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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>
36 : Uniform Resource Identifiers <a
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>
64 : libxml implements a basic FTP client code</li>
65 <li><a href="http://www.cis.ohio-state.edu/rfc/rfc1945.txt">RFC 1945</a>
66 : HTTP/1.0, again a basic HTTP client code</li>
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 Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame^]77 <li><a href="http://xmlsoft.org/XSLT/">the libxslt page</a> providing an
78 implementation of XSLT 1.0 and extensions on top of libxml2</li>
79 <li><a href="http://www.cs.unibo.it/~casarini/gdome2/">the gdome2 page</a>:
80 a standard DOM2 implementation based on libxml2</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]81</ul>
82
83<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]84
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]85<p>This document describes libxml, the <a
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]86href="http://www.w3.org/XML/">XML</a> C library developped for the <a
87href="http://www.gnome.org/">Gnome</a> project. <a
88href="http://www.w3.org/XML/">XML is a standard</a> for building tag-based
89structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]90
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]91<p>Here are some key points about libxml:</p>
92<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]93 <li>Libxml exports Push and Pull type parser interfaces for both XML and
94 HTML.</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]95 <li>Libxml can do DTD validation at parse time, using a parsed document
96 instance, or with an arbitrary DTD.</li>
97 <li>Libxml now includes nearly complete <a
Daniel Veillard8c2ecaf2001-07-10 17:53:07 +0000[diff] [blame]98 href="http://www.w3.org/TR/xpath">XPath</a>, <a
99 href="http://www.w3.org/TR/xptr">XPointer</a> and <a
100 href="http://www.w3.org/TR/xinclude">XInclude</a> implementations.</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]101 <li>It is written in plain C, making as few assumptions as possible, and
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]102 sticking closely to ANSI C/POSIX for easy embedding. Works on
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]103 Linux/Unix/Windows, ported to a number of other platforms.</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]104 <li>Basic support for HTTP and FTP client allowing aplications to fetch
105 remote resources</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]106 <li>The design is modular, most of the extensions can be compiled out.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]107 <li>The internal document repesentation is as close as possible to the <a
108 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
109 <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]110 like interface</a>; the interface is designed to be compatible with <a
111 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]112 <li>This library is released both under the <a
113 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]114 IPR</a> and the <a href="http://www.gnu.org/copyleft/lesser.html">GNU
115 LGPL</a>. Use either at your convenience, basically this should make
116 everybody happy, if not, drop me a mail.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]117</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]118
Daniel Veillarde0c1d722001-03-21 10:28:36 +0000[diff] [blame]119<p>Warning: unless you are forced to because your application links with a
120Gnome library requiring it, <strong><span
121style="background-color: #FF0000">Do Not Use libxml1</span></strong>, use
122libxml2</p>
123
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]124<h2><a name="FAQ">FAQ</a></h2>
125
126<p>Table of Content:</p>
127<ul>
128 <li><a href="FAQ.html#Licence">Licence(s)</a></li>
129 <li><a href="FAQ.html#Installati">Installation</a></li>
130 <li><a href="FAQ.html#Compilatio">Compilation</a></li>
131 <li><a href="FAQ.html#Developer">Developer corner</a></li>
132</ul>
133
134<h3><a name="Licence">Licence</a>(s)</h3>
135<ol>
136 <li><em>Licensing Terms for libxml</em>
137 <p>libxml is released under 2 (compatible) licences:</p>
138 <ul>
139 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
140 Library General Public License</li>
141 <li>the <a
142 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
143 IPR</a>: very similar to the XWindow licence</li>
144 </ul>
145 </li>
146 <li><em>Can I embed libxml in a proprietary application ?</em>
147 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
148 made to libxml, but it would be graceful to provide back bugfixes and
149 improvements as patches for possible incorporation in the main
150 development tree</p>
151 </li>
152</ol>
153
154<h3><a name="Installati">Installation</a></h3>
155<ol>
156 <li>Unless you are forced to because your application links with a Gnome
157 library requiring it, <strong><span style="background-color: #FF0000">Do
158 Not Use libxml1</span></strong>, use libxml2</li>
159 <li><em>Where can I get libxml</em>
160 ?
161 <p>The original distribution comes from <a
162 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
163 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
164 <p>Most linux and Bsd distribution includes libxml, this is probably the
165 safer way for end-users</p>
166 <p>David Doolin provides precompiled Windows versions at <a
167 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
168 </li>
169 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
170 <ul>
171 <li>If you are not concerned by any existing backward compatibility
172 with existing application, install libxml2 only</li>
173 <li>If you are not doing development, you can safely install both.
174 usually the packages <a
175 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
176 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
177 compatible (this is not the case for development packages)</li>
178 <li>If you are a developer and your system provides separate packaging
179 for shared libraries and the development components, it is possible
180 to install libxml and libxml2, and also <a
181 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
182 and <a
183 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
184 too for libxml2 &gt;= 2.3.0</li>
185 <li>If you are developing a new application, please develop against
186 libxml2(-devel)</li>
187 </ul>
188 </li>
189 <li><em>I can't install the libxml package it conflicts with libxml0</em>
190 <p>You probably have an old libxml0 package used to provide the shared
191 library for libxml.so.0, you can probably safely remove it. Anyway the
192 libxml packages provided on <a
193 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
194 libxml.so.0</p>
195 </li>
196 <li><em>I can't install the libxml(2) RPM package due to failed
197 dependancies</em>
198 <p>The most generic solution is to refetch the latest src.rpm , and
199 rebuild it locally with</p>
200 <p><code>rpm --rebuild libxml(2)-xxx.src.rpm</code></p>
201 <p>if everything goes well it will generate two binary rpm (one providing
202 the shared libs and xmllint, and the other one, the -devel package
203 providing includes, static libraries and scripts needed to build
204 applications with libxml(2)) that you can install locally.</p>
205 </li>
206</ol>
207
208<h3><a name="Compilatio">Compilation</a></h3>
209<ol>
210 <li><em>What is the process to compile libxml ?</em>
211 <p>As most UNIX libraries libxml follows the "standard":</p>
212 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
213 <p><code>cd libxml-xxxx</code></p>
214 <p><code>./configure --help</code></p>
215 <p>to see the options, then the compilation/installation proper</p>
216 <p><code>./configure [possible options]</code></p>
217 <p><code>make</code></p>
218 <p><code>make install</code></p>
219 <p>At that point you may have to rerun ldconfig or similar utility to
220 update your list of installed shared libs.</p>
221 </li>
222 <li><em>What other libraries are needed to compile/install libxml ?</em>
223 <p>Libxml does not requires any other library, the normal C ANSI API
224 should be sufficient (please report any violation to this rule you may
225 find).</p>
226 <p>However if found at configuration time libxml will detect and use the
227 following libs:</p>
228 <ul>
229 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>
230 : a highly portable and available widely compression library</li>
231 <li>iconv: a powerful character encoding conversion library. It's
232 included by default on recent glibc libraries, so it doesn't need to
233 be installed specifically on linux. It seems it's now <a
234 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part
235 of the official UNIX</a> specification. Here is one <a
236 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
237 of the library</a> which source can be found <a
238 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
239 </ul>
240 </li>
241 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
242 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
243 CFLAGS</p>
244 <p>you can also install and use gcc instead or use a precompiled version
245 of libxml, both available from the <a
246 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
247 and Archive Centre</a></p>
248 </li>
249 <li><em>make check fails on some platforms</em>
250 <p>Sometime the regression tests results don't completely match the value
251 produced by the parser, and the makefile uses diff to print the delta. On
252 some platforms the diff return breaks the compilation process, if the
253 diff is small this is probably not a serious problem</p>
254 </li>
255 <li><em>I use the CVS version and there is no configure script</em>
256 <p>The configure (and other Makefiles) are generated. Use the autogen.sh
257 script to regenerate the configure and Makefiles, like:</p>
258 <p><code>./autogen.sh --prefix=/usr --disable-shared</code></p>
259 </li>
260 <li><em>I have troubles when running make tests with gcc-3.0</em>
261 <p>It seems the initial release of gcc-3.0 has a problem with the
262 optimizer which miscompiles the URI module. Please use another
263 compiler</p>
264 </li>
265</ol>
266
267<h3><a name="Developer">Developer</a> corner</h3>
268<ol>
269 <li><em>xmlDocDump() generates output on one line</em>
270 <p>libxml will not <strong>invent</strong> spaces in the content of a
271 document since <strong>all spaces in the content of a document are
272 significant</strong>. If you build a tree from the API and want
273 indentation:</p>
274 <ol>
275 <li>the correct way is to generate those yourself too</li>
276 <li>the dangerous way is to ask libxml to add those blanks to your
277 content <strong>modifying the content of your document in the
278 process</strong>. The result may not be what you expect. There is
279 <strong>NO</strong> way to guarantee that such a modification won't
280 impact other part of the content of your document. See <a
281 href="http://xmlsoft.org/html/libxml-parser.html#XMLKEEPBLANKSDEFAULT">xmlKeepBlanksDefault
282 ()</a> and <a
283 href="http://xmlsoft.org/html/libxml-tree.html#XMLSAVEFORMATFILE">xmlSaveFormatFile
284 ()</a></li>
285 </ol>
286 </li>
287 <li>Extra nodes in the document:
288 <p><em>For a XML file as below:</em></p>
289 <pre>&lt;?xml version="1.0"?&gt;
290&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
291&lt;NODE CommFlag="0"/&gt;
292&lt;NODE CommFlag="1"/&gt;
293&lt;/PLAN&gt;</pre>
294 <p><em>after parsing it with the function
295 pxmlDoc=xmlParseFile(...);</em></p>
296 <p><em>I want to the get the content of the first node (node with the
297 CommFlag="0")</em></p>
298 <p><em>so I did it as following;</em></p>
299 <pre>xmlNodePtr pode;
300pnode=pxmlDoc-&gt;children-&gt;children;</pre>
301 <p><em>but it does not work. If I change it to</em></p>
302 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
303 <p><em>then it works. Can someone explain it to me.</em></p>
304 <p></p>
305 <p>In XML all characters in the content of the document are significant
306 <strong>including blanks and formatting line breaks</strong>.</p>
307 <p>The extra nodes you are wondering about are just that, text nodes with
308 the formatting spaces wich are part of the document but that people tend
309 to forget. There is a function <a
310 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
311 ()</a> to remove those at parse time, but that's an heuristic, and its
312 use should be limited to case where you are sure there is no
313 mixed-content in the document.</p>
314 </li>
315 <li><em>I get compilation errors of existing code like when accessing
316 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
317 <p>You are compiling code developed for libxml version 1 and using a
318 libxml2 development environment. Either switch back to libxml v1 devel or
319 even better fix the code to compile with libxml2 (or both) by <a
320 href="upgrade.html">following the instructions</a>.</p>
321 </li>
322 <li><em>I get compilation errors about non existing
323 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
324 fields</em>
325 <p>The source code you are using has been <a
326 href="upgrade.html">upgraded</a> to be able to compile with both libxml
327 and libxml2, but you need to install a more recent version:
328 libxml(-devel) &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
329 </li>
330 <li><em>XPath implementation looks seriously broken</em>
331 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to
332 a recent version, the implementation and debug of libxslt generated fixes
333 for most obvious problems.</p>
334 </li>
335 <li><em>The example provided in the web page does not compile</em>
336 <p>It's hard to maintain the documentation in sync with the code
337 &lt;grin/&gt; ...</p>
338 <p>Check the previous points 1/ and 2/ raised before, and send
339 patches.</p>
340 </li>
341 <li><em>Where can I get more examples and informations than in the web
342 page</em>
343 <p>Ideally a libxml book would be nice. I have no such plan ... But you
344 can:</p>
345 <ul>
346 <li>check more deeply the <a href="html/libxml-lib.html">existing
347 generated doc</a></li>
348 <li>looks for examples of use for libxml function using the Gnome code
349 for example the following will query the full Gnome CVs base for the
350 use of the <strong>xmlAddChild()</strong> function:
351 <p><a
352 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
353 <p>This may be slow, a large hardware donation to the gnome project
354 could cure this :-)</p>
355 </li>
356 <li><a
357 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
358 the libxml source</a>
359 , I try to write code as clean and documented as possible, so
360 looking at it may be helpful</li>
361 </ul>
362 </li>
363 <li>What about C++ ?
