>Better handling of entities, especially well formedness checking
1021 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1022 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1023 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1024 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1025 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1026 </ul>
1027 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1028 <li>Serious progress were made toward compliance, <a
1029 href="conf/result.html">here are the result of the test</a> against the
1030 OASIS testsuite (except the japanese tests since I don't support that
1031 encoding yet). This URL is rebuilt every couple of hours using the CVS
1032 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1033</ul>
1034
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1035<h3>1.8.7: Mar 6 2000</h3>
1036<ul>
1037 <li>This is a bug fix release:</li>
1038 <li>It is possible to disable the ignorable blanks heuristic used by
1039 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1040 that for adherence to XML spec, this behaviour will be disabled by
1041 default in 2.x . The same function will allow to keep compatibility for
1042 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1043 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1044 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1045 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1046 compilation on some platforms has been fixed</li>
1047 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1048 URIs</li>
1049</ul>
1050
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1051<h3>1.8.6: Jan 31 2000</h3>
1052<ul>
1053 <li>added a nanoFTP transport module, debugged until the new version of <a
1054 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1055 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1056</ul>
1057
1058<h3>1.8.5: Jan 21 2000</h3>
1059<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1060 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1061 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1062 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1063 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1064 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1065 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1066 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1067 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1068</ul>
1069
1070<h3>1.8.4: Jan 13 2000</h3>
1071<ul>
1072 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1073 <li>all exit() call should have been removed from libxml</li>
1074 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1075 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1076</ul>
1077
1078<h3>1.8.3: Jan 5 2000</h3>
1079<ul>
1080 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1081 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1082 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1083 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1084 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1085 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1086 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1087 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1088 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1089</ul>
1090
1091<h3>1.8.2: Dec 21 1999</h3>
1092<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1093 <li>I got another problem with includes and C++, I hope this issue is fixed
1094 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1095 <li>Added a few tree modification functions: xmlReplaceNode,
1096 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1097 xmlDocSetRootElement</li>
1098 <li>Tried to improve the HTML output with help from <a
1099 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1100</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1101
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1102<h3>1.8.1: Dec 18 1999</h3>
1103<ul>
1104 <li>various patches to avoid troubles when using libxml with C++ compilers
1105 the "namespace" keyword and C escaping in include files</li>
1106 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1107 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1108 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1109 <li>fixed a posteriori validation (validation after parsing, or by using a
1110 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1111 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1112</ul>
1113
1114<h3>1.8.0: Dec 12 1999</h3>
1115<ul>
1116 <li>cleanup, especially memory wise</li>
1117 <li>the parser should be more reliable, especially the HTML one, it should
1118 not crash, whatever the input !</li>
1119 <li>Integrated various patches, especially a speedup improvement for large
1120 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1121 configure with --with-buffers to enable them.</li>
1122 <li>attribute normalization, oops should have been added long ago !</li>
1123 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1124 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1125</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1126
1127<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1128<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1129 <li>Lots of HTML improvement</li>
1130 <li>Fixed some errors when saving both XML and HTML</li>
1131 <li>More examples, the regression tests should now look clean</li>
1132 <li>Fixed a bug with contiguous charref</li>
1133</ul>
1134
1135<h3>1.7.3: Sep 29 1999</h3>
1136<ul>
1137 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1138 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1139 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1140</ul>
1141
1142<h3>1.7.1: Sep 24 1999</h3>
1143<ul>
1144 <li>The basic type for strings manipulated by libxml has been renamed in
1145 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1146 is that CHAR was conflicting with a predefined type on Windows. However
1147 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1148 <strong>#define </strong>.</li>
1149 <li>Changed another error : the use of a structure field called errno, and
1150 leading to troubles on platforms where it's a macro</li>
1151</ul>
1152
1153<h3>1.7.0: sep 23 1999</h3>
1154<ul>
1155 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1156 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1157 <li>Added an errno to report errors by another mean than a simple printf
1158 like callback</li>
1159 <li>Finished ID/IDREF support and checking when validation</li>
1160 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1161 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1162 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1163 implementation</li>
1164 <li>Added an HTML parser front-end</li>
1165</ul>
1166
1167<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1168
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1169<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]1170markup-based structured documents. Here is <a name="example">an example XML
1171document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1172<pre>&lt;?xml version="1.0"?&gt;
1173&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1174 &lt;head&gt;
1175 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1176 &lt;/head&gt;
1177 &lt;chapter&gt;
1178 &lt;title&gt;The Linux adventure&lt;/title&gt;
1179 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1180 &lt;image href="linus.gif"/&gt;
1181 &lt;p&gt;...&lt;/p&gt;
1182 &lt;/chapter&gt;
1183&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1184
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1185<p>The first line specifies that it's an XML document and gives useful
1186information about its encoding. Then the document is a text format whose
1187structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1188to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1189(no content), a single tag can serve as both the opening and closing tag if
1190it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1191that, for example, the image tag has no content (just an attribute) and is
1192closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1193
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1194<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]1195structured document maintenance (where it follows the steps of SGML) to
1196simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1197spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1198it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1199
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1200<h2><a name="XSLT">XSLT</a></h2>
1201
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1202<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1203
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1204<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1205language for transforming XML documents into other XML documents (or
1206HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1207
1208<p>A separate library called libxslt is being built on top of libxml2. This
1209module "libxslt" can be found in the Gnome CVS base too.</p>
1210
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1211<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1212href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1213supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1214href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1215
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1216<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1217
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1218<p>Libxml is made of multiple components; some of them are optional, and most
1219of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1220<ul>
1221 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1222 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1223 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1224 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1225 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1226 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1227 <li>a SAX tree module to build an in-memory DOM representation</li>
1228 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1229 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1230 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1231 (optional)</li>
1232 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1233</ul>
1234
1235<p>Graphically this gives the following:</p>
1236
1237<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1238
1239<p></p>
1240
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1241<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1242
1243<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1244returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1245<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1246as the file name, the document type, and a <strong>children</strong> pointer
1247which is the root of the document (or more exactly the first child under the
1248root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1249chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1250relationship. An xmlNode can also carry properties (a chain of xmlAttr
1251structures). An attribute may have a value which is a list of TEXT or
1252ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1253
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1254<p>Here is an example (erroneous with respect to the XML spec since there
1255should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1256
1257<p><img src="structure.gif" alt=" structure.gif "></p>
1258
1259<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1260called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1261prints them back as parsed. This is useful for detecting errors both in XML
1262code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1263which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1264result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1265<pre>DOCUMENT
1266version=1.0
1267standalone=true
1268 ELEMENT EXAMPLE
1269 ATTRIBUTE prop1
1270 TEXT
1271 content=gnome is great
1272 ATTRIBUTE prop2
1273 ENTITY_REF
1274 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1275 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1276 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1277 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1278 TEXT
1279 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1280 ELEMENT chapter
1281 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1282 TEXT
1283 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1284 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1285 TEXT
1286 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1287 ELEMENT image
1288 ATTRIBUTE href
1289 TEXT
1290 content=linus.gif
1291 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1292 TEXT
1293 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1294
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1295<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1296
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1297<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1298
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1299<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1300memory. 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]1301loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1302a <strong>callback-based interface</strong> to the parser. Before parsing,
1303the application layer registers a customized set of callbacks which are
1304called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1305
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1306<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]1307libxml, see the <a
1308href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1309documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1310Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1311
1312<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1313program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1314binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1315distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1316testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1317<pre>SAX.setDocumentLocator()
1318SAX.startDocument()
1319SAX.getEntity(amp)
1320SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1321SAX.characters( , 3)
1322SAX.startElement(head)
1323SAX.characters( , 4)
1324SAX.startElement(title)
1325SAX.characters(Welcome to Gnome, 16)
1326SAX.endElement(title)
1327SAX.characters( , 3)
1328SAX.endElement(head)
1329SAX.characters( , 3)
1330SAX.startElement(chapter)
1331SAX.characters( , 4)
1332SAX.startElement(title)
1333SAX.characters(The Linux adventure, 19)
1334SAX.endElement(title)
1335SAX.characters( , 4)
1336SAX.startElement(p)
1337SAX.characters(bla bla bla ..., 15)
1338SAX.endElement(p)
1339SAX.characters( , 4)
1340SAX.startElement(image, href='linus.gif')