364 <p>libxml is written in pure C in order to allow easy reuse on a number
365 of platforms, including embedded systems. I don't intend to convert to
366 C++.</p>
367 <p>There is however a C++ wrapper provided by Ari Johnson
368 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
369 <p>Website: <a
370 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
371 <p>Download: <a
372 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
373 </li>
374 <li>How to validate a document a posteriori ?
375 <p>It is possible to validate documents which had not been validated at
376 initial parsing time or documents who have been built from scratch using
377 the API. Use the <a
378 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
379 function. It is also possible to simply add a Dtd to an existing
380 document:</p>
381 <pre>xmlDocPtr doc; /* your existing document */
382 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
383 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
384
385 doc-&gt;intSubset = dtd;
386 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
387 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
388 </pre>
389 </li>
390 <li>etc ...</li>
391</ol>
392
393<p></p>
394
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]395<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]396
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]397<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]398<ol>
Daniel Veillard365e13b2000-07-02 07:56:37 +0000[diff] [blame]399 <li>Check the <a href="FAQ.html">FAQ</a></li>
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]400 <li>Check the <a href="http://xmlsoft.org/html/libxml-lib.html">extensive
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]401 documentation</a> automatically extracted from code comments (using <a
402 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gtk-doc">gtk
403 doc</a>).</li>
Daniel Veillard8d869642000-07-14 12:12:59 +0000[diff] [blame]404 <li>Look at the documentation about <a href="encoding.html">libxml
405 internationalization support</a></li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]406 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]407 examples</a> on how to use libxml.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]408 <li><a href="mailto:james@daa.com.au">James Henstridge</a>
409 wrote <a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]410 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
411 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]412 <li>George Lebl wrote <a
413 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]414 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]415 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
416 file</a></li>
417 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
418 starting a new project using libxml you should really use the 2.x
419 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]420 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]421 archive</a>.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]422</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]423
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]424<h2><a name="Reporting">Reporting bugs and getting help</a></h2>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]425
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]426<p>Well, bugs or missing features are always possible, and I will make a
427point of fixing them in a timely fashion. The best way to report a bug is to
428use the <a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome
429bug tracking database</a> (make sure to use the "libxml" module name). I look
430at reports there regularly and it's good to have a reminder when a bug is
431still open. Check the <a
432href="http://bugzilla.gnome.org/bugwritinghelp.html">instructions on
433reporting bugs</a> and be sure to specify that the bug is for the package
434libxml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]435
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]436<p>There is also a mailing-list <a
Daniel Veillard3197f162001-04-04 00:40:08 +0000[diff] [blame]437href="mailto:xml@gnome.org">xml@gnome.org</a> for libxml, with an <a
438href="http://mail.gnome.org/archives/xml/">on-line archive</a> (<a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]439href="http://xmlsoft.org/messages">old</a>). To subscribe to this list,
440please visit the <a
441href="http://mail.gnome.org/mailman/listinfo/xml">associated Web</a> page and
442follow the instructions. <strong>Do not send code, I won't debug it</strong>
443(but patches are really appreciated!).</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]444
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]445<p>Check the following <strong><span style="color: #FF0000">before
446posting</span></strong>:</p>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]447<ul>
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]448 <li>read the <a href="FAQ.html">FAQ</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]449 <li>make sure you are <a href="ftp://xmlsoft.org/">using a recent
450 version</a>, and that the problem still shows up in those</li>
451 <li>check the <a href="http://mail.gnome.org/archives/xml/">list
452 archives</a> to see if the problem was reported already, in this case
Daniel Veillarde7ead2d2001-08-22 23:44:09 +0000[diff] [blame]453 there is probably a fix available, similary check the <a
454 href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">registered
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]455 open bugs</a></li>
Daniel Veillard234547b2001-07-05 09:46:10 +0000[diff] [blame]456 <li>make sure you can reproduce the bug with xmllint or one of the test
457 programs found in source in the distribution</li>
458 <li>Please send the command showing the error as well as the input (as an
459 attachement)</li>
460</ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]461
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]462<p>Then send the bug with associated informations to reproduce it to the <a
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]463href="mailto:xml@gnome.org">xml@gnome.org</a> list; if it's really libxml
Daniel Veillard008186f2001-09-13 14:24:44 +0000[diff] [blame]464related I will approve it.. Please do not send me mail directly, it makes
465things really harder to track and in some cases I'm not the best person to
466answer a given question, ask the list instead.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]467
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]468<p>Of course, bugs reported with a suggested patch for fixing them will
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]469probably be processed faster.</p>
470
471<p>If you're looking for help, a quick look at <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]472href="http://mail.gnome.org/archives/xml/">the list archive</a> may actually
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]473provide the answer, I usually send source samples when answering libxml usage
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]474questions. The <a href="http://xmlsoft.org/html/book1.html">auto-generated
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]475documentantion</a> is not as polished as I would like (i need to learn more
476about Docbook), but it's a good starting point.</p>
477
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]478<h2><a name="help">How to help</a></h2>
479
480<p>You can help the project in various ways, the best thing to do first is to
481subscribe to the mailing-list as explained before, check the <a
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]482href="http://mail.gnome.org/archives/xml/">archives </a>and the <a
483href="http://bugzilla.gnome.org/buglist.cgi?product=libxml">Gnome bug
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]484database:</a>:</p>
485<ol>
486 <li>provide patches when you find problems</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]487 <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]488 be integrated in all cases but help pinpointing portability problems
489 and</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]490 <li>provide documentation fixes (either as patches to the code comments or
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]491 as HTML diffs).</li>
492 <li>provide new documentations pieces (translations, examples, etc ...)</li>
493 <li>Check the TODO file and try to close one of the items</li>
494 <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]495 provide a fix. <a href="mailto:daniel@veillard.com">Get in touch with me
496 </a>before to avoid synchronization problems and check that the suggested
497 fix will fit in nicely :-)</li>
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]498</ol>
499
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]500<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]501
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]502<p>The latest versions of libxml can be found on <a
Daniel Veillard20c8cf22001-06-26 22:47:36 +0000[diff] [blame]503href="ftp://xmlsoft.org/">xmlsoft.org</a> (<a
504href="ftp://speakeasy.rpmfind.net/pub/libxml/">Seattle</a>, <a
505href="ftp://fr.rpmfind.net/pub/libxml/">France</a>) or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]506href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]507as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]508archive</a> or <a
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]509href="ftp://ftp.gnome.org/pub/GNOME/stable/redhat/i386/libxml/">RPM
510packages</a>. (NOTE that you need both the <a
Daniel Veillardc19fccc2000-07-03 11:52:01 +0000[diff] [blame]511href="http://rpmfind.net/linux/RPM/libxml2.html">libxml(2)</a> and <a
512href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml(2)-devel</a>
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]513packages installed to compile applications using libxml.) <a
514href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a> is now the maintainer
515of the Windows port, <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]516href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
517provides 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
527<p><a name="Contribs">Contribs:</a></p>
528
529<p>I do accept external contributions, especially if compiling on another
530platform, get in touch with me to upload the package. I will keep them in the
Daniel Veillard33a67802001-03-07 09:44:02 +0000[diff] [blame]531<a href="ftp://xmlsoft.org/contribs/">contrib directory</a></p>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]532
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]533<p>Libxml is also available from CVS:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]534<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]535 <li><p>The <a
536 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]537 CVS base</a>. Check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]538 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a>
539 page; the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]540 </li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]541 <li>The <strong>libxslt</strong> module is also present there</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]542</ul>
543
544<h2><a name="News">News</a></h2>
545
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]546<h3>CVS only : check the <a
547href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]548for a really accurate description</h3>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]549
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]550<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]551you want to test those</p>
552<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]553 <li>Implementing <a href="http://xmlsoft.org/XSLT">XSLT</a>, this is done
554 as a separate C library on top of libxml called libxslt</li>
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]555 <li>Finishing up <a href="http://www.w3.org/TR/xptr">XPointer</a> and <a
556 href="http://www.w3.org/TR/xinclude">XInclude</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]557 <li>(seeems working but delayed from release) parsing/import of Docbook
558 SGML docs</li>
559</ul>
560
Daniel Veillard60087f32001-10-10 09:45:09 +0000[diff] [blame]561<h3>2.4.6: Oct 10 2001</h3>
562<ul>
563 <li>added and updated man pages by John Fleck</li>
564 <li>portability and configure fixes</li>
565 <li>an infinite loop on the HTML parser was removed (William)</li>
566 <li>Windows makefile patches from Igor</li>
567 <li>fixed half a dozen bugs reported fof libxml or libxslt</li>
568 <li>updated xmlcatalog to be able to modify SGML super catalogs</li>
569</ul>
570
Daniel Veillarddadd0872001-09-15 09:21:44 +0000[diff] [blame]571<h3>2.4.5: Sep 14 2001</h3>
572<ul>
573 <li>Remove a few annoying bugs in 2.4.4</li>
574 <li>forces the HTML serializer to output decimal charrefs since some
575 version of Netscape can't handle hexadecimal ones</li>
576</ul>
577
578<h3>1.8.16: Sep 14 2001</h3>
579<ul>
580 <li>maintenance release of the old libxml1 branch, couple of bug and
581 portability fixes</li>
582</ul>
583
Daniel Veillard04382ae2001-09-12 18:51:30 +0000[diff] [blame]584<h3>2.4.4: Sep 12 2001</h3>
585<ul>
586 <li>added --convert to xmlcatalog, bug fixes and cleanups of XML