1341SAX.endElement(image)
1342SAX.characters( , 4)
1343SAX.startElement(p)
1344SAX.characters(..., 3)
1345SAX.endElement(p)
1346SAX.characters( , 3)
1347SAX.endElement(chapter)
1348SAX.characters( , 1)
1349SAX.endElement(EXAMPLE)
1350SAX.endDocument()</pre>
1351
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1352<p>Most of the other interfaces of libxml are based on the DOM tree-building
1353facility, so nearly everything up to the end of this document presupposes the
1354use of the standard DOM tree build. Note that the DOM tree itself is built by
1355a set of registered default callbacks, without internal specific
1356interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1357
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1358<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1359
1360<p>Table of Content:</p>
1361<ol>
1362 <li><a href="#General5">General overview</a></li>
1363 <li><a href="#definition">The definition</a></li>
1364 <li><a href="#Simple">Simple rules</a>
1365 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1366 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1367 <li><a href="#Declaring">Declaring elements</a></li>
1368 <li><a href="#Declaring1">Declaring attributes</a></li>
1369 </ol>
1370 </li>
1371 <li><a href="#Some">Some examples</a></li>
1372 <li><a href="#validate">How to validate</a></li>
1373 <li><a href="#Other">Other resources</a></li>
1374</ol>
1375
1376<h3><a name="General5">General overview</a></h3>
1377
1378<p>Well what is validation and what is a DTD ?</p>
1379
1380<p>DTD is the acronym for Document Type Definition. This is a description of
1381the content for a familly of XML files. This is part of the XML 1.0
1382specification, and alows to describe and check that a given document instance
1383conforms to a set of rules detailing its structure and content.</p>
1384
1385<p>Validation is the process of checking a document against a DTD (more
1386generally against a set of construction rules).</p>
1387
1388<p>The validation process and building DTDs are the two most difficult parts
1389of the XML life cycle. Briefly a DTD defines all the possibles element to be
1390found within your document, what is the formal shape of your document tree
1391(by defining the allowed content of an element, either text, a regular
1392expression for the allowed list of children, or mixed content i.e. both text
1393and children). The DTD also defines the allowed attributes for all elements
1394and the types of the attributes.</p>
1395
1396<h3><a name="definition1">The definition</a></h3>
1397
1398<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1399href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1400Rev1</a>):</p>
1401<ul>
1402 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1403 elements</a></li>
1404 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1405 attributes</a></li>
1406</ul>
1407
1408<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1409ancient...</p>
1410
1411<h3><a name="Simple1">Simple rules</a></h3>
1412
1413<p>Writing DTD can be done in multiple ways, the rules to build them if you
1414need something fixed or something which can evolve over time can be radically
1415different. Really complex DTD like Docbook ones are flexible but quite harder
1416to design. I will just focuse on DTDs for a formats with a fixed simple
1417structure. It is just a set of basic rules, and definitely not exhaustive nor
1418useable for complex DTD design.</p>
1419
1420<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1421
1422<p>Assuming the top element of the document is <code>spec</code> and the dtd
1423is placed in the file <code>mydtd</code> in the subdirectory
1424<code>dtds</code> of the directory from where the document were loaded:</p>
1425
1426<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1427
1428<p>Notes:</p>
1429<ul>
1430 <li>the system string is actually an URI-Reference (as defined in <a
1431 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1432 full URL string indicating the location of your DTD on the Web, this is a
1433 really good thing to do if you want others to validate your document</li>
1434 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1435 magic string) so that the DTd is looked up in catalogs on the client side
1436 without having to locate it on the web</li>
1437 <li>a dtd contains a set of elements and attributes declarations, but they
1438 don't define what the root of the document should be. This is explicitely
1439 told to the parser/validator as the first element of the
1440 <code>DOCTYPE</code> declaration.</li>
1441</ul>
1442
1443<h4><a name="Declaring2">Declaring elements</a>:</h4>
1444
1445<p>The following declares an element <code>spec</code>:</p>
1446
1447<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1448
1449<p>it also expresses that the spec element contains one <code>front</code>,
1450one <code>body</code> and one optionnal <code>back</code> children elements
1451in this order. The declaration of one element of the structure and its
1452content are done in a single declaration. Similary the following declares
1453<code>div1</code> elements:</p>
1454
1455<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1456
1457<p>means div1 contains one <code>head</code> then a series of optional
1458<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1459optional <code>div2</code>. And last but not least an element can contain
1460text:</p>
1461
1462<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1463
1464<p><code>b</code> contains text or being of mixed content (text and elements
1465in no particular order):</p>
1466
1467<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1468
1469<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1470<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1471order.</p>
1472
1473<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1474
1475<p>again the attributes declaration includes their content definition:</p>
1476
1477<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1478
1479<p>means that the element <code>termdef</code> can have a <code>name</code>
1480attribute containing text (<code>CDATA</code>) and which is optionnal
1481(<code>#IMPLIED</code>). The attribute value can also be defined within a
1482set:</p>
1483
1484<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1485"ordered"&gt;</code></p>
1486
1487<p>means <code>list</code> element have a <code>type</code> attribute with 3
1488allowed values "bullets", "ordered" or "glossary" and which default to
1489"ordered" if the attribute is not explicitely specified.</p>
1490
1491<p>The content type of an attribute can be text (<code>CDATA</code>),
1492anchor/reference/references
1493(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1494(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1495(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1496<code>chapter</code> element can have an optional <code>id</code> attribute
1497of type <code>ID</code>, usable for reference from attribute of type
1498IDREF:</p>
1499
1500<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1501
1502<p>The last value of an attribute definition can be <code>#REQUIRED
1503</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1504meaning that it is optional, or the default value (possibly prefixed by
1505<code>#FIXED</code> if it is the only allowed).</p>
1506
1507<p>Notes:</p>
1508<ul>
1509 <li>usually the attributes pertaining to a given element are declared in a
1510 single expression, but it is just a convention adopted by a lot of DTD
1511 writers:
1512 <pre>&lt;!ATTLIST termdef
1513 id ID #REQUIRED
1514 name CDATA #IMPLIED&gt;</pre>
1515 <p>The previous construct defines both <code>id</code> and
1516 <code>name</code> attributes for the element <code>termdef</code></p>
1517 </li>
1518</ul>
1519
1520<h3><a name="Some1">Some examples</a></h3>
1521
1522<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1523contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1524example shows an XML file where the simple DTD is directly included within
1525the document.</p>
1526
1527<h3><a name="validate1">How to validate</a></h3>
1528
1529<p>The simplest is to use the xmllint program comming with libxml. The
1530<code>--valid</code> option turn on validation of the files given as input,
1531for example the following validates a copy of the first revision of the XML
15321.0 specification:</p>
1533
1534<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1535
1536<p>the -- noout is used to not output the resulting tree.</p>
1537
1538<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1539a given DTD.</p>
1540
1541<p>Libxml exports an API to handle DTDs and validation, check the <a
1542href="http://xmlsoft.org/html/libxml-valid.html">associated
1543description</a>.</p>
1544
1545<h3><a name="Other1">Other resources</a></h3>
1546
1547<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1548will just list one for now, others pointers welcome:</p>
1549<ul>
1550 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1551</ul>
1552
1553<p>I suggest looking at the examples found under test/valid/dtd and any of
1554the large number of books available on XML. The dia example in test/valid
1555should be both simple and complete enough to allow you to build your own.</p>
1556
1557<p></p>
1558
1559<h2><a name="Memory">Memory Management</a></h2>
1560
1561<p>Table of Content:</p>
1562<ol>
1563 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1564 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1565 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1566 <li><a href="#Debugging">Debugging routines</a></li>
1567 <li><a href="#General4">General memory requirements</a></li>
1568</ol>
1569
1570<h3><a name="General3">General overview</a></h3>
1571
1572<p>The module <code><a
1573href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1574provides the interfaces to the libxml memory system:</p>
1575<ul>
1576 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1577 xmlMalloc() and xmlRealloc()</li>
1578 <li>those routines can be reallocated to a specific set of routine, by
1579 default the libc ones i.e. free(), malloc() and realloc()</li>
1580 <li>the xmlmemory.c module includes a set of debugging routine</li>
1581</ul>
1582
1583<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1584
1585<p>It is sometimes useful to not use the default memory allocator, either for
1586debugging, analysis or to implement a specific behaviour on memory management
1587(like on embedded systems). Two function calls are available to do so:</p>
1588<ul>
1589 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1590 which return the current set of functions in use by the parser</li>
1591 <li><a
1592 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1593 which allow to set up a new set of memory allocation functions</li>
1594</ul>
1595
1596<p>Of course a call to xmlMemSetup() should probably be done before calling
1597any other libxml routines (unless you are sure your allocations routines are
1598compatibles).</p>
1599
1600<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1601
1602<p>Libxml is not stateless, there is a few set of memory structures needing
1603allocation before the parser is fully functionnal (some encoding structures
1604for example). This also mean that once parsing is finished there is a tiny
1605amount of memory (a few hundred bytes) which can be recollected if you don't
1606reuse the parser immediately:</p>
1607<ul>
1608 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1609 ()</a>
1610 is a centralized routine to free the parsing states. Note that it won't
1611 deallocate any produced tree if any (use the xmlFreeDoc() and related
1612 routines for this).</li>
1613 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1614 ()</a>
1615 is the dual routine allowing to preallocate the parsing state which can
1616 be useful for example to avoid initialization reentrancy problems when
1617 using libxml in multithreaded applications</li>
1618</ul>
1619
1620<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1621at the next invocation of parser routines, but be careful of the consequences
1622in multithreaded applications.</p>
1623
1624<h3><a name="Debugging">Debugging routines</a></h3>
1625
1626<p>When configured using --with-mem-debug flag (off by default), libxml uses
1627a set of memory allocation debugging routineskeeping track of all allocated
1628blocks and the location in the code where the routine was called. A couple of
1629other debugging routines allow to dump the memory allocated infos to a file
1630or call a specific routine when a given block number is allocated:</p>
1631<ul>
1632 <li><a
1633 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1634 <a
1635 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1636 and <a
1637 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1638 are the memory debugging replacement allocation routines</li>
1639 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1640 ()</a>
1641 dumps all the informations about the allocated memory block lefts in the
1642 <code>.memdump</code> file</li>
1643</ul>
1644
1645<p>When developping libxml memory debug is enabled, the tests programs call
1646xmlMemoryDump () and the "make test" regression tests will check for any
1647memory leak during the full regression test sequence, this helps a lot
1648ensuring that libxml does not leak memory and bullet proof memory
1649allocations use (some libc implementations are known to be far too permissive
1650resulting in major portability problems!).</p>
1651
1652<p>If the .memdump reports a leak, it displays the allocation function and
1653also tries to give some informations about the content and structure of the
1654allocated blocks left. This is sufficient in most cases to find the culprit,
1655but not always. Assuming the allocation problem is reproductible, it is
1656possible to find more easilly:</p>
1657<ol>
1658 <li>write down the block number xxxx not allocated</li>
1659 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1660 <li>run the program under a debugger and set a breakpoint on
1661 xmlMallocBreakpoint() a specific function called when this precise block
1662 is allocated</li>
1663 <li>when the breakpoint is reached you can then do a fine analysis of the
1664 allocation an step to see the condition resulting in the missing
1665 deallocation.</li>
1666</ol>
1667
1668<p>I used to use a commercial tool to debug libxml memory problems but after
1669noticing that it was not detecting memory leaks that simple mechanism was
1670used and proved extremely efficient until now.</p>
1671
1672<h3><a name="General4">General memory requirements</a></h3>
1673
1674<p>How much libxml memory require ? It's hard to tell in average it depends
1675of a number of things:</p>
1676<ul>
1677 <li>the parser itself should work in a fixed amout of memory, except for
1678 information maintained about the stacks of names and entities locations.