587 Catalog</li>
588 <li>a few bug fixes and some portability changes</li>
589 <li>some documentation cleanups</li>
590</ul>
591
Daniel Veillard39936902001-08-24 00:49:01 +0000[diff] [blame]592<h3>2.4.3: Aug 23 2001</h3>
593<ul>
594 <li>XML Catalog support see the doc</li>
595 <li>New NaN/Infinity floating point code</li>
596 <li>A few bug fixes</li>
597</ul>
598
599<h3>2.4.2: Aug 15 2001</h3>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]600<ul>
601 <li>adds xmlLineNumbersDefault() to control line number generation</li>
602 <li>lot of bug fixes</li>
603 <li>the Microsoft MSC projects files shuld now be up to date</li>
604 <li>inheritance of namespaces from DTD defaulted attributes</li>
605 <li>fixes a serious potential security bug</li>
606 <li>added a --format option to xmllint</li>
607</ul>
608
609<h3>2.4.1: July 24 2001</h3>
610<ul>
611 <li>possibility to keep line numbers in the tree</li>
612 <li>some computation NaN fixes</li>
613 <li>extension of the XPath API</li>
614 <li>cleanup for alpha and ia64 targets</li>
615 <li>patch to allow saving through HTTP PUT or POST</li>
Daniel Veillard09ab7e12001-07-10 15:49:44 +0000[diff] [blame]616</ul>
617
618<h3>2.4.0: July 10 2001</h3>
619<ul>
620 <li>Fixed a few bugs in XPath, validation, and tree handling.</li>
621 <li>Fixed XML Base implementation, added a coupel of examples to the
622 regression tests</li>
623 <li>A bit of cleanup</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]624</ul>
625
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]626<h3>2.3.14: July 5 2001</h3>
627<ul>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]628 <li>fixed some entities problems and reduce mem requirement when
629 substituing them</li>
Daniel Veillard5b43fde2001-07-05 23:31:40 +0000[diff] [blame]630 <li>lots of improvements in the XPath queries interpreter can be
631 substancially faster</li>
632 <li>Makefiles and configure cleanups</li>
633 <li>Fixes to XPath variable eval, and compare on empty node set</li>
634 <li>HTML tag closing bug fixed</li>
635 <li>Fixed an URI reference computating problem when validating</li>
636</ul>
637
Daniel Veillard2adbb512001-06-28 16:20:36 +0000[diff] [blame]638<h3>2.3.13: June 28 2001</h3>
639<ul>
640 <li>2.3.12 configure.in was broken as well as the push mode XML parser</li>
641 <li>a few more fixes for compilation on Windows MSC by Yon Derek</li>
642</ul>
643
644<h3>1.8.14: June 28 2001</h3>
645<ul>
646 <li>Zbigniew Chyla gave a patch to use the old XML parser in push mode</li>
647 <li>Small Makefile fix</li>
648</ul>
649
Daniel Veillard11648102001-06-26 16:08:24 +0000[diff] [blame]650<h3>2.3.12: June 26 2001</h3>
651<ul>
652 <li>lots of cleanup</li>
653 <li>a couple of validation fix</li>
654 <li>fixed line number counting</li>
655 <li>fixed serious problems in the XInclude processing</li>
656 <li>added support for UTF8 BOM at beginning of entities</li>
657 <li>fixed a strange gcc optimizer bugs in xpath handling of float, gcc-3.0
658 miscompile uri.c (William), Thomas Leitner provided a fix for the
659 optimizer on Tru64</li>
660 <li>incorporated Yon Derek and Igor Zlatkovic fixes and improvements for
661 compilation on Windows MSC</li>
662 <li>update of libxml-doc.el (Felix Natter)</li>
663 <li>fixed 2 bugs in URI normalization code</li>
664</ul>
665
Daniel Veillarde3c81b52001-06-17 14:50:34 +0000[diff] [blame]666<h3>2.3.11: June 17 2001</h3>
667<ul>
668 <li>updates to trio, Makefiles and configure should fix some portability
669 problems (alpha)</li>
670 <li>fixed some HTML serialization problems (pre, script, and block/inline
671 handling), added encoding aware APIs, cleanup of this code</li>
672 <li>added xmlHasNsProp()</li>
673 <li>implemented a specific PI for encoding support in the DocBook SGML
674 parser</li>
675 <li>some XPath fixes (-Infinity, / as a function parameter and namespaces
676 node selection)</li>
677 <li>fixed a performance problem and an error in the validation code</li>
678 <li>fixed XInclude routine to implement the recursive behaviour</li>
679 <li>fixed xmlFreeNode problem when libxml is included statically twice</li>
680 <li>added --version to xmllint for bug reports</li>
681</ul>
682
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]683<h3>2.3.10: June 1 2001</h3>
684<ul>
685 <li>fixed the SGML catalog support</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]686 <li>a number of reported bugs got fixed, in XPath, iconv detection,
687 XInclude processing</li>
Daniel Veillard2e4f1882001-06-01 10:11:57 +0000[diff] [blame]688 <li>XPath string function should now handle unicode correctly</li>
689</ul>
690
Daniel Veillard4623acd2001-05-19 15:13:15 +0000[diff] [blame]691<h3>2.3.9: May 19 2001</h3>
692
693<p>Lots of bugfixes, and added a basic SGML catalog support:</p>
694<ul>
695 <li>HTML push bugfix #54891 and another patch from Jonas Borgström</li>
696 <li>some serious speed optimisation again</li>
697 <li>some documentation cleanups</li>
698 <li>trying to get better linking on solaris (-R)</li>
699 <li>XPath API cleanup from Thomas Broyer</li>
700 <li>Validation bug fixed #54631, added a patch from Gary Pennington, fixed
701 xmlValidGetValidElements()</li>
702 <li>Added an INSTALL file</li>
703 <li>Attribute removal added to API: #54433</li>
704 <li>added a basic support for SGML catalogs</li>
705 <li>fixed xmlKeepBlanksDefault(0) API</li>
706 <li>bugfix in xmlNodeGetLang()</li>
707 <li>fixed a small configure portability problem</li>
708 <li>fixed an inversion of SYSTEM and PUBLIC identifier in HTML document</li>
709</ul>
710
Daniel Veillarda265af72001-05-14 11:13:58 +0000[diff] [blame]711<h3>1.8.13: May 14 2001</h3>
712<ul>
713 <li>bugfixes release of the old libxml1 branch used by Gnome</li>
714</ul>
715
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]716<h3>2.3.8: May 3 2001</h3>
717<ul>
718 <li>Integrated an SGML DocBook parser for the Gnome project</li>
719 <li>Fixed a few things in the HTML parser</li>
720 <li>Fixed some XPath bugs raised by XSLT use, tried to fix the floating
721 point portability issue</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]722 <li>Speed improvement (8M/s for SAX, 3M/s for DOM, 1.5M/s for
723 DOM+validation using the XML REC as input and a 700MHz celeron).</li>
Daniel Veillard3bbbe6f2001-05-03 11:15:37 +0000[diff] [blame]724 <li>incorporated more Windows cleanup</li>
725 <li>added xmlSaveFormatFile()</li>
726 <li>fixed problems in copying nodes with entities references (gdome)</li>
727 <li>removed some troubles surrounding the new validation module</li>
728</ul>
729
Daniel Veillarda41123c2001-04-22 19:31:20 +0000[diff] [blame]730<h3>2.3.7: April 22 2001</h3>
731<ul>
732 <li>lots of small bug fixes, corrected XPointer</li>
733 <li>Non determinist content model validation support</li>
734 <li>added xmlDocCopyNode for gdome2</li>
735 <li>revamped the way the HTML parser handles end of tags</li>
736 <li>XPath: corrctions of namespacessupport and number formatting</li>
737 <li>Windows: Igor Zlatkovic patches for MSC compilation</li>
738 <li>HTML ouput fixes from P C Chow and William M. Brack</li>
739 <li>Improved validation speed sensible for DocBook</li>
740 <li>fixed a big bug with ID declared in external parsed entities</li>
741 <li>portability fixes, update of Trio from Bjorn Reese</li>
742</ul>
743
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]744<h3>2.3.6: April 8 2001</h3>
745<ul>
746 <li>Code cleanup using extreme gcc compiler warning options, found and
747 cleared half a dozen potential problem</li>
748 <li>the Eazel team found an XML parser bug</li>
749 <li>cleaned up the user of some of the string formatting function. used the
750 trio library code to provide the one needed when the platform is missing
751 them</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]752 <li>xpath: removed a memory leak and fixed the predicate evaluation
753 problem, extended the testsuite and cleaned up the result. XPointer seems
754 broken ...</li>
Daniel Veillardafc73112001-04-11 11:51:41 +0000[diff] [blame]755</ul>
756
Daniel Veillard56a4cb82001-03-24 17:00:36 +0000[diff] [blame]757<h3>2.3.5: Mar 23 2001</h3>
758<ul>
759 <li>Biggest change is separate parsing and evaluation of XPath expressions,
760 there is some new APIs for this too</li>
761 <li>included a number of bug fixes(XML push parser, 51876, notations,
762 52299)</li>
763 <li>Fixed some portability issues</li>
764</ul>
765
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]766<h3>2.3.4: Mar 10 2001</h3>
767<ul>
768 <li>Fixed bugs #51860 and #51861</li>
769 <li>Added a global variable xmlDefaultBufferSize to allow default buffer
770 size to be application tunable.</li>
771 <li>Some cleanup in the validation code, still a bug left and this part
772 should probably be rewritten to support ambiguous content model :-\</li>
773 <li>Fix a couple of serious bugs introduced or raised by changes in 2.3.3
774 parser</li>
775 <li>Fixed another bug in xmlNodeGetContent()</li>
776 <li>Bjorn fixed XPath node collection and Number formatting</li>
777 <li>Fixed a loop reported in the HTML parsing</li>
778 <li>blank space are reported even if the Dtd content model proves that they
779 are formatting spaces, this is for XmL conformance</li>
780</ul>
781
Daniel Veillardb402c072001-03-01 17:28:58 +0000[diff] [blame]782<h3>2.3.3: Mar 1 2001</h3>
783<ul>
784 <li>small change in XPath for XSLT</li>
785 <li>documentation cleanups</li>
786 <li>fix in validation by Gary Pennington</li>
787 <li>serious parsing performances improvements</li>
788</ul>
789
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]790<h3>2.3.2: Feb 24 2001</h3>
Daniel Veillard71681102001-02-24 17:48:53 +0000[diff] [blame]791<ul>
792 <li>chasing XPath bugs, found a bunch, completed some TODO</li>
793 <li>fixed a Dtd parsing bug</li>
794 <li>fixed a bug in xmlNodeGetContent</li>
795 <li>ID/IDREF support partly rewritten by Gary Pennington</li>
796</ul>
797
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]798<h3>2.3.1: Feb 15 2001</h3>
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]799<ul>
800 <li>some XPath and HTML bug fixes for XSLT</li>
801 <li>small extension of the hash table interfaces for DOM gdome2
802 implementation</li>
803 <li>A few bug fixes</li>
804</ul>
805
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]806<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]807<ul>
808 <li>Lots of XPath bug fixes</li>
809 <li>Add a mode with Dtd lookup but without validation error reporting for
810 XSLT</li>
811 <li>Add support for text node without escaping (XSLT)</li>
812 <li>bug fixes for xmlCheckFilename</li>
813 <li>validation code bug fixes from Gary Pennington</li>
814 <li>Patch from Paul D. Smith correcting URI path normalization</li>
815 <li>Patch to allow simultaneous install of libxml-devel and
816 libxml2-devel</li>
817 <li>the example Makefile is now fixed</li>
818 <li>added HTML to the RPM packages</li>
819 <li>tree copying bugfixes</li>
820 <li>updates to Windows makefiles</li>
821 <li>optimisation patch from Bjorn Reese</li>
822</ul>
823
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]824<h3>2.2.11: Jan 4 2001</h3>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]825<ul>
826 <li>bunch of bug fixes (memory I/O, xpath, ftp/http, ...)</li>
827 <li>added htmlHandleOmittedElem()</li>
828 <li>Applied Bjorn Reese's IPV6 first patch</li>
829 <li>Applied Paul D. Smith patches for validation of XInclude results</li>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]830 <li>added XPointer xmlns() new scheme support</li>
Daniel Veillard503b8932001-01-05 06:36:31 +0000[diff] [blame]831</ul>
832
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]833<h3>2.2.10: Nov 25 2000</h3>
Daniel Veillard9d343c42000-11-25 10:12:43 +0000[diff] [blame]834<ul>
835 <li>Fix the Windows problems of 2.2.8</li>
836 <li>integrate OpenVMS patches</li>
837 <li>better handling of some nasty HTML input</li>
838 <li>Improved the XPointer implementation</li>
839 <li>integrate a number of provided patches</li>
840</ul>
841
Daniel Veillard2ddd23d2000-11-25 10:42:19 +0000[diff] [blame]842<h3>2.2.9: Nov 25 2000</h3>
843<ul>
844 <li>erroneous release :-(</li>
845</ul>
846
Daniel Veillard28929b22000-11-13 18:22:49 +0000[diff] [blame]847<h3>2.2.8: Nov 13 2000</h3>
848<ul>
849 <li>First version of <a href="http://www.w3.org/TR/xinclude">XInclude</a>
850 support</li>
851 <li>Patch in conditional section handling</li>
852 <li>updated MS compiler project</li>
853 <li>fixed some XPath problems</li>
854 <li>added an URI escaping function</li>
855 <li>some other bug fixes</li>
856</ul>
857
858<h3>2.2.7: Oct 31 2000</h3>
859<ul>
860 <li>added message redirection</li>
861 <li>XPath improvements (thanks TOM !)</li>
862 <li>xmlIOParseDTD() added</li>
863 <li>various small fixes in the HTML, URI, HTTP and XPointer support</li>
864 <li>some cleanup of the Makefile, autoconf and the distribution content</li>
865</ul>
866
Daniel Veillard29a11cc2000-10-25 13:32:39 +0000[diff] [blame]867<h3>2.2.6: Oct 25 2000:</h3>
868<ul>
869 <li>Added an hash table module, migrated a number of internal structure to
870 those</li>
871 <li>Fixed a posteriori validation problems</li>
872 <li>HTTP module cleanups</li>
873 <li>HTML parser improvements (tag errors, script/style handling, attribute
874 normalization)</li>
875 <li>coalescing of adjacent text nodes</li>
876 <li>couple of XPath bug fixes, exported the internal API</li>
877</ul>
878
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]879<h3>2.2.5: Oct 15 2000:</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]880<ul>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]881 <li>XPointer implementation and testsuite</li>
882 <li>Lot of XPath fixes, added variable and functions registration, more
883 tests</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]884 <li>Portability fixes, lots of enhancements toward an easy Windows build
885 and release</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]886 <li>Late validation fixes</li>
887 <li>Integrated a lot of contributed patches</li>
888 <li>added memory management docs</li>
Daniel Veillardab8500d2000-10-15 21:06:19 +0000[diff] [blame]889 <li>a performance problem when using large buffer seems fixed</li>
Daniel Veillard189446d2000-10-13 10:23:06 +0000[diff] [blame]890</ul>
891
892<h3>2.2.4: Oct 1 2000:</h3>
893<ul>
894 <li>main XPath problem fixed</li>
895 <li>Integrated portability patches for Windows</li>
896 <li>Serious bug fixes on the URI and HTML code</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]897</ul>
898
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]899<h3>2.2.3: Sep 17 2000</h3>
900<ul>
901 <li>bug fixes</li>
902 <li>cleanup of entity handling code</li>
903 <li>overall review of all loops in the parsers, all sprintf usage has been
904 checked too</li>
905 <li>Far better handling of larges Dtd. Validating against Docbook XML Dtd
906 works smoothly now.</li>
907</ul>
908
909<h3>1.8.10: Sep 6 2000</h3>
910<ul>
911 <li>bug fix release for some Gnome projects</li>
912</ul>
913
914<h3>2.2.2: August 12 2000</h3>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]915<ul>
916 <li>mostly bug fixes</li>
Daniel Veillardec78c0f2000-08-25 10:25:23 +0000[diff] [blame]917 <li>started adding routines to access xml parser context options</li>
Daniel Veillard786d7c82000-08-12 23:38:57 +0000[diff] [blame]918</ul>
919
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]920<h3>2.2.1: July 21 2000</h3>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]921<ul>
922 <li>a purely bug fixes release</li>
923 <li>fixed an encoding support problem when parsing from a memory block</li>
924 <li>fixed a DOCTYPE parsing problem</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]925 <li>removed a bug in the function allowing to override the memory
926 allocation routines</li>
Daniel Veillarda2679fa2000-07-22 02:38:15 +0000[diff] [blame]927</ul>
928
Daniel Veillardd5f97f82000-09-17 16:38:14 +0000[diff] [blame]929<h3>2.2.0: July 14 2000</h3>
Daniel Veillard94e90602000-07-17 14:38:19 +0000[diff] [blame]930<ul>
931 <li>applied a lot of portability fixes</li>
932 <li>better encoding support/cleanup and saving (content is now always
933 encoded in UTF-8)</li>
934 <li>the HTML parser now correctly handles encodings</li>
935 <li>added xmlHasProp()</li>
936 <li>fixed a serious problem with &amp;#38;</li>
937 <li>propagated the fix to FTP client</li>
938 <li>cleanup, bugfixes, etc ...</li>
939 <li>Added a page about <a href="encoding.html">libxml Internationalization
940 support</a></li>
941</ul>
942
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]943<h3>1.8.9: July 9 2000</h3>
944<ul>
945 <li>fixed the spec the RPMs should be better</li>
946 <li>fixed a serious bug in the FTP implementation, released 1.8.9 to solve
947 rpmfind users problem</li>
948</ul>
949
Daniel Veillard6388e172000-07-03 16:07:19 +0000[diff] [blame]950<h3>2.1.1: July 1 2000</h3>
951<ul>
952 <li>fixes a couple of bugs in the 2.1.0 packaging</li>
953 <li>improvements on the HTML parser</li>
954</ul>
955
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]956<h3>2.1.0 and 1.8.8: June 29 2000</h3>
957<ul>
958 <li>1.8.8 is mostly a comodity package for upgrading to libxml2 accoding to
959 <a href="upgrade.html">new instructions</a>. It fixes a nasty problem
960 about &amp;#38; charref parsing</li>
961 <li>2.1.0 also ease the upgrade from libxml v1 to the recent version. it
962 also contains numerous fixes and enhancements:
963 <ul>
964 <li>added xmlStopParser() to stop parsing</li>
965 <li>improved a lot parsing speed when there is large CDATA blocs</li>
966 <li>includes XPath patches provided by Picdar Technology</li>
967 <li>tried to fix as much as possible DtD validation and namespace
968 related problems</li>
969 <li>output to a given encoding has been added/tested</li>
970 <li>lot of various fixes</li>
971 </ul>
972 </li>
973</ul>
974
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]975<h3>2.0.0: Apr 12 2000</h3>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]976<ul>
977 <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]978 idea to check the 1.x to 2.x upgrade instructions. NOTE: while initally
979 scheduled for Apr 3 the relase occured only on Apr 12 due to massive
980 workload.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]981 <li>The include are now located under $prefix/include/libxml (instead of
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]982 $prefix/include/gnome-xml), they also are referenced by
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]983 <pre>#include &lt;libxml/xxx.h&gt;</pre>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]984 <p>instead of</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]985 <pre>#include "xxx.h"</pre>
986 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]987 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
988 <li>the memory allocation routines used by libxml can now be overloaded
989 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]990 <li>The previously CVS only tool tester has been renamed
991 <strong>xmllint</strong> and is now installed as part of the libxml2
992 package</li>
Daniel Veillarde0aed302000-04-16 08:52:20 +0000[diff] [blame]993 <li>The I/O interface has been revamped. There is now ways to plug in
994 specific I/O modules, either at the URI scheme detection level using
995 xmlRegisterInputCallbacks() or by passing I/O functions when creating a
996 parser context using xmlCreateIOParserCtxt()</li>
997 <li>there is a C preprocessor macro LIBXML_VERSION providing the version
998 number of the libxml module in use</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]999 <li>a number of optional features of libxml can now be excluded at
1000 configure time (FTP/HTTP/HTML/XPath/Debug)</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1001</ul>
1002
1003<h3>2.0.0beta: Mar 14 2000</h3>
1004<ul>
1005 <li>This is a first Beta release of libxml version 2</li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]1006 <li>It's available only from<a href="ftp://xmlsoft.org/">xmlsoft.org
1007 FTP</a>, it's packaged as libxml2-2.0.0beta and available as tar and
1008 RPMs</li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1009 <li>This version is now the head in the Gnome CVS base, the old one is
1010 available under the tag LIB_XML_1_X</li>
1011 <li>This includes a very large set of changes. Froma programmatic point of
1012 view applications should not have to be modified too much, check the <a
1013 href="upgrade.html">upgrade page</a></li>
1014 <li>Some interfaces may changes (especially a bit about encoding).</li>
1015 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1016 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1017 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
1018 handled now</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1019 <li>Better handling of entities, especially well formedness checking
1020 and proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1021 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1022 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1023 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
1024 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]1025 </ul>
1026 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]1027 <li>Serious progress were made toward compliance, <a
1028 href="conf/result.html">here are the result of the test</a> against the
1029 OASIS testsuite (except the japanese tests since I don't support that
1030 encoding yet). This URL is rebuilt every couple of hours using the CVS
1031 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1032</ul>
1033
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1034<h3>1.8.7: Mar 6 2000</h3>
1035<ul>
1036 <li>This is a bug fix release:</li>
1037 <li>It is possible to disable the ignorable blanks heuristic used by
1038 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1039 that for adherence to XML spec, this behaviour will be disabled by
1040 default in 2.x . The same function will allow to keep compatibility for
1041 old code.</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1042 <li>Blanks in &lt;a&gt; &lt;/a&gt; constructs are not ignored anymore,
1043 avoiding heuristic is really the Right Way :-\</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1044 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
1045 compilation on some platforms has been fixed</li>
1046 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
1047 URIs</li>
1048</ul>
1049
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]1050<h3>1.8.6: Jan 31 2000</h3>
1051<ul>
1052 <li>added a nanoFTP transport module, debugged until the new version of <a
1053 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
1054 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]1055</ul>
1056
1057<h3>1.8.5: Jan 21 2000</h3>
1058<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1059 <li>adding APIs to parse a well balanced chunk of XML (production <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1060 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the
1061 XML spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1062 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1063 <li>Jody Goldberg &lt;jgoldberg@home.com&gt; provided another patch trying
1064 to solve the zlib checks problems</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]1065 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
1066 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1067</ul>
1068
1069<h3>1.8.4: Jan 13 2000</h3>
1070<ul>
1071 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
1072 <li>all exit() call should have been removed from libxml</li>
1073 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
1074 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1075</ul>
1076
1077<h3>1.8.3: Jan 5 2000</h3>
1078<ul>
1079 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1080 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]1081 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1082 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1083 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
1084 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1085 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]1086 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]1087 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1088</ul>
1089
1090<h3>1.8.2: Dec 21 1999</h3>
1091<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1092 <li>I got another problem with includes and C++, I hope this issue is fixed
1093 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]1094 <li>Added a few tree modification functions: xmlReplaceNode,
1095 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
1096 xmlDocSetRootElement</li>
1097 <li>Tried to improve the HTML output with help from <a
1098 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1099</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1100
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]1101<h3>1.8.1: Dec 18 1999</h3>
1102<ul>
1103 <li>various patches to avoid troubles when using libxml with C++ compilers
1104 the "namespace" keyword and C escaping in include files</li>
1105 <li>a problem in one of the core macros IS_CHAR was corrected</li>
1106 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
1107 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]1108 <li>fixed a posteriori validation (validation after parsing, or by using a
1109 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]1110 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]1111</ul>
1112
1113<h3>1.8.0: Dec 12 1999</h3>
1114<ul>
1115 <li>cleanup, especially memory wise</li>
1116 <li>the parser should be more reliable, especially the HTML one, it should
1117 not crash, whatever the input !</li>
1118 <li>Integrated various patches, especially a speedup improvement for large
1119 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
1120 configure with --with-buffers to enable them.</li>
1121 <li>attribute normalization, oops should have been added long ago !</li>
1122 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
1123 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]1124</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1125
1126<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1127<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1128 <li>Lots of HTML improvement</li>
1129 <li>Fixed some errors when saving both XML and HTML</li>
1130 <li>More examples, the regression tests should now look clean</li>
1131 <li>Fixed a bug with contiguous charref</li>
1132</ul>
1133
1134<h3>1.7.3: Sep 29 1999</h3>
1135<ul>
1136 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1137 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]1138 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1139</ul>