1679 The I/O and encoding handlers will probably account for a few KBytes.
1680 This is true for both the XML and HTML parser (though the HTML parser
1681 need more state).</li>
1682 <li>If you are generating the DOM tree then memory requirements will grow
1683 nearly lineary with the size of the data. In general for a balanced
1684 textual document the internal memory requirement is about 4 times the
1685 size of the UTF8 serialization of this document (exmple the XML-1.0
1686 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1687 memory when parsed). Validation will add a amount of memory required for
1688 maintaining the external Dtd state which should be linear with the
1689 complexity of the content model defined by the Dtd</li>
1690 <li>If you don't care about the advanced features of libxml like
1691 validation, DOM, XPath or XPointer, but really need to work fixed memory
1692 requirements, then the SAX interface should be used.</li>
1693</ul>
1694
1695<p></p>
1696
1697<h2><a name="Encodings">Encodings support</a></h2>
1698
1699<p>Table of Content:</p>
1700<ol>
1701 <li><a href="encoding.html#What">What does internationalization support
1702 mean ?</a></li>
1703 <li><a href="encoding.html#internal">The internal encoding, how and
1704 why</a></li>
1705 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1706 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1707 <li><a href="encoding.html#extend">How to extend the existing
1708 support</a></li>
1709</ol>
1710
1711<h3><a name="What">What does internationalization support mean ?</a></h3>
1712
1713<p>XML was designed from the start to allow the support of any character set
1714by using Unicode. Any conformant XML parser has to support the UTF-8 and
1715UTF-16 default encodings which can both express the full unicode ranges. UTF8
1716is a variable length encoding whose greatest point are to resuse the same
1717emcoding for ASCII and to save space for Western encodings, but it is a bit
1718more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1719sometimes combines two pairs), it makes implementation easier, but looks a
1720bit overkill for Western languages encoding. Moreover the XML specification
1721allows document to be encoded in other encodings at the condition that they
1722are clearly labelled as such. For example the following is a wellformed XML
1723document encoded in ISO-8859 1 and using accentuated letter that we French
1724likes for both markup and content:</p>
1725<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1726&lt;très&gt;là&lt;/très&gt;</pre>
1727
1728<p>Having internationalization support in libxml means the foolowing:</p>
1729<ul>
1730 <li>the document is properly parsed</li>
1731 <li>informations about it's encoding are saved</li>
1732 <li>it can be modified</li>
1733 <li>it can be saved in its original encoding</li>
1734 <li>it can also be saved in another encoding supported by libxml (for
1735 example straight UTF8 or even an ASCII form)</li>
1736</ul>
1737
1738<p>Another very important point is that the whole libxml API, with the
1739exception of a few routines to read with a specific encoding or save to a
1740specific encoding, is completely agnostic about the original encoding of the
1741document.</p>
1742
1743<p>It should be noted too that the HTML parser embedded in libxml now obbey
1744the same rules too, the following document will be (as of 2.2.2) handled in
1745an internationalized fashion by libxml too:</p>
1746<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1747 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1748&lt;html lang="fr"&gt;
1749&lt;head&gt;
1750 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1751&lt;/head&gt;
1752&lt;body&gt;
1753&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1754&lt;/html&gt;</pre>
1755
1756<h3><a name="internal">The internal encoding, how and why</a></h3>
1757
1758<p>One of the core decision was to force all documents to be converted to a
1759default internal encoding, and that encoding to be UTF-8, here are the
1760rationale for those choices:</p>
1761<ul>
1762 <li>keeping the native encoding in the internal form would force the libxml
1763 users (or the code associated) to be fully aware of the encoding of the
1764 original document, for examples when adding a text node to a document,
1765 the content would have to be provided in the document encoding, i.e. the
1766 client code would have to check it before hand, make sure it's conformant
1767 to the encoding, etc ... Very hard in practice, though in some specific
1768 cases this may make sense.</li>
1769 <li>the second decision was which encoding. From the XML spec only UTF8 and
1770 UTF16 really makes sense as being the two only encodings for which there
1771 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1772 considered an intelligent choice too since it's a direct Unicode mapping
1773 support. I selected UTF-8 on the basis of efficiency and compatibility
1774 with surrounding software:
1775 <ul>
1776 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1777 more costly to import and export CPU wise) is also far more compact
1778 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1779 for right now (RPM RDF catalogs, advogato data, various configuration
1780 file formats, etc.) and the key point for today's computer
1781 architecture is efficient uses of caches. If one nearly double the
1782 memory requirement to store the same amount of data, this will trash
1783 caches (main memory/external caches/internal caches) and my take is
1784 that this harms the system far more than the CPU requirements needed
1785 for the conversion to UTF-8</li>
1786 <li>Most of libxml version 1 users were using it with straight ASCII
1787 most of the time, doing the conversion with an internal encoding
1788 requiring all their code to be rewritten was a serious show-stopper
1789 for using UTF-16 or UCS-4.</li>
1790 <li>UTF-8 is being used as the de-facto internal encoding standard for
1791 related code like the <a href="http://www.pango.org/">pango</a>
1792 upcoming Gnome text widget, and a lot of Unix code (yep another place
1793 where Unix programmer base takes a different approach from Microsoft
1794 - they are using UTF-16)</li>
1795 </ul>
1796 </li>
1797</ul>
1798
1799<p>What does this mean in practice for the libxml user:</p>
1800<ul>
1801 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1802 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1803 is simply to append 0 byte, as usual.</li>
1804 <li>One just need to make sure that when using chars outside the ASCII set,
1805 the values has been properly converted to UTF-8</li>
1806</ul>
1807
1808<h3><a name="implemente">How is it implemented ?</a></h3>
1809
1810<p>Let's describe how all this works within libxml, basically the I18N
1811(internationalization) support get triggered only during I/O operation, i.e.
1812when reading a document or saving one. Let's look first at the reading
1813sequence:</p>
1814<ol>
1815 <li>when a document is processed, we usually don't know the encoding, a
1816 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1817 ASCII range (0-0x7F) maps with ASCII</li>
1818 <li>the xml declaration if available is parsed, including the encoding
1819 declaration. At that point, if the autodetected encoding is different
1820 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1821 <li>If there is no encoding declaration, then the input has to be in either
1822 UTF-8 or UTF-16, if it is not then at some point when processing the
1823 input, the converter/checker of UTF-8 form will raise an encoding error.