1140
1141<h3>1.7.1: Sep 24 1999</h3>
1142<ul>
1143 <li>The basic type for strings manipulated by libxml has been renamed in
1144 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1145 is that CHAR was conflicting with a predefined type on Windows. However
1146 on non WIN32 environment, compatibility is provided by the way of a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1147 <strong>#define </strong>.</li>
1148 <li>Changed another error : the use of a structure field called errno, and
1149 leading to troubles on platforms where it's a macro</li>
1150</ul>
1151
1152<h3>1.7.0: sep 23 1999</h3>
1153<ul>
1154 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1155 href="html/libxml-nanohttp.html">nanohttp</a> module.</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1156 <li>Added an errno to report errors by another mean than a simple printf
1157 like callback</li>
1158 <li>Finished ID/IDREF support and checking when validation</li>
1159 <li>Serious memory leaks fixed (there is now a <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]1160 href="html/libxml-xmlmemory.html">memory wrapper</a> module)</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1161 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
1162 implementation</li>
1163 <li>Added an HTML parser front-end</li>
1164</ul>
1165
1166<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1167
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1168<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]1169markup-based structured documents. Here is <a name="example">an example XML
1170document</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]1171<pre>&lt;?xml version="1.0"?&gt;
1172&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too"&gt;
1173 &lt;head&gt;
1174 &lt;title&gt;Welcome to Gnome&lt;/title&gt;
1175 &lt;/head&gt;
1176 &lt;chapter&gt;
1177 &lt;title&gt;The Linux adventure&lt;/title&gt;
1178 &lt;p&gt;bla bla bla ...&lt;/p&gt;
1179 &lt;image href="linus.gif"/&gt;
1180 &lt;p&gt;...&lt;/p&gt;
1181 &lt;/chapter&gt;
1182&lt;/EXAMPLE&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1183
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1184<p>The first line specifies that it's an XML document and gives useful
1185information about its encoding. Then the document is a text format whose
1186structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1187to be closed</strong>. XML is pedantic about this. However, if a tag is empty
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1188(no content), a single tag can serve as both the opening and closing tag if
1189it ends with <code>/&gt;</code> rather than with <code>&gt;</code>. Note
1190that, for example, the image tag has no content (just an attribute) and is
1191closed by ending the tag with <code>/&gt;</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1192
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1193<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]1194structured document maintenance (where it follows the steps of SGML) to
1195simple data encoding mechanisms like configuration file formatting (glade),
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1196spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
1197it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1198
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1199<h2><a name="XSLT">XSLT</a></h2>
1200
Daniel Veillard6e6a6cc2001-02-15 15:55:44 +0000[diff] [blame]1201<p>Check <a href="http://xmlsoft.org/XSLT">the separate libxslt page</a></p>
1202
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1203<p><a href="http://www.w3.org/TR/xslt">XSL Transformations</a>, is a
1204language for transforming XML documents into other XML documents (or
1205HTML/textual output).</p>
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1206
1207<p>A separate library called libxslt is being built on top of libxml2. This
1208module "libxslt" can be found in the Gnome CVS base too.</p>
1209
Daniel Veillard383b1472001-01-23 11:39:52 +0000[diff] [blame]1210<p>You can check the <a
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]1211href="http://cvs.gnome.org/lxr/source/libxslt/FEATURES">features</a>
1212supported and the progresses on the <a
Daniel Veillard82687162001-01-22 15:32:01 +0000[diff] [blame]1213href="http://cvs.gnome.org/lxr/source/libxslt/ChangeLog">Changelog</a></p>
1214
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1215<h2><a name="architecture">libxml architecture</a></h2>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1216
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1217<p>Libxml is made of multiple components; some of them are optional, and most
1218of the block interfaces are public. The main components are:</p>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1219<ul>
1220 <li>an Input/Output layer</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1221 <li>FTP and HTTP client layers (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1222 <li>an Internationalization layer managing the encodings support</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1223 <li>a URI module</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1224 <li>the XML parser and its basic SAX interface</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1225 <li>an HTML parser using the same SAX interface (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1226 <li>a SAX tree module to build an in-memory DOM representation</li>
1227 <li>a tree module to manipulate the DOM representation</li>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1228 <li>a validation module using the DOM representation (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1229 <li>an XPath module for global lookup in a DOM representation
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1230 (optional)</li>
1231 <li>a debug module (optional)</li>
Daniel Veillard4540be42000-08-19 16:40:28 +0000[diff] [blame]1232</ul>
1233
1234<p>Graphically this gives the following:</p>
1235
1236<p><img src="libxml.gif" alt="a graphical view of the various"></p>
1237
1238<p></p>
1239
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1240<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1241
1242<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1243returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1244<strong>xmlDoc</strong> structure). This structure contains information such
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1245as the file name, the document type, and a <strong>children</strong> pointer
1246which is the root of the document (or more exactly the first child under the
1247root which is the document). The tree is made of <strong>xmlNode</strong>s,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1248chained in double-linked lists of siblings and with a children&lt;-&gt;parent
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]1249relationship. An xmlNode can also carry properties (a chain of xmlAttr
1250structures). An attribute may have a value which is a list of TEXT or
1251ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1252
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1253<p>Here is an example (erroneous with respect to the XML spec since there
1254should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1255
1256<p><img src="structure.gif" alt=" structure.gif "></p>
1257
1258<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]1259called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1260prints them back as parsed. This is useful for detecting errors both in XML
1261code and in the XML parser itself. It has an option <strong>--debug</strong>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]1262which prints the actual in-memory structure of the document; here is the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1263result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1264<pre>DOCUMENT
1265version=1.0
1266standalone=true
1267 ELEMENT EXAMPLE
1268 ATTRIBUTE prop1
1269 TEXT
1270 content=gnome is great
1271 ATTRIBUTE prop2
1272 ENTITY_REF
1273 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]1274 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1275 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1276 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1277 TEXT
1278 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1279 ELEMENT chapter
1280 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1281 TEXT
1282 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1283 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1284 TEXT
1285 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]1286 ELEMENT image
1287 ATTRIBUTE href
1288 TEXT
1289 content=linus.gif
1290 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]1291 TEXT
1292 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1293
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1294<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1295
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]1296<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1297
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1298<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1299memory. 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]1300loaded using libxml), it's better to use the SAX interface of libxml. SAX is
1301a <strong>callback-based interface</strong> to the parser. Before parsing,
1302the application layer registers a customized set of callbacks which are
1303called by the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1304
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1305<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]1306libxml, see the <a
1307href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
1308documentation</a>.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1309Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1310
1311<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
1312program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1313binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]1314distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]1315testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1316<pre>SAX.setDocumentLocator()
1317SAX.startDocument()
1318SAX.getEntity(amp)
1319SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
1320SAX.characters( , 3)
1321SAX.startElement(head)
1322SAX.characters( , 4)
1323SAX.startElement(title)
1324SAX.characters(Welcome to Gnome, 16)
1325SAX.endElement(title)
1326SAX.characters( , 3)
1327SAX.endElement(head)
1328SAX.characters( , 3)
1329SAX.startElement(chapter)
1330SAX.characters( , 4)
1331SAX.startElement(title)
1332SAX.characters(The Linux adventure, 19)
1333SAX.endElement(title)
1334SAX.characters( , 4)
1335SAX.startElement(p)
1336SAX.characters(bla bla bla ..., 15)
1337SAX.endElement(p)
1338SAX.characters( , 4)
1339SAX.startElement(image, href='linus.gif')
1340SAX.endElement(image)
1341SAX.characters( , 4)
1342SAX.startElement(p)
1343SAX.characters(..., 3)
1344SAX.endElement(p)
1345SAX.characters( , 3)
1346SAX.endElement(chapter)
1347SAX.characters( , 1)
1348SAX.endElement(EXAMPLE)
1349SAX.endDocument()</pre>
1350
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]1351<p>Most of the other interfaces of libxml are based on the DOM tree-building
1352facility, so nearly everything up to the end of this document presupposes the
1353use of the standard DOM tree build. Note that the DOM tree itself is built by
1354a set of registered default callbacks, without internal specific
1355interface.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1356
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1357<h2><a name="Validation">Validation &amp; DTDs</a></h2>
1358
1359<p>Table of Content:</p>
1360<ol>
1361 <li><a href="#General5">General overview</a></li>
1362 <li><a href="#definition">The definition</a></li>
1363 <li><a href="#Simple">Simple rules</a>
1364 <ol>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame^]1365 <li><a href="#reference">How to reference a DTD from a document</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1366 <li><a href="#Declaring">Declaring elements</a></li>
1367 <li><a href="#Declaring1">Declaring attributes</a></li>
1368 </ol>
1369 </li>
1370 <li><a href="#Some">Some examples</a></li>
1371 <li><a href="#validate">How to validate</a></li>
1372 <li><a href="#Other">Other resources</a></li>
1373</ol>
1374
1375<h3><a name="General5">General overview</a></h3>
1376
1377<p>Well what is validation and what is a DTD ?</p>
1378
1379<p>DTD is the acronym for Document Type Definition. This is a description of
1380the content for a familly of XML files. This is part of the XML 1.0
1381specification, and alows to describe and check that a given document instance
1382conforms to a set of rules detailing its structure and content.</p>
1383
1384<p>Validation is the process of checking a document against a DTD (more
1385generally against a set of construction rules).</p>
1386
1387<p>The validation process and building DTDs are the two most difficult parts
1388of the XML life cycle. Briefly a DTD defines all the possibles element to be
1389found within your document, what is the formal shape of your document tree
1390(by defining the allowed content of an element, either text, a regular
1391expression for the allowed list of children, or mixed content i.e. both text