1824 You may end-up with a garbled document, or no document at all ! Example:
1825 <pre>~/XML -&gt; ./xmllint err.xml
1826err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1827&lt;très&gt;là&lt;/très&gt;
1828 ^
1829err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1830&lt;très&gt;là&lt;/très&gt;
1831 ^</pre>
1832 </li>
1833 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1834 then search the default registered encoding converters for that encoding.
1835 If it's not within the default set and iconv() support has been compiled
1836 it, it will ask iconv for such an encoder. If this fails then the parser
1837 will report an error and stops processing:
1838 <pre>~/XML -&gt; ./xmllint err2.xml
1839err2.xml:1: error: Unsupported encoding UnsupportedEnc
1840&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1841 ^</pre>
1842 </li>
1843 <li>From that point the encoder process progressingly the input (it is
1844 plugged as a front-end to the I/O module) for that entity. It captures
1845 and convert on-the-fly the document to be parsed to UTF-8. The parser
1846 itself just does UTF-8 checking of this input and process it
1847 transparently. The only difference is that the encoding information has
1848 been added to the parsing context (more precisely to the input
1849 corresponding to this entity).</li>
1850 <li>The result (when using DOM) is an internal form completely in UTF-8
1851 with just an encoding information on the document node.</li>
1852</ol>
1853
1854<p>Ok then what's happen when saving the document (assuming you
1855colllected/built an xmlDoc DOM like structure) ? It depends on the function
1856called, xmlSaveFile() will just try to save in the original encoding, while
1857xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1858encoding:</p>
1859<ol>
1860 <li>if no encoding is given, libxml will look for an encoding value
1861 associated to the document and if it exists will try to save to that
1862 encoding,
1863 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1864 </li>
1865 <li>so if an encoding was specified, either at the API level or on the
1866 document, libxml will again canonalize the encoding name, lookup for a
1867 converter in the registered set or through iconv. If not found the
1868 function will return an error code</li>
1869 <li>the converter is placed before the I/O buffer layer, as another kind of
1870 buffer, then libxml will simply push the UTF-8 serialization to through
1871 that buffer, which will then progressively be converted and pushed onto
1872 the I/O layer.</li>
1873 <li>It is possible that the converter code fails on some input, for example
1874 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1875 ISO-8859-1 converter won't work. Since the encoders are progressive they
1876 will just report the error and the number of bytes converted, at that
1877 point libxml will decode the offending character, remove it from the
1878 buffer and replace it with the associated charRef encoding &amp;#123; and
1879 resume the convertion. This guarante that any document will be saved
1880 without losses (except for markup names where this is not legal, this is
1881 a problem in the current version, in pactice avoid using non-ascci
1882 characters for tags or attributes names @@). A special "ascii" encoding
1883 name is used to save documents to a pure ascii form can be used when
1884 portability is really crucial</li>
1885</ol>
1886
1887<p>Here is a few examples based on the same test document:</p>
1888<pre>~/XML -&gt; ./xmllint isolat1
1889&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1890&lt;très&gt;là&lt;/très&gt;
1891~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1892&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1893&lt;très&gt;là  &lt;/très&gt;
1894~/XML -&gt; </pre>
1895
1896<p>The same processing is applied (and reuse most of the code) for HTML I18N
1897processing. Looking up and modifying the content encoding is a bit more
1898difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1899so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1900been provided. The parser also attempts to switch encoding on the fly when
1901detecting such a tag on input. Except for that the processing is the same
1902(and again reuses the same code).</p>
1903
1904<h3><a name="Default">Default supported encodings</a></h3>
1905
1906<p>libxml has a set of default converters for the following encodings
1907(located in encoding.c):</p>
1908<ol>
1909 <li>UTF-8 is supported by default (null handlers)</li>
1910 <li>UTF-16, both little and big endian</li>
1911 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1912 <li>ASCII, useful mostly for saving</li>
1913 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1914 predefined entities like &amp;copy; for the Copyright sign.</li>
1915</ol>
1916
1917<p>More over when compiled on an Unix platfor with iconv support the full set
1918of encodings supported by iconv can be instantly be used by libxml. On a
1919linux machine with glibc-2.1 the list of supported encodings and aliases fill
19203 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1921various Japanese ones.</p>
1922
1923<h4>Encoding aliases</h4>
1924
1925<p>From 2.2.3, libxml has support to register encoding names aliases. The
1926goal is to be able to parse document whose encoding is supported but where
1927the name differs (for example from the default set of names accepted by
1928iconv). The following functions allow to register and handle new aliases for
1929existing encodings. Once registered libxml will automatically lookup the
1930aliases when handling a document:</p>
1931<ul>
1932 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1933 <li>int xmlDelEncodingAlias(const char *alias);</li>
1934 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1935 <li>void xmlCleanupEncodingAliases(void);</li>
1936</ul>
1937
1938<h3><a name="extend">How to extend the existing support</a></h3>
1939
1940<p>Well adding support for new encoding, or overriding one of the encoders
1941(assuming it is buggy) should not be hard, just write an input and output
1942conversion routines to/from UTF-8, and register them using
1943xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1944called automatically if the parser(s) encounter such an encoding name
1945(register it uppercase, this will help). The description of the encoders,
1946their arguments and expected return values are described in the encoding.h
1947header.</p>
1948
1949<p>A quick note on the topic of subverting the parser to use a different
1950internal encoding than UTF-8, in some case people will absolutely want to
1951keep the internal encoding different, I think it's still possible (but the
1952encoding must be compliant with ASCII on the same subrange) though I didn't
1953tried it. The key is to override the default conversion routines (by
1954registering null encoders/decoders for your charsets), and bypass the UTF-8
1955checking of the parser by setting the parser context charset
1956(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
1957there is no guarantee taht this will work. You may also have some troubles
1958saving back.</p>
1959
1960<p>Basically proper I18N support is important, this requires at least
1961libxml-2.0.0, but a lot of features and corrections are really available only
1962starting 2.2.</p>
1963
1964<h2><a name="IO">I/O Interfaces</a></h2>
1965
1966<p>Table of Content:</p>
1967<ol>
1968 <li><a href="#General1">General overview</a></li>
1969 <li><a href="#basic">The basic buffer type</a></li>
1970 <li><a href="#Input">Input I/O handlers</a></li>
1971 <li><a href="#Output">Output I/O handlers</a></li>
1972 <li><a href="#entities">The entities loader</a></li>
1973 <li><a href="#Example2">Example of customized I/O</a></li>
1974</ol>
1975
1976<h3><a name="General1">General overview</a></h3>
1977
1978<p>The module <code><a
1979href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
1980the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
1981<ul>
1982 <li>Entities loader, this is a routine which tries to fetch the entities
1983 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
1984 don't look at the public identifier since libxml do not maintain a
1985 catalog. You can redefine you own entity loader by using
1986 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]1987 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
1988 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1989 <li>Input I/O buffers which are a commodity structure used by the parser(s)
1990 input layer to handle fetching the informations to feed the parser. This
1991 provides buffering and is also a placeholder where the encoding
1992 convertors to UTF8 are piggy-backed.</li>
1993 <li>Output I/O buffers are similar to the Input ones and fulfill similar
1994 task but when generating a serialization from a tree.</li>
1995 <li>A mechanism to register sets of I/O callbacks and associate them with
1996 specific naming schemes like the protocol part of the URIs.