1392and children). The DTD also defines the allowed attributes for all elements
1393and the types of the attributes.</p>
1394
1395<h3><a name="definition1">The definition</a></h3>
1396
1397<p>The <a href="http://www.w3.org/TR/REC-xml">W3C XML Recommendation</a> (<a
1398href="http://www.xml.com/axml/axml.html">Tim Bray's annotated version of
1399Rev1</a>):</p>
1400<ul>
1401 <li><a href="http://www.w3.org/TR/REC-xml#elemdecls">Declaring
1402 elements</a></li>
1403 <li><a href="http://www.w3.org/TR/REC-xml#attdecls">Declaring
1404 attributes</a></li>
1405</ul>
1406
1407<p>(unfortunately) all this is inherited from the SGML world, the syntax is
1408ancient...</p>
1409
1410<h3><a name="Simple1">Simple rules</a></h3>
1411
1412<p>Writing DTD can be done in multiple ways, the rules to build them if you
1413need something fixed or something which can evolve over time can be radically
1414different. Really complex DTD like Docbook ones are flexible but quite harder
1415to design. I will just focuse on DTDs for a formats with a fixed simple
1416structure. It is just a set of basic rules, and definitely not exhaustive nor
1417useable for complex DTD design.</p>
1418
1419<h4><a name="reference1">How to reference a DTD from a document</a>:</h4>
1420
1421<p>Assuming the top element of the document is <code>spec</code> and the dtd
1422is placed in the file <code>mydtd</code> in the subdirectory
1423<code>dtds</code> of the directory from where the document were loaded:</p>
1424
1425<p><code>&lt;!DOCTYPE spec SYSTEM "dtds/mydtd"&gt;</code></p>
1426
1427<p>Notes:</p>
1428<ul>
1429 <li>the system string is actually an URI-Reference (as defined in <a
1430 href="http://www.ietf.org/rfc/rfc2396.txt">RFC 2396</a>) so you can use a
1431 full URL string indicating the location of your DTD on the Web, this is a
1432 really good thing to do if you want others to validate your document</li>
1433 <li>it is also possible to associate a <code>PUBLIC</code> identifier (a
1434 magic string) so that the DTd is looked up in catalogs on the client side
1435 without having to locate it on the web</li>
1436 <li>a dtd contains a set of elements and attributes declarations, but they
1437 don't define what the root of the document should be. This is explicitely
1438 told to the parser/validator as the first element of the
1439 <code>DOCTYPE</code> declaration.</li>
1440</ul>
1441
1442<h4><a name="Declaring2">Declaring elements</a>:</h4>
1443
1444<p>The following declares an element <code>spec</code>:</p>
1445
1446<p><code>&lt;!ELEMENT spec (front, body, back?)&gt;</code></p>
1447
1448<p>it also expresses that the spec element contains one <code>front</code>,
1449one <code>body</code> and one optionnal <code>back</code> children elements
1450in this order. The declaration of one element of the structure and its
1451content are done in a single declaration. Similary the following declares
1452<code>div1</code> elements:</p>
1453
1454<p><code>&lt;!ELEMENT div1 (head, (p | list | note)*, div2*)&gt;</code></p>
1455
1456<p>means div1 contains one <code>head</code> then a series of optional
1457<code>p</code>, <code>list</code>s and <code>note</code>s and then an
1458optional <code>div2</code>. And last but not least an element can contain
1459text:</p>
1460
1461<p><code>&lt;!ELEMENT b (#PCDATA)&gt;</code></p>
1462
1463<p><code>b</code> contains text or being of mixed content (text and elements
1464in no particular order):</p>
1465
1466<p><code>&lt;!ELEMENT p (#PCDATA|a|ul|b|i|em)*&gt;</code></p>
1467
1468<p><code>p </code>can contain text or <code>a</code>, <code>ul</code>,
1469<code>b</code>, <code>i </code>or <code>em</code> elements in no particular
1470order.</p>
1471
1472<h4><a name="Declaring1">Declaring attributes</a>:</h4>
1473
1474<p>again the attributes declaration includes their content definition:</p>
1475
1476<p><code>&lt;!ATTLIST termdef name CDATA #IMPLIED&gt;</code></p>
1477
1478<p>means that the element <code>termdef</code> can have a <code>name</code>
1479attribute containing text (<code>CDATA</code>) and which is optionnal
1480(<code>#IMPLIED</code>). The attribute value can also be defined within a
1481set:</p>
1482
1483<p><code>&lt;!ATTLIST list type (bullets|ordered|glossary)
1484"ordered"&gt;</code></p>
1485
1486<p>means <code>list</code> element have a <code>type</code> attribute with 3
1487allowed values "bullets", "ordered" or "glossary" and which default to
1488"ordered" if the attribute is not explicitely specified.</p>
1489
1490<p>The content type of an attribute can be text (<code>CDATA</code>),
1491anchor/reference/references
1492(<code>ID</code>/<code>IDREF</code>/<code>IDREFS</code>), entity(ies)
1493(<code>ENTITY</code>/<code>ENTITIES</code>) or name(s)
1494(<code>NMTOKEN</code>/<code>NMTOKENS</code>). The following defines that a
1495<code>chapter</code> element can have an optional <code>id</code> attribute
1496of type <code>ID</code>, usable for reference from attribute of type
1497IDREF:</p>
1498
1499<p><code>&lt;!ATTLIST chapter id ID #IMPLIED&gt;</code></p>
1500
1501<p>The last value of an attribute definition can be <code>#REQUIRED
1502</code>meaning that the attribute has to be given, <code>#IMPLIED</code>
1503meaning that it is optional, or the default value (possibly prefixed by
1504<code>#FIXED</code> if it is the only allowed).</p>
1505
1506<p>Notes:</p>
1507<ul>
1508 <li>usually the attributes pertaining to a given element are declared in a
1509 single expression, but it is just a convention adopted by a lot of DTD
1510 writers:
1511 <pre>&lt;!ATTLIST termdef
1512 id ID #REQUIRED
1513 name CDATA #IMPLIED&gt;</pre>
1514 <p>The previous construct defines both <code>id</code> and
1515 <code>name</code> attributes for the element <code>termdef</code></p>
1516 </li>
1517</ul>
1518
1519<h3><a name="Some1">Some examples</a></h3>
1520
1521<p>The directory <code>test/valid/dtds/</code> in the libxml distribution
1522contains some complex DTD examples. The <code>test/valid/dia.xml</code>
1523example shows an XML file where the simple DTD is directly included within
1524the document.</p>
1525
1526<h3><a name="validate1">How to validate</a></h3>
1527
1528<p>The simplest is to use the xmllint program comming with libxml. The
1529<code>--valid</code> option turn on validation of the files given as input,
1530for example the following validates a copy of the first revision of the XML
15311.0 specification:</p>
1532
1533<p><code>xmllint --valid --noout test/valid/REC-xml-19980210.xml</code></p>
1534
1535<p>the -- noout is used to not output the resulting tree.</p>
1536
1537<p>The <code>--dtdvalid dtd</code> allows to validate the document(s) against
1538a given DTD.</p>
1539
1540<p>Libxml exports an API to handle DTDs and validation, check the <a
1541href="http://xmlsoft.org/html/libxml-valid.html">associated
1542description</a>.</p>
1543
1544<h3><a name="Other1">Other resources</a></h3>
1545
1546<p>DTDs are as old as SGML. So there may be a number of examples on-line, I
1547will just list one for now, others pointers welcome:</p>
1548<ul>
1549 <li><a href="http://www.xml101.com:8081/dtd/">XML-101 DTD</a></li>
1550</ul>
1551
1552<p>I suggest looking at the examples found under test/valid/dtd and any of
1553the large number of books available on XML. The dia example in test/valid
1554should be both simple and complete enough to allow you to build your own.</p>
1555
1556<p></p>
1557
1558<h2><a name="Memory">Memory Management</a></h2>
1559
1560<p>Table of Content:</p>
1561<ol>
1562 <li><a href="#General3">General overview</a></li>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame^]1563 <li><a href="#setting">Setting libxml set of memory routines</a></li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1564 <li><a href="#cleanup">Cleaning up after parsing</a></li>
1565 <li><a href="#Debugging">Debugging routines</a></li>
1566 <li><a href="#General4">General memory requirements</a></li>
1567</ol>
1568
1569<h3><a name="General3">General overview</a></h3>
1570
1571<p>The module <code><a
1572href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlmemory.h</a></code>
1573provides the interfaces to the libxml memory system:</p>
1574<ul>
1575 <li>libxml does not use the libc memory allocator directly but xmlFree(),
1576 xmlMalloc() and xmlRealloc()</li>
1577 <li>those routines can be reallocated to a specific set of routine, by
1578 default the libc ones i.e. free(), malloc() and realloc()</li>
1579 <li>the xmlmemory.c module includes a set of debugging routine</li>
1580</ul>
1581
1582<h3><a name="setting">Setting libxml set of memory routines</a></h3>
1583
1584<p>It is sometimes useful to not use the default memory allocator, either for
1585debugging, analysis or to implement a specific behaviour on memory management
1586(like on embedded systems). Two function calls are available to do so:</p>
1587<ul>
1588 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemGet ()</a>
1589 which return the current set of functions in use by the parser</li>
1590 <li><a
1591 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemSetup()</a>
1592 which allow to set up a new set of memory allocation functions</li>
1593</ul>
1594
1595<p>Of course a call to xmlMemSetup() should probably be done before calling
1596any other libxml routines (unless you are sure your allocations routines are
1597compatibles).</p>
1598
1599<h3><a name="cleanup">Cleaning up after parsing</a></h3>
1600
1601<p>Libxml is not stateless, there is a few set of memory structures needing
1602allocation before the parser is fully functionnal (some encoding structures
1603for example). This also mean that once parsing is finished there is a tiny
1604amount of memory (a few hundred bytes) which can be recollected if you don't
1605reuse the parser immediately:</p>
1606<ul>
1607 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlCleanupParser
1608 ()</a>
1609 is a centralized routine to free the parsing states. Note that it won't
1610 deallocate any produced tree if any (use the xmlFreeDoc() and related
1611 routines for this).</li>
1612 <li><a href="http://xmlsoft.org/html/libxml-parser.html">xmlInitParser
1613 ()</a>
1614 is the dual routine allowing to preallocate the parsing state which can
1615 be useful for example to avoid initialization reentrancy problems when
1616 using libxml in multithreaded applications</li>
1617</ul>
1618
1619<p>Generally xmlCleanupParser() is safe, if needed the state will be rebuild
1620at the next invocation of parser routines, but be careful of the consequences
1621in multithreaded applications.</p>
1622
1623<h3><a name="Debugging">Debugging routines</a></h3>
1624
1625<p>When configured using --with-mem-debug flag (off by default), libxml uses
1626a set of memory allocation debugging routineskeeping track of all allocated
1627blocks and the location in the code where the routine was called. A couple of
1628other debugging routines allow to dump the memory allocated infos to a file
1629or call a specific routine when a given block number is allocated:</p>
1630<ul>
1631 <li><a
1632 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMallocLoc()</a>
1633 <a
1634 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlReallocLoc()</a>
1635 and <a
1636 href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemStrdupLoc()</a>
1637 are the memory debugging replacement allocation routines</li>
1638 <li><a href="http://xmlsoft.org/html/libxml-xmlmemory.html">xmlMemoryDump
1639 ()</a>
1640 dumps all the informations about the allocated memory block lefts in the
1641 <code>.memdump</code> file</li>
1642</ul>
1643
1644<p>When developping libxml memory debug is enabled, the tests programs call
1645xmlMemoryDump () and the "make test" regression tests will check for any
1646memory leak during the full regression test sequence, this helps a lot
1647ensuring that libxml does not leak memory and bullet proof memory
1648allocations use (some libc implementations are known to be far too permissive
1649resulting in major portability problems!).</p>
1650
1651<p>If the .memdump reports a leak, it displays the allocation function and
1652also tries to give some informations about the content and structure of the
1653allocated blocks left. This is sufficient in most cases to find the culprit,
1654but not always. Assuming the allocation problem is reproductible, it is
1655possible to find more easilly:</p>
1656<ol>
1657 <li>write down the block number xxxx not allocated</li>
1658 <li>export the environement variable XML_MEM_BREAKPOINT=xxxx</li>
1659 <li>run the program under a debugger and set a breakpoint on
1660 xmlMallocBreakpoint() a specific function called when this precise block
1661 is allocated</li>
1662 <li>when the breakpoint is reached you can then do a fine analysis of the
1663 allocation an step to see the condition resulting in the missing
1664 deallocation.</li>
1665</ol>
1666
1667<p>I used to use a commercial tool to debug libxml memory problems but after
1668noticing that it was not detecting memory leaks that simple mechanism was
1669used and proved extremely efficient until now.</p>
1670
1671<h3><a name="General4">General memory requirements</a></h3>
1672
1673<p>How much libxml memory require ? It's hard to tell in average it depends
1674of a number of things:</p>
1675<ul>
1676 <li>the parser itself should work in a fixed amout of memory, except for
1677 information maintained about the stacks of names and entities locations.