1997 <p>This affect the default I/O operations and allows to use specific I/O
1998 handlers for certain names.</p>
1999 </li>
2000</ul>
2001
2002<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2003example in the HTML parser is the following:</p>
2004<ol>
2005 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2006 the parsing context and the URI string.</li>
2007 <li>the URI string is checked against the existing registered handlers
2008 using their match() callback function, if the HTTP module was compiled
2009 in, it is registered and its match() function will succeeds</li>
2010 <li>the open() function of the handler is called and if successful will
2011 return an I/O Input buffer</li>
2012 <li>the parser will the start reading from this buffer and progressively
2013 fetch information from the resource, calling the read() function of the
2014 handler until the resource is exhausted</li>
2015 <li>if an encoding change is detected it will be installed on the input
2016 buffer, providing buffering and efficient use of the conversion
2017 routines</li>
2018 <li>once the parser has finished, the close() function of the handler is
2019 called once and the Input buffer and associed resources are
2020 deallocated.</li>
2021</ol>
2022
2023<p>The user defined callbacks are checked first to allow overriding of the
2024default libxml I/O routines.</p>
2025
2026<h3><a name="basic">The basic buffer type</a></h3>
2027
2028<p>All the buffer manipulation handling is done using the
2029<code>xmlBuffer</code> type define in <code><a
2030href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2031resizable memory buffer. The buffer allocation strategy can be selected to be
2032either best-fit or use an exponential doubling one (CPU vs. memory use
2033tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2034<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2035system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2036of functions allows to manipulate buffers with names starting with the
2037<code>xmlBuffer...</code> prefix.</p>
2038
2039<h3><a name="Input">Input I/O handlers</a></h3>
2040
2041<p>An Input I/O handler is a simple structure
2042<code>xmlParserInputBuffer</code> containing a context associated to the
2043resource (file descriptor, or pointer to a protocol handler), the read() and
2044close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2045encoding handler are also present to support charset conversion when
2046needed.</p>
2047
2048<h3><a name="Output">Output I/O handlers</a></h3>
2049
2050<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2051Input one except the callbacks are write() and close().</p>
2052
2053<h3><a name="entities">The entities loader</a></h3>
2054
2055<p>The entity loader resolves requests for new entities and create inputs for
2056the parser. Creating an input from a filename or an URI string is done
2057through the xmlNewInputFromFile() routine. The default entity loader do not
2058handle the PUBLIC identifier associated with an entity (if any). So it just
2059calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2060XML).</p>
2061
2062<p>If you want to hook up a catalog mechanism then you simply need to
2063override the default entity loader, here is an example:</p>
2064<pre>#include &lt;libxml/xmlIO.h&gt;
2065
2066xmlExternalEntityLoader defaultLoader = NULL;
2067
2068xmlParserInputPtr
2069xmlMyExternalEntityLoader(const char *URL, const char *ID,
2070 xmlParserCtxtPtr ctxt) {
2071 xmlParserInputPtr ret;
2072 const char *fileID = NULL;
2073 /* lookup for the fileID depending on ID */
2074
2075 ret = xmlNewInputFromFile(ctxt, fileID);
2076 if (ret != NULL)
2077 return(ret);
2078 if (defaultLoader != NULL)
2079 ret = defaultLoader(URL, ID, ctxt);
2080 return(ret);
2081}
2082
2083int main(..) {
2084 ...
2085
2086 /*
2087 * Install our own entity loader
2088 */
2089 defaultLoader = xmlGetExternalEntityLoader();
2090 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2091
2092 ...
2093}</pre>
2094
2095<h3><a name="Example2">Example of customized I/O</a></h3>
2096
2097<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2098real use case</a>, xmlDocDump() closes the FILE * passed by the application
2099and this was a problem. The <a
2100href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2101new output handler with the closing call deactivated:</p>
2102<ol>
2103 <li>First define a new I/O ouput allocator where the output don't close the
2104 file:
2105 <pre>xmlOutputBufferPtr
2106xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2107    xmlOutputBufferPtr ret;
2108    
2109    if (xmlOutputCallbackInitialized == 0)
2110        xmlRegisterDefaultOutputCallbacks();
2111
2112    if (file == NULL) return(NULL);
2113    ret = xmlAllocOutputBuffer(encoder);
2114    if (ret != NULL) {
2115        ret-&gt;context = file;
2116        ret-&gt;writecallback = xmlFileWrite;
2117        ret-&gt;closecallback = NULL; /* No close callback */
2118    }
2119    return(ret); <br>
2120
2121
2122
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame]2123
2124
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]2125
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame^]2126
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2127} </pre>
2128 </li>
2129 <li>And then use it to save the document:
2130 <pre>FILE *f;
2131xmlOutputBufferPtr output;
2132xmlDocPtr doc;
2133int res;
2134
2135f = ...
2136doc = ....
2137
2138output = xmlOutputBufferCreateOwn(f, NULL);
2139res = xmlSaveFileTo(output, doc, NULL);
2140 </pre>
2141 </li>
2142</ol>
2143
2144<h2><a name="Catalog">Catalog support</a></h2>
2145
2146<p>Table of Content:</p>
2147<ol>
2148 <li><a href="General2">General overview</a></li>
2149 <li><a href="#definition">The definition</a></li>
2150 <li><a href="#Simple">Using catalogs</a></li>
2151 <li><a href="#Some">Some examples</a></li>
2152 <li><a href="#reference">How to tune catalog usage</a></li>
2153 <li><a href="#validate">How to debug catalog processing</a></li>
2154 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2155 <li><a href="#implemento">The implementor corner quick review of the
2156 API</a></li>
2157 <li><a href="#Other">Other resources</a></li>
2158</ol>
2159
2160<h3><a name="General2">General overview</a></h3>
2161
2162<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2163(a file or a remote resource) references another entity. The catalog lookup
2164is inserted between the moment the reference is recognized by the software
2165(XML parser, stylesheet processing, or even images referenced for inclusion
2166in a rendering) and the time where loading that resource is actually
2167started.</p>
2168
2169<p>It is basically used for 3 things:</p>
2170<ul>
2171 <li>mapping from "logical" names, the public identifiers and a more
2172 concrete name usable for download (and URI). For example it can associate
2173 the logical name
2174 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2175 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2176 downloaded</p>
2177 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2178 </li>
2179 <li>remapping from a given URL to another one, like an HTTP indirection
2180 saying that
2181 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2182 <p>should really be looked at</p>
2183 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2184 </li>
2185 <li>providing a local cache mechanism allowing to load the entities
2186 associated to public identifiers or remote resources, this is a really
2187 important feature for any significant deployment of XML or SGML since it
2188 allows to avoid the aleas and delays associated to fetching remote
2189 resources.</li>
2190</ul>
2191
2192<h3><a name="definition">The definitions</a></h3>
2193
2194<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2195<ul>
2196 <li>the older SGML catalogs, the official spec is SGML Open Technical
2197 Resolution TR9401:1997, but is better understood by reading <a
2198 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2199 James Clark. This is relatively old and not the preferred mode of
2200 operation of libxml.</li>
2201 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2202 Catalogs</a>
2203 is far more flexible, more recent, uses an XML syntax and should scale
2204 quite better. This is the default option of libxml.</li>
2205</ul>
2206
2207<p></p>
2208
2209<h3><a name="Simple">Using catalog</a></h3>
2210
2211<p>In a normal environment libxml will by default check the presence of a
2212catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2213the processing is completely transparent to the document user. To take a
2214concrete example, suppose you are authoring a DocBook document, this one
2215starts with the following DOCTYPE definition:</p>
2216<pre>&lt;?xml version='1.0'?&gt;
2217&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2218 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2219
2220<p>When validating the document with libxml, the catalog will be
2221automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2222DocBk XML V3.1.4//EN" and the system identifier
2223"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2224been installed on your system and the catalogs actually point to them, libxml
2225will fetch them from the local disk.</p>
2226
2227<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2228DOCTYPE example it's a really old version, but is fine as an example.</p>
2229
2230<p>Libxml will check the catalog each time that it is requested to load an
2231entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2232your system is correctly configured all the authoring phase and processing
2233should use only local files, even if your document stays portable because it
2234uses the canonical public and system ID, referencing the remote document.</p>
2235
2236<h3><a name="Some">Some examples:</a></h3>
2237
2238<p>Here is a couple of fragments from XML Catalogs used in libxml early
2239regression tests in <code>test/catalogs</code> :</p>
2240<pre>&lt;?xml version="1.0"?&gt;
2241&lt;!DOCTYPE catalog PUBLIC
2242 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2243 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2244&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2245 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2246 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2247...</pre>
2248
2249<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2250written in XML, there is a specific namespace for catalog elements
2251"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2252catalog is a <code>public</code> mapping it allows to associate a Public
2253Identifier with an URI.</p>
2254<pre>...
2255 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2256 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2257...</pre>
2258
2259<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2260any URI starting with a given prefix should be looked at another URI
2261constructed by replacing the prefix with an new one. In effect this acts like
2262a cache system for a full area of the Web. In practice it is extremely useful
2263with a file prefix if you have installed a copy of those resources on your
2264local system.</p>
2265<pre>...
2266&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2267 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2268&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2269 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2270&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2271 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2272&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2273 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2274&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2275 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2276...</pre>
2277
2278<p>Delegation is the core features which allows to build a tree of catalogs,
2279easier to maintain than a single catalog, based on Public Identifier, System
2280Identifier or URI prefixes it instructs the catalog software to look up
2281entries in another resource. This feature allow to build hierarchies of
2282catalogs, the set of entries presented should be sufficient to redirect the
2283resolution of all DocBook references to the specific catalog in
2284<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2285references for DocBook 4.2.1 to a specific catalog installed at the same time
2286as the DocBook resources on the local machine.</p>
2287
2288<h3><a name="reference">How to tune catalog usage:</a></h3>
2289
2290<p>The user can change the default catalog behaviour by redirecting queries
2291to its own set of catalogs, this can be done by setting the
2292<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2293empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2294default catalog</p>
2295
2296<h3><a name="validate">How to debug catalog processing:</a></h3>
2297
2298<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2299make libxml output debugging informations for each catalog operations, for
2300example:</p>
2301<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2302warning: failed to load external entity "title.xml"
2303orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2304orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2305Failed to parse catalog /etc/xml/catalog
2306Failed to parse catalog /etc/xml/catalog
2307warning: failed to load external entity "title.xml"
2308Catalogs cleanup
2309orchis:~/XML -&gt; </pre>
2310
2311<p>The test/ent2 references an entity, running the parser from memory makes
2312the base URI unavailable and the the "title.xml" entity cannot be loaded.