1678 The I/O and encoding handlers will probably account for a few KBytes.
1679 This is true for both the XML and HTML parser (though the HTML parser
1680 need more state).</li>
1681 <li>If you are generating the DOM tree then memory requirements will grow
1682 nearly lineary with the size of the data. In general for a balanced
1683 textual document the internal memory requirement is about 4 times the
1684 size of the UTF8 serialization of this document (exmple the XML-1.0
1685 recommendation is a bit more of 150KBytes and takes 650KBytes of main
1686 memory when parsed). Validation will add a amount of memory required for
1687 maintaining the external Dtd state which should be linear with the
1688 complexity of the content model defined by the Dtd</li>
1689 <li>If you don't care about the advanced features of libxml like
1690 validation, DOM, XPath or XPointer, but really need to work fixed memory
1691 requirements, then the SAX interface should be used.</li>
1692</ul>
1693
1694<p></p>
1695
1696<h2><a name="Encodings">Encodings support</a></h2>
1697
1698<p>Table of Content:</p>
1699<ol>
1700 <li><a href="encoding.html#What">What does internationalization support
1701 mean ?</a></li>
1702 <li><a href="encoding.html#internal">The internal encoding, how and
1703 why</a></li>
1704 <li><a href="encoding.html#implemente">How is it implemented ?</a></li>
1705 <li><a href="encoding.html#Default">Default supported encodings</a></li>
1706 <li><a href="encoding.html#extend">How to extend the existing
1707 support</a></li>
1708</ol>
1709
1710<h3><a name="What">What does internationalization support mean ?</a></h3>
1711
1712<p>XML was designed from the start to allow the support of any character set
1713by using Unicode. Any conformant XML parser has to support the UTF-8 and
1714UTF-16 default encodings which can both express the full unicode ranges. UTF8
1715is a variable length encoding whose greatest point are to resuse the same
1716emcoding for ASCII and to save space for Western encodings, but it is a bit
1717more complex to handle in practice. UTF-16 use 2 bytes per characters (and
1718sometimes combines two pairs), it makes implementation easier, but looks a
1719bit overkill for Western languages encoding. Moreover the XML specification
1720allows document to be encoded in other encodings at the condition that they
1721are clearly labelled as such. For example the following is a wellformed XML
1722document encoded in ISO-8859 1 and using accentuated letter that we French
1723likes for both markup and content:</p>
1724<pre>&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1725&lt;très&gt;là&lt;/très&gt;</pre>
1726
1727<p>Having internationalization support in libxml means the foolowing:</p>
1728<ul>
1729 <li>the document is properly parsed</li>
1730 <li>informations about it's encoding are saved</li>
1731 <li>it can be modified</li>
1732 <li>it can be saved in its original encoding</li>
1733 <li>it can also be saved in another encoding supported by libxml (for
1734 example straight UTF8 or even an ASCII form)</li>
1735</ul>
1736
1737<p>Another very important point is that the whole libxml API, with the
1738exception of a few routines to read with a specific encoding or save to a
1739specific encoding, is completely agnostic about the original encoding of the
1740document.</p>
1741
1742<p>It should be noted too that the HTML parser embedded in libxml now obbey
1743the same rules too, the following document will be (as of 2.2.2) handled in
1744an internationalized fashion by libxml too:</p>
1745<pre>&lt;!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
1746 "http://www.w3.org/TR/REC-html40/loose.dtd"&gt;
1747&lt;html lang="fr"&gt;
1748&lt;head&gt;
1749 &lt;META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"&gt;
1750&lt;/head&gt;
1751&lt;body&gt;
1752&lt;p&gt;W3C crée des standards pour le Web.&lt;/body&gt;
1753&lt;/html&gt;</pre>
1754
1755<h3><a name="internal">The internal encoding, how and why</a></h3>
1756
1757<p>One of the core decision was to force all documents to be converted to a
1758default internal encoding, and that encoding to be UTF-8, here are the
1759rationale for those choices:</p>
1760<ul>
1761 <li>keeping the native encoding in the internal form would force the libxml
1762 users (or the code associated) to be fully aware of the encoding of the
1763 original document, for examples when adding a text node to a document,
1764 the content would have to be provided in the document encoding, i.e. the
1765 client code would have to check it before hand, make sure it's conformant
1766 to the encoding, etc ... Very hard in practice, though in some specific
1767 cases this may make sense.</li>
1768 <li>the second decision was which encoding. From the XML spec only UTF8 and
1769 UTF16 really makes sense as being the two only encodings for which there
1770 is amndatory support. UCS-4 (32 bits fixed size encoding) could be
1771 considered an intelligent choice too since it's a direct Unicode mapping
1772 support. I selected UTF-8 on the basis of efficiency and compatibility
1773 with surrounding software:
1774 <ul>
1775 <li>UTF-8 while a bit more complex to convert from/to (i.e. slightly
1776 more costly to import and export CPU wise) is also far more compact
1777 than UTF-16 (and UCS-4) for a majority of the documents I see it used
1778 for right now (RPM RDF catalogs, advogato data, various configuration
1779 file formats, etc.) and the key point for today's computer
1780 architecture is efficient uses of caches. If one nearly double the
1781 memory requirement to store the same amount of data, this will trash
1782 caches (main memory/external caches/internal caches) and my take is
1783 that this harms the system far more than the CPU requirements needed
1784 for the conversion to UTF-8</li>
1785 <li>Most of libxml version 1 users were using it with straight ASCII
1786 most of the time, doing the conversion with an internal encoding
1787 requiring all their code to be rewritten was a serious show-stopper
1788 for using UTF-16 or UCS-4.</li>
1789 <li>UTF-8 is being used as the de-facto internal encoding standard for
1790 related code like the <a href="http://www.pango.org/">pango</a>
1791 upcoming Gnome text widget, and a lot of Unix code (yep another place
1792 where Unix programmer base takes a different approach from Microsoft
1793 - they are using UTF-16)</li>
1794 </ul>
1795 </li>
1796</ul>
1797
1798<p>What does this mean in practice for the libxml user:</p>
1799<ul>
1800 <li>xmlChar, the libxml data type is a byte, those bytes must be assembled
1801 as UTF-8 valid strings. The proper way to terminate an xmlChar * string
1802 is simply to append 0 byte, as usual.</li>
1803 <li>One just need to make sure that when using chars outside the ASCII set,
1804 the values has been properly converted to UTF-8</li>
1805</ul>
1806
1807<h3><a name="implemente">How is it implemented ?</a></h3>
1808
1809<p>Let's describe how all this works within libxml, basically the I18N
1810(internationalization) support get triggered only during I/O operation, i.e.
1811when reading a document or saving one. Let's look first at the reading
1812sequence:</p>
1813<ol>
1814 <li>when a document is processed, we usually don't know the encoding, a
1815 simple heuristic allows to detect UTF-18 and UCS-4 from whose where the
1816 ASCII range (0-0x7F) maps with ASCII</li>
1817 <li>the xml declaration if available is parsed, including the encoding
1818 declaration. At that point, if the autodetected encoding is different
1819 from the one declared a call to xmlSwitchEncoding() is issued.</li>
1820 <li>If there is no encoding declaration, then the input has to be in either
1821 UTF-8 or UTF-16, if it is not then at some point when processing the
1822 input, the converter/checker of UTF-8 form will raise an encoding error.
1823 You may end-up with a garbled document, or no document at all ! Example:
1824 <pre>~/XML -&gt; ./xmllint err.xml
1825err.xml:1: error: Input is not proper UTF-8, indicate encoding !
1826&lt;très&gt;là&lt;/très&gt;
1827 ^
1828err.xml:1: error: Bytes: 0xE8 0x73 0x3E 0x6C
1829&lt;très&gt;là&lt;/très&gt;
1830 ^</pre>
1831 </li>
1832 <li>xmlSwitchEncoding() does an encoding name lookup, canonalize it, and
1833 then search the default registered encoding converters for that encoding.