2313Setting up the debug environment variable allows to detect that an attempt is
2314made to load the <code>/etc/xml/catalog</code> but since it's not present the
2315resolution fails.</p>
2316
2317<p>But the most advanced way to debug XML catalog processing is to use the
2318<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2319catalogs and make resolution queries to see what is going on. This is also
2320used for the regression tests:</p>
2321<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2322 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2323http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2324orchis:~/XML -&gt; </pre>
2325
2326<p>For debugging what is going on, adding one -v flags increase the verbosity
2327level to indicate the processing done (adding a second flag also indicate
2328what elements are recognized at parsing):</p>
2329<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2330 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2331Parsing catalog test/catalogs/docbook.xml's content
2332Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2333http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2334Catalogs cleanup
2335orchis:~/XML -&gt; </pre>
2336
2337<p>A shell interface is also available to debug and process multiple queries
2338(and for regression tests):</p>
2339<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2340 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2341&gt; help
2342Commands available:
2343public PublicID: make a PUBLIC identifier lookup
2344system SystemID: make a SYSTEM identifier lookup
2345resolve PublicID SystemID: do a full resolver lookup
2346add 'type' 'orig' 'replace' : add an entry
2347del 'values' : remove values
2348dump: print the current catalog state
2349debug: increase the verbosity level
2350quiet: decrease the verbosity level
2351exit: quit the shell
2352&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2353http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2354&gt; quit
2355orchis:~/XML -&gt; </pre>
2356
2357<p>This should be sufficient for most debugging purpose, this was actually
2358used heavily to debug the XML Catalog implementation itself.</p>
2359
2360<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2361
2362<p>Basically XML Catalogs are XML files, you can either use XML tools to
2363manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2364to create a catalog the -create option provide this facility:</p>
2365<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2366&lt;?xml version="1.0"?&gt;
2367&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2368 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2369&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2370orchis:~/XML -&gt; </pre>
2371
2372<p>By default xmlcatalog does not overwrite the original catalog and save the
2373result on the standard output, this can be overridden using the -noout
2374option. The <code>-add</code> command allows to add entries in the
2375catalog:</p>
2376<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2377 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2378 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2379orchis:~/XML -&gt; cat tst.xml
2380&lt;?xml version="1.0"?&gt;
2381&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2382 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2383&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2384&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2385 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2386&lt;/catalog&gt;
2387orchis:~/XML -&gt; </pre>
2388
2389<p>The <code>-add</code> option will always take 3 parameters even if some of
2390the XML Catalog constructs (like nextCatalog) will have only a single
2391argument, just pass a third empty string, it will be ignored.</p>
2392
2393<p>Similarly the <code>-del</code> option remove matching entries from the
2394catalog:</p>
2395<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2396 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2397&lt;?xml version="1.0"?&gt;
2398&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2399 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2400&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2401orchis:~/XML -&gt; </pre>
2402
2403<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2404exact and would have worked in a similar fashion with the Public ID
2405string.</p>
2406
2407<p>This is rudimentary but should be sufficient to manage a not too complex
2408catalog tree of resources.</p>
2409
2410<h3><a name="implemento">The implementor corner quick review of the
2411API:</a></h3>
2412
2413<p>First, and like for every other module of libxml, there is an
2414automatically generated <a href="html/libxml-catalog.html">API page for
2415catalog support</a>.</p>
2416
2417<p>The header for the catalog interfaces should be included as:</p>
2418<pre>#include &lt;libxml/catalog.h&gt;</pre>
2419
2420<p>The API is voluntarily kept very simple. First it is not obvious that
2421applications really need access to it since it is the default behaviour of
2422libxml (Note: it is possible to completely override libxml default catalog by
2423using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2424plug an application specific resolver).</p>
2425
2426<p>Basically libxml support 2 catalog lists:</p>
2427<ul>
2428 <li>the default one, global shared by all the application</li>
2429 <li>a per-document catalog, this one is built if the document uses the
2430 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2431 associated to the parser context and destroyed when the parsing context
2432 is destroyed.</li>
2433</ul>
2434
2435<p>the document one will be used first if it exists.</p>
2436
2437<h4>Initialization routines:</h4>
2438
2439<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2440used at startup to initialize the catalog, if the catalog should be
2441initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2442should be called before xmlInitializeCatalog() which would otherwise do a
2443default initialization first.</p>
2444
2445<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2446own catalog list if needed.</p>
2447
2448<h4>Preferences setup:</h4>
2449
2450<p>The XML Catalog spec requires the possibility to select default
2451preferences between public and system delegation,
2452xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2453xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2454be forbidden, allowed for global catalog, for document catalog or both, the
2455default is to allow both.</p>
2456
2457<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2458(through the xmlGenericError() mechanism).</p>
2459
2460<h4>Querying routines:</h4>
2461
2462<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2463and xmlCatalogResolveURI() are relatively explicit if you read the XML
2464Catalog specification they correspond to section 7 algorithms, they should
2465also work if you have loaded an SGML catalog with a simplified semantic.</p>
2466
2467<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2468operate on the document catalog list</p>
2469
2470<h4>Cleanup and Miscellaneous:</h4>
2471
2472<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2473the per-document equivalent.</p>
2474
2475<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2476first catalog in the global list, and xmlCatalogDump() allows to dump a
2477catalog state, those routines are primarily designed for xmlcatalog, I'm not
2478sure that exposing more complex interfaces (like navigation ones) would be
2479really useful.</p>
2480
2481<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2482it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2483provided because this functionality may be useful for client tools.</p>
2484
2485<h4>threaded environments:</h4>
2486
2487<p>Since the catalog tree is built progressively, some care has been taken to
2488try to avoid troubles in multithreaded environments. The code is now thread
2489safe assuming that the libxml library has been compiled with threads
2490support.</p>
2491
2492<p></p>
2493
2494<h3><a name="Other">Other resources</a></h3>
2495
2496<p>The XML Catalog specification is relatively recent so there isn't much
2497literature to point at:</p>
2498<ul>
2499 <li>You can find an good rant from Norm Walsh about <a
2500 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2501 need for catalogs</a>, it provides a lot of context informations even if
2502 I don't agree with everything presented.</li>
2503 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2504 catalog proposal</a> from John Cowan</li>
2505 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2506 Language</a> (RDDL) another catalog system but more oriented toward
2507 providing metadata for XML namespaces.</li>
2508 <li>the page from the OASIS Technical <a
2509 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2510 Resolution</a> who maintains XML Catalog, you will find pointers to the
2511 specification update, some background and pointers to others tools
2512 providing XML Catalog support</li>
2513 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2514 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2515 work fine for me</li>
2516 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2517 manual page</a></li>
2518</ul>
2519
2520<p>If you have suggestions for corrections or additions, simply contact
2521me:</p>
2522
2523<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2524
2525<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2526using the XML library from the C language. It is not intended to be
2527extensive. I hope the automatically generated documents will provide the
2528completeness required, but as a separate set of documents. The interfaces of
2529the XML library are by principle low level, there is nearly zero abstraction.
2530Those interested in a higher level API should <a href="#DOM">look at
2531DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2532
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2533<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2534separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2535interfaces</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]2536
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2537<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2538
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2539<p>Usually, the first thing to do is to read an XML input. The parser accepts
2540documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2541defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2542<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2543 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2544 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2545 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2546</dl>
2547<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2548 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2549 <dd><p>Parse an XML document contained in a (possibly compressed)
2550 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2551 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2552</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2553
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2554<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]2555failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2556
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2557<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2558
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2559<p>In order for the application to keep the control when the document is
2560being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2561interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2562<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2563 void *user_data,
2564 const char *chunk,
2565 int size,
2566 const char *filename);
2567int xmlParseChunk (xmlParserCtxtPtr ctxt,
2568 const char *chunk,
2569 int size,
2570 int terminate);</pre>
2571
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2572<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2573<pre> FILE *f;
2574
2575 f = fopen(filename, "r");
2576 if (f != NULL) {
2577 int res, size = 1024;
2578 char chars[1024];
2579 xmlParserCtxtPtr ctxt;
2580
2581 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2582 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2583 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2584 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2585 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2586 xmlParseChunk(ctxt, chars, res, 0);
2587 }
2588 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2589 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2590 xmlFreeParserCtxt(ctxt);
2591 }
2592 }</pre>
2593
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2594<p>The HTML parser embedded into libxml also has a push interface; the
2595functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2596
2597<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2598
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2599<p>The tree-building interface makes the parser memory-hungry, first loading
2600the document in memory and then building the tree itself. Reading a document
2601without building the tree is possible using the SAX interfaces (see SAX.h and
2602<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]2603Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2604limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2605<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2606
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2607<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2608
2609<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]2610there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2611also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2612code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2613<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2614 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2615 xmlNodePtr tree, subtree;
2616
2617 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2618 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2619 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2620 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2621 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2622 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2623 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2624 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2625 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2626 subtree = xmlNewChild(tree, NULL, "image", NULL);
2627 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2628
2629<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2630
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2631<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2632
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2633<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2634code has access to the internal structure of all the elements of the tree.
2635The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2636<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2637<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2638example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2639<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2640
2641<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2642<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2643
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2644<p>points to the text node containing the chapter title "The Linux
2645adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2646
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2647<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]2648present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2649to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2650<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2651
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2652<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2653
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2654<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2655is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2656<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2657 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2658 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2659 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2660 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2661 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2662</dl>
2663<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2664 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2665 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2666 <dd><p>This function returns a pointer to new copy of the property
2667 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2668 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2669</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2670
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2671<p>Two functions are provided for reading and writing the text associated
2672with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2673<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2674 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2675 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2676 <dd><p>This function takes an "external" string and converts it to one
2677 text node or possibly to a list of entity and text nodes. All
2678 non-predefined entity references like &amp;Gnome; will be stored
2679 internally as entity nodes, hence the result of the function may not be
2680 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2681 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2682</dl>
2683<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2684 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2685 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2686 <dd><p>This function is the inverse of
2687 <code>xmlStringGetNodeList()</code>. It generates a new string
2688 containing the content of the text and entity nodes. Note the extra
2689 argument inLine. If this argument is set to 1, the function will expand
2690 entity references. For example, instead of returning the &amp;Gnome;
2691 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2692 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2693 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2694</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2695
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2696<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2697
2698<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2699<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2700 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2701 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2702 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2703 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2704</dl>
2705<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2706 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2707 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2708 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2709</dl>
2710<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2711 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2712 <dd><p>Saves the document to a file. In this case, the compression
2713 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2714 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2715</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2716
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2717<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2718
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2719<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2720accesses. The level of compression on saves can be turned on either globally
2721or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2722<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2723 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2724 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2725 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2726</dl>
2727<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2728 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2729 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2730 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2731</dl>
2732<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2733 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2734 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2735 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2736</dl>
2737<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2738 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2739 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2740 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2741</dl>
2742
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2743<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2744
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2745<p>Entities in principle are similar to simple C macros. An entity defines an
2746abbreviation for a given string that you can reuse many times throughout the
2747content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2748may occur frequently within a document, or to confine the change needed to a
2749document to a restricted area in the internal subset of the document (at the
2750beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2751<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27522 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27533 &lt;!ENTITY xml "Extensible Markup Language"&gt;
27544 ]&gt;
27555 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27566 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27577 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2758
2759<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]2760its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2761are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2762predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2763<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2764for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2765<strong>&amp;quot;</strong> for the character '"', and
2766<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2767
2768<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]2769substitute an entity's content so that you can see the replacement text in
2770your application. Or you may prefer to keep entity references as such in the
2771content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2772precious information (if the user went through the pain of explicitly
2773defining entities, he may have a a rather negative attitude if you blindly
2774susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2775href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2776function allows you to check and change the behaviour, which is to not
2777substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2778
2779<p>Here is the DOM tree built by libxml for the previous document in the
2780default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2781<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2782DOCUMENT
2783version=1.0
2784 ELEMENT EXAMPLE
2785 TEXT
2786 content=
2787 ENTITY_REF
2788 INTERNAL_GENERAL_ENTITY xml
2789 content=Extensible Markup Language
2790 TEXT
2791 content=</pre>
2792
2793<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2794<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2795DOCUMENT
2796version=1.0
2797 ELEMENT EXAMPLE
2798 TEXT
2799 content= Extensible Markup Language</pre>
2800
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2801<p>So, entities or no entities? Basically, it depends on your use case. I
2802suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2803entities in your XML document or data if you are not willing to handle the
2804entity references elements in the DOM tree.</p>
2805
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2806<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2807entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2808transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2809reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2810finding them in the input).</p>
2811
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2812<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2813on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2814non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2815then 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]2816strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2817deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2818
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2819<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2820
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2821<p>The libxml library implements <a
2822href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2823recognizing namespace contructs in the input, and does namespace lookup
2824automatically when building the DOM tree. A namespace declaration is
2825associated with an in-memory structure and all elements or attributes within
2826that namespace point to it. Hence testing the namespace is a simple and fast
2827equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2828
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2829<p>I suggest that people using libxml use a namespace, and declare it in the
2830root element of their document as the default namespace. Then they don't need
2831to 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]2832refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2833the size of the XML output significantly, but significantly increases its
2834value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2835<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2836 &lt;elem1&gt;...&lt;/elem1&gt;
2837 &lt;elem2&gt;...&lt;/elem2&gt;
2838&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2839
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2840<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2841point to any existing resource on the Web. It will bind all the element and
2842atributes with that URL. I suggest to use an URL within a domain you control,
2843and that the URL should contain some kind of version information if possible.
2844For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2845namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2846
2847<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2848version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2849and if the version information don't match something you know, warn the user
2850and 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]2851namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2852same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2853associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2854just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2855<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2856prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2857
2858<p>@@Interfaces@@</p>
2859
2860<p>@@Examples@@</p>
2861
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2862<p>Usually people object to using namespaces together with validity checking.
2863I will try to make sure that using namespaces won't break validity checking,
2864so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2865suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2866<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2867flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2868from multiple DTDs will certainly break current validation schemes. I will
2869try to provide ways to do this, but this may not be portable or
2870standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2871
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2872<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2873
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2874<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2875
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2876<p>Version 2 of libxml is the first version introducing serious backward
2877incompatible changes. The main goals were:</p>
2878<ul>
2879 <li>a general cleanup. A number of mistakes inherited from the very early
2880 versions couldn't be changed due to compatibility constraints. Example
2881 the "childs" element in the nodes.</li>
2882 <li>Uniformization of the various nodes, at least for their header and link
2883 parts (doc, parent, children, prev, next), the goal is a simpler
2884 programming model and simplifying the task of the DOM implementors.</li>
2885 <li>better conformances to the XML specification, for example version 1.x
2886 had an heuristic to try to detect ignorable white spaces. As a result the
2887 SAX event generated were ignorableWhitespace() while the spec requires
2888 character() in that case. This also mean that a number of DOM node
2889 containing blank text may populate the DOM tree which were not present
2890 before.</li>
2891</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2892
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2893<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2894
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2895<p>So client code of libxml designed to run with version 1.x may have to be
2896changed to compile against version 2.x of libxml. Here is a list of changes
2897that I have collected, they may not be sufficient, so in case you find other
2898change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2899mail</a>:</p>
2900<ol>
2901 <li>The package name have changed from libxml to libxml2, the library name
2902 is now -lxml2 . There is a new xml2-config script which should be used to
2903 select the right parameters libxml2</li>
2904 <li>Node <strong>childs</strong> field has been renamed
2905 <strong>children</strong> so s/childs/children/g should be applied
2906 (probablility of having "childs" anywere else is close to 0+</li>
2907 <li>The document don't have anymore a <strong>root</strong> element it has
2908 been replaced by <strong>children</strong> and usually you will get a
2909 list of element here. For example a Dtd element for the internal subset
2910 and it's declaration may be found in that list, as well as processing
2911 instructions or comments found before or after the document root element.
2912 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2913 a document. Alternatively if you are sure to not reference Dtds nor have
2914 PIs or comments before or after the root element
2915 s/-&gt;root/-&gt;children/g will probably do it.</li>
2916 <li>The white space issue, this one is more complex, unless special case of
2917 validating parsing, the line breaks and spaces usually used for indenting
2918 and formatting the document content becomes significant. So they are
2919 reported by SAX and if your using the DOM tree, corresponding nodes are
2920 generated. Too approach can be taken:
2921 <ol>
2922 <li>lazy one, use the compatibility call
2923 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2924 relying on a special (and possibly broken) set of heuristics of
2925 libxml to detect ignorable blanks. Don't complain if it breaks or
2926 make your application not 100% clean w.r.t. to it's input.</li>
2927 <li>the Right Way: change you code to accept possibly unsignificant
2928 blanks characters, or have your tree populated with weird blank text
2929 nodes. You can spot them using the comodity function
2930 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2931 nodes.</li>
2932 </ol>
2933 <p>Note also that with the new default the output functions don't add any
2934 extra indentation when saving a tree in order to be able to round trip
2935 (read and save) without inflating the document with extra formatting
2936 chars.</p>
2937 </li>
2938 <li>The include path has changed to $prefix/libxml/ and the includes
2939 themselves uses this new prefix in includes instructions... If you are
2940 using (as expected) the
2941 <pre>xml2-config --cflags</pre>
2942 <p>output to generate you compile commands this will probably work out of
2943 the box</p>
2944 </li>
2945 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2946 byte of the head of the document available for character detection.</li>
2947</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2948
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2949<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2950
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2951<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
2952to allow smoth upgrade of existing libxml v1code while retaining
2953compatibility. They offers the following:</p>
2954<ol>
2955 <li>similar include naming, one should use
2956 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
2957 <li>similar identifiers defined via macros for the child and root fields:
2958 respectively <strong>xmlChildrenNode</strong> and
2959 <strong>xmlRootNode</strong></li>
2960 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
2961 inserted once in the client code</li>
2962</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2963
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2964<p>So the roadmap to upgrade your existing libxml applications is the
2965following:</p>
2966<ol>
2967 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
2968 <li>find all occurences where the xmlDoc <strong>root</strong> field is
2969 used and change it to <strong>xmlRootNode</strong></li>
2970 <li>similary find all occurences where the xmlNode <strong>childs</strong>
2971 field is used and change it to <strong>xmlChildrenNode</strong></li>
2972 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
2973 <strong>main()</strong> or in the library init entry point</li>
2974 <li>Recompile, check compatibility, it should still work</li>
2975 <li>Change your configure script to look first for xml2-config and fallback
2976 using xml-config . Use the --cflags and --libs ouptut of the command as
2977 the Include and Linking parameters needed to use libxml.</li>
2978 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
2979 libxml-devel-1.8.y can be kept simultaneously)</li>
2980 <li>remove your config.cache, relaunch your configuration mechanism, and
2981 recompile, if steps 2 and 3 were done right it should compile as-is</li>
2982 <li>Test that your application is still running correctly, if not this may
2983 be due to extra empty nodes due to formating spaces being kept in libxml2
2984 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
2985 code before calling the parser (next to
2986 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
2987</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2988
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2989<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]2990
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2991<p>Let me put some emphasis on the fact that there is far more changes from
2992libxml 1.x to 2.x than the ones you may have to patch for. The overall code
2993has been considerably cleaned up and the conformance to the XML specification
2994has been drastically improved too. Don't take those changes as an excuse to
2995not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2996
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]2997<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2998
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2999<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
3000Object Model</em>; this is an API for accessing XML or HTML structured
3001documents. Native support for DOM in Gnome is on the way (module gnome-dom),
3002and will be based on gnome-xml. This will be a far cleaner interface to
3003manipulate XML files within Gnome since it won't expose the internal
3004structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3005
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3006<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3007href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3008is a full DOM interface, thanks to Paolo Casarini, check the <a
3009href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3010informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3011
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3012<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3013
3014<p>Here is a real size example, where the actual content of the application
3015data 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]3016a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3017storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3018base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3019<pre>&lt;?xml version="1.0"?&gt;
3020&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3021 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3022
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3023 &lt;gjob:Job&gt;
3024 &lt;gjob:Project ID="3"/&gt;
3025 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3026 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3027
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3028 &lt;gjob:Update&gt;
3029 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3030 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3031 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3032 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3033
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3034 &lt;gjob:Developers&gt;
3035 &lt;gjob:Developer&gt;
3036 &lt;/gjob:Developer&gt;
3037 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3038
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3039 &lt;gjob:Contact&gt;
3040 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3041 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3042 &lt;gjob:Company&gt;
3043 &lt;/gjob:Company&gt;
3044 &lt;gjob:Organisation&gt;
3045 &lt;/gjob:Organisation&gt;
3046 &lt;gjob:Webpage&gt;
3047 &lt;/gjob:Webpage&gt;
3048 &lt;gjob:Snailmail&gt;
3049 &lt;/gjob:Snailmail&gt;
3050 &lt;gjob:Phone&gt;
3051 &lt;/gjob:Phone&gt;
3052 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3053
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3054 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3055 The program should be released as free software, under the GPL.
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
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3058 &lt;gjob:Skills&gt;
3059 &lt;/gjob:Skills&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3060
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3061 &lt;gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3062 A GNOME based system that will allow a superuser to configure
3063 compressed and uncompressed files and/or file systems to be backed
3064 up with a supported media in the system. This should be able to
3065 perform via find commands generating a list of files that are passed
3066 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3067 or via operations performed on the filesystem itself. Email
3068 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3069 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3070
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3071 &lt;/gjob:Job&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:Jobs&gt;
3074&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3075
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3076<p>While loading the XML file into an internal DOM tree is a matter of
3077calling only a couple of functions, browsing the tree to gather the ata and
3078generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3079
3080<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3081structure. For example, the ordering of the attributes is not significant,
3082the 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]3083depend on the order of the children of a given node, unless it really makes
3084things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3085<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3086 * A person record
3087 */
3088typedef struct person {
3089 char *name;
3090 char *email;
3091 char *company;
3092 char *organisation;
3093 char *smail;
3094 char *webPage;
3095 char *phone;
3096} person, *personPtr;
3097
3098/*
3099 * And the code needed to parse it
3100 */
3101personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3102 personPtr ret = NULL;
3103
3104DEBUG("parsePerson\n");
3105 /*
3106 * allocate the struct
3107 */
3108 ret = (personPtr) malloc(sizeof(person));
3109 if (ret == NULL) {
3110 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3111 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3112 }
3113 memset(ret, 0, sizeof(person));
3114
3115 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3116 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3117 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3118 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3119 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3120 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3121 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3122 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3123 }
3124
3125 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3126}</pre>
3127
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3128<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3129<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3130 <li>Usually a recursive parsing style is the more convenient one: XML data
3131 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3132 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3133 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3134 i.e. the pointer to the global XML document and the namespace reserved to
3135 the application. Document wide information are needed for example to
3136 decode entities and it's a good coding practice to define a namespace for
3137 your application set of data and test that the element and attributes
3138 you're analyzing actually pertains to your application space. This is
3139 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3140 <li>To retrieve text and attributes value, you can use the function
3141 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3142 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3143</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3144
3145<p>Here is another piece of code used to parse another level of the
3146structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3147<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3148/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3149 * a Description for a Job
3150 */
3151typedef struct job {
3152 char *projectID;
3153 char *application;
3154 char *category;
3155 personPtr contact;
3156 int nbDevelopers;
3157 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3158} job, *jobPtr;
3159
3160/*
3161 * And the code needed to parse it
3162 */
3163jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3164 jobPtr ret = NULL;
3165
3166DEBUG("parseJob\n");
3167 /*
3168 * allocate the struct
3169 */
3170 ret = (jobPtr) malloc(sizeof(job));
3171 if (ret == NULL) {
3172 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3173 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3174 }
3175 memset(ret, 0, sizeof(job));
3176
3177 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3178 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3179 while (cur != NULL) {
3180
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3181 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3182 ret-&gt;projectID = xmlGetProp(cur, "ID");
3183 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3184 fprintf(stderr, "Project has no ID\n");
3185 }
3186 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3187 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3188 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3189 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3190 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3191 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3192 ret-&gt;contact = parsePerson(doc, ns, cur);
3193 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3194 }
3195
3196 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3197}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3198
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3199<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]3200boring. Ultimately, it could be possble to write stubbers taking either C
3201data structure definitions, a set of XML examples or an XML DTD and produce
3202the code needed to import and export the content between C data and XML
3203storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3204
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3205<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3206parsing example</a> as a template, it is also available with Makefile in the
3207Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3208
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3209<h2><a name="Contributi">Contributions</a></h2>
3210<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3211 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3212 patches, Gary Pennington worked on the validation API, threading support
3213 and Solaris port.</li>
3214 <li>John Fleck helps maintaining the documentation and man pages.</li>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3215 <li><a href="mailto:ari@lusis.org">Ari Johnson</a>
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame^]3216 provides a C++ wrapper for libxml:<br>
Daniel Veillardc6271d22001-10-27 07:50:58 +0000[diff] [blame]3217 Website: <a
3218 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
3219 Download: <a
Daniel Veillard51095312001-10-28 18:51:57 +0000[diff] [blame^]3220 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3221 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3222 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3223 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3224 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3225 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3226 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3227 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3228 <li><a
3229 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3230 Sergeant</a>
3231 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3232 wrapper for libxml2/libxslt as part of the <a
3233 href="http://axkit.com/">AxKit XML application server</a></li>
3234 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3235 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3236 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3237 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3238 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3239 provided <a href="http://xmlsoft.org/messages/0488.html">man
3240 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3241 <li>there is a module for <a
3242 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3243 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3244 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3245 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3246 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3247</ul>
3248
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3249<p></p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3250</body>
3251</html>