1834 If it's not within the default set and iconv() support has been compiled
1835 it, it will ask iconv for such an encoder. If this fails then the parser
1836 will report an error and stops processing:
1837 <pre>~/XML -&gt; ./xmllint err2.xml
1838err2.xml:1: error: Unsupported encoding UnsupportedEnc
1839&lt;?xml version="1.0" encoding="UnsupportedEnc"?&gt;
1840 ^</pre>
1841 </li>
1842 <li>From that point the encoder process progressingly the input (it is
1843 plugged as a front-end to the I/O module) for that entity. It captures
1844 and convert on-the-fly the document to be parsed to UTF-8. The parser
1845 itself just does UTF-8 checking of this input and process it
1846 transparently. The only difference is that the encoding information has
1847 been added to the parsing context (more precisely to the input
1848 corresponding to this entity).</li>
1849 <li>The result (when using DOM) is an internal form completely in UTF-8
1850 with just an encoding information on the document node.</li>
1851</ol>
1852
1853<p>Ok then what's happen when saving the document (assuming you
1854colllected/built an xmlDoc DOM like structure) ? It depends on the function
1855called, xmlSaveFile() will just try to save in the original encoding, while
1856xmlSaveFileTo() and xmlSaveFileEnc() can optionally save to a given
1857encoding:</p>
1858<ol>
1859 <li>if no encoding is given, libxml will look for an encoding value
1860 associated to the document and if it exists will try to save to that
1861 encoding,
1862 <p>otherwise everything is written in the internal form, i.e. UTF-8</p>
1863 </li>
1864 <li>so if an encoding was specified, either at the API level or on the
1865 document, libxml will again canonalize the encoding name, lookup for a
1866 converter in the registered set or through iconv. If not found the
1867 function will return an error code</li>
1868 <li>the converter is placed before the I/O buffer layer, as another kind of
1869 buffer, then libxml will simply push the UTF-8 serialization to through
1870 that buffer, which will then progressively be converted and pushed onto
1871 the I/O layer.</li>
1872 <li>It is possible that the converter code fails on some input, for example
1873 trying to push an UTF-8 encoded chinese character through the UTF-8 to
1874 ISO-8859-1 converter won't work. Since the encoders are progressive they
1875 will just report the error and the number of bytes converted, at that
1876 point libxml will decode the offending character, remove it from the
1877 buffer and replace it with the associated charRef encoding &amp;#123; and
1878 resume the convertion. This guarante that any document will be saved
1879 without losses (except for markup names where this is not legal, this is
1880 a problem in the current version, in pactice avoid using non-ascci
1881 characters for tags or attributes names @@). A special "ascii" encoding
1882 name is used to save documents to a pure ascii form can be used when
1883 portability is really crucial</li>
1884</ol>
1885
1886<p>Here is a few examples based on the same test document:</p>
1887<pre>~/XML -&gt; ./xmllint isolat1
1888&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;
1889&lt;très&gt;là&lt;/très&gt;
1890~/XML -&gt; ./xmllint --encode UTF-8 isolat1
1891&lt;?xml version="1.0" encoding="UTF-8"?&gt;
1892&lt;très&gt;là  &lt;/très&gt;
1893~/XML -&gt; </pre>
1894
1895<p>The same processing is applied (and reuse most of the code) for HTML I18N
1896processing. Looking up and modifying the content encoding is a bit more
1897difficult since it is located in a &lt;meta&gt; tag under the &lt;head&gt;,
1898so a couple of functions htmlGetMetaEncoding() and htmlSetMetaEncoding() have
1899been provided. The parser also attempts to switch encoding on the fly when
1900detecting such a tag on input. Except for that the processing is the same
1901(and again reuses the same code).</p>
1902
1903<h3><a name="Default">Default supported encodings</a></h3>
1904
1905<p>libxml has a set of default converters for the following encodings
1906(located in encoding.c):</p>
1907<ol>
1908 <li>UTF-8 is supported by default (null handlers)</li>
1909 <li>UTF-16, both little and big endian</li>
1910 <li>ISO-Latin-1 (ISO-8859-1) covering most western languages</li>
1911 <li>ASCII, useful mostly for saving</li>
1912 <li>HTML, a specific handler for the conversion of UTF-8 to ASCII with HTML
1913 predefined entities like &amp;copy; for the Copyright sign.</li>
1914</ol>
1915
1916<p>More over when compiled on an Unix platfor with iconv support the full set
1917of encodings supported by iconv can be instantly be used by libxml. On a
1918linux machine with glibc-2.1 the list of supported encodings and aliases fill
19193 full pages, and include UCS-4, the full set of ISO-Latin encodings, and the
1920various Japanese ones.</p>
1921
1922<h4>Encoding aliases</h4>
1923
1924<p>From 2.2.3, libxml has support to register encoding names aliases. The
1925goal is to be able to parse document whose encoding is supported but where
1926the name differs (for example from the default set of names accepted by
1927iconv). The following functions allow to register and handle new aliases for
1928existing encodings. Once registered libxml will automatically lookup the
1929aliases when handling a document:</p>
1930<ul>
1931 <li>int xmlAddEncodingAlias(const char *name, const char *alias);</li>
1932 <li>int xmlDelEncodingAlias(const char *alias);</li>
1933 <li>const char * xmlGetEncodingAlias(const char *alias);</li>
1934 <li>void xmlCleanupEncodingAliases(void);</li>
1935</ul>
1936
1937<h3><a name="extend">How to extend the existing support</a></h3>
1938
1939<p>Well adding support for new encoding, or overriding one of the encoders
1940(assuming it is buggy) should not be hard, just write an input and output
1941conversion routines to/from UTF-8, and register them using
1942xmlNewCharEncodingHandler(name, xxxToUTF8, UTF8Toxxx), and they will be
1943called automatically if the parser(s) encounter such an encoding name
1944(register it uppercase, this will help). The description of the encoders,
1945their arguments and expected return values are described in the encoding.h
1946header.</p>
1947
1948<p>A quick note on the topic of subverting the parser to use a different
1949internal encoding than UTF-8, in some case people will absolutely want to
1950keep the internal encoding different, I think it's still possible (but the
1951encoding must be compliant with ASCII on the same subrange) though I didn't
1952tried it. The key is to override the default conversion routines (by
1953registering null encoders/decoders for your charsets), and bypass the UTF-8
1954checking of the parser by setting the parser context charset
1955(ctxt-&gt;charset) to something different than XML_CHAR_ENCODING_UTF8, but
1956there is no guarantee taht this will work. You may also have some troubles
1957saving back.</p>
1958
1959<p>Basically proper I18N support is important, this requires at least
1960libxml-2.0.0, but a lot of features and corrections are really available only
1961starting 2.2.</p>
1962
1963<h2><a name="IO">I/O Interfaces</a></h2>
1964
1965<p>Table of Content:</p>
1966<ol>
1967 <li><a href="#General1">General overview</a></li>
1968 <li><a href="#basic">The basic buffer type</a></li>
1969 <li><a href="#Input">Input I/O handlers</a></li>
1970 <li><a href="#Output">Output I/O handlers</a></li>
1971 <li><a href="#entities">The entities loader</a></li>
1972 <li><a href="#Example2">Example of customized I/O</a></li>
1973</ol>
1974
1975<h3><a name="General1">General overview</a></h3>
1976
1977<p>The module <code><a
1978href="http://xmlsoft.org/html/libxml-xmlio.html">xmlIO.h</a></code> provides
1979the interfaces to the libxml I/O system. This consists of 4 main parts:</p>
1980<ul>
1981 <li>Entities loader, this is a routine which tries to fetch the entities
1982 (files) based on their PUBLIC and SYSTEM identifiers. The default loader
1983 don't look at the public identifier since libxml do not maintain a
1984 catalog. You can redefine you own entity loader by using
1985 <code>xmlGetExternalEntityLoader()</code> and
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame^]1986 <code>xmlSetExternalEntityLoader()</code>. <a href="#entities">Check the
1987 example</a>.</li>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]1988 <li>Input I/O buffers which are a commodity structure used by the parser(s)
1989 input layer to handle fetching the informations to feed the parser. This
1990 provides buffering and is also a placeholder where the encoding
1991 convertors to UTF8 are piggy-backed.</li>
1992 <li>Output I/O buffers are similar to the Input ones and fulfill similar
1993 task but when generating a serialization from a tree.</li>
1994 <li>A mechanism to register sets of I/O callbacks and associate them with
1995 specific naming schemes like the protocol part of the URIs.
1996 <p>This affect the default I/O operations and allows to use specific I/O
1997 handlers for certain names.</p>
1998 </li>
1999</ul>
2000
2001<p>The general mechanism used when loading http://rpmfind.net/xml.html for
2002example in the HTML parser is the following:</p>
2003<ol>
2004 <li>The default entity loader calls <code>xmlNewInputFromFile()</code> with
2005 the parsing context and the URI string.</li>
2006 <li>the URI string is checked against the existing registered handlers
2007 using their match() callback function, if the HTTP module was compiled
2008 in, it is registered and its match() function will succeeds</li>
2009 <li>the open() function of the handler is called and if successful will
2010 return an I/O Input buffer</li>
2011 <li>the parser will the start reading from this buffer and progressively
2012 fetch information from the resource, calling the read() function of the
2013 handler until the resource is exhausted</li>
2014 <li>if an encoding change is detected it will be installed on the input
2015 buffer, providing buffering and efficient use of the conversion
2016 routines</li>
2017 <li>once the parser has finished, the close() function of the handler is
2018 called once and the Input buffer and associed resources are
2019 deallocated.</li>
2020</ol>
2021
2022<p>The user defined callbacks are checked first to allow overriding of the
2023default libxml I/O routines.</p>
2024
2025<h3><a name="basic">The basic buffer type</a></h3>
2026
2027<p>All the buffer manipulation handling is done using the
2028<code>xmlBuffer</code> type define in <code><a
2029href="http://xmlsoft.org/html/libxml-tree.html">tree.h</a> </code>which is a
2030resizable memory buffer. The buffer allocation strategy can be selected to be
2031either best-fit or use an exponential doubling one (CPU vs. memory use
2032tradeoff). The values are <code>XML_BUFFER_ALLOC_EXACT</code> and
2033<code>XML_BUFFER_ALLOC_DOUBLEIT</code>, and can be set individually or on a
2034system wide basis using <code>xmlBufferSetAllocationScheme()</code>. A number
2035of functions allows to manipulate buffers with names starting with the
2036<code>xmlBuffer...</code> prefix.</p>
2037
2038<h3><a name="Input">Input I/O handlers</a></h3>
2039
2040<p>An Input I/O handler is a simple structure
2041<code>xmlParserInputBuffer</code> containing a context associated to the
2042resource (file descriptor, or pointer to a protocol handler), the read() and
2043close() callbacks to use and an xmlBuffer. And extra xmlBuffer and a charset
2044encoding handler are also present to support charset conversion when
2045needed.</p>
2046
2047<h3><a name="Output">Output I/O handlers</a></h3>
2048
2049<p>An Output handler <code>xmlOutputBuffer</code> is completely similar to an
2050Input one except the callbacks are write() and close().</p>
2051
2052<h3><a name="entities">The entities loader</a></h3>
2053
2054<p>The entity loader resolves requests for new entities and create inputs for
2055the parser. Creating an input from a filename or an URI string is done
2056through the xmlNewInputFromFile() routine. The default entity loader do not
2057handle the PUBLIC identifier associated with an entity (if any). So it just
2058calls xmlNewInputFromFile() with the SYSTEM identifier (which is mandatory in
2059XML).</p>
2060
2061<p>If you want to hook up a catalog mechanism then you simply need to
2062override the default entity loader, here is an example:</p>
2063<pre>#include &lt;libxml/xmlIO.h&gt;
2064
2065xmlExternalEntityLoader defaultLoader = NULL;
2066
2067xmlParserInputPtr
2068xmlMyExternalEntityLoader(const char *URL, const char *ID,
2069 xmlParserCtxtPtr ctxt) {
2070 xmlParserInputPtr ret;
2071 const char *fileID = NULL;
2072 /* lookup for the fileID depending on ID */
2073
2074 ret = xmlNewInputFromFile(ctxt, fileID);
2075 if (ret != NULL)
2076 return(ret);
2077 if (defaultLoader != NULL)
2078 ret = defaultLoader(URL, ID, ctxt);
2079 return(ret);
2080}
2081
2082int main(..) {
2083 ...
2084
2085 /*
2086 * Install our own entity loader
2087 */
2088 defaultLoader = xmlGetExternalEntityLoader();
2089 xmlSetExternalEntityLoader(xmlMyExternalEntityLoader);
2090
2091 ...
2092}</pre>
2093
2094<h3><a name="Example2">Example of customized I/O</a></h3>
2095
2096<p>This example come from <a href="http://xmlsoft.org/messages/0708.html">a
2097real use case</a>, xmlDocDump() closes the FILE * passed by the application
2098and this was a problem. The <a
2099href="http://xmlsoft.org/messages/0711.html">solution</a> was to redefine a
2100new output handler with the closing call deactivated:</p>
2101<ol>
2102 <li>First define a new I/O ouput allocator where the output don't close the
2103 file:
2104 <pre>xmlOutputBufferPtr
2105xmlOutputBufferCreateOwn(FILE *file, xmlCharEncodingHandlerPtr encoder) {
2106    xmlOutputBufferPtr ret;
2107    
2108    if (xmlOutputCallbackInitialized == 0)
2109        xmlRegisterDefaultOutputCallbacks();
2110
2111    if (file == NULL) return(NULL);
2112    ret = xmlAllocOutputBuffer(encoder);
2113    if (ret != NULL) {
2114        ret-&gt;context = file;
2115        ret-&gt;writecallback = xmlFileWrite;
2116        ret-&gt;closecallback = NULL; /* No close callback */
2117    }
2118    return(ret); <br>
2119
2120
2121
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame^]2122
2123
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2124} </pre>
2125 </li>
2126 <li>And then use it to save the document:
2127 <pre>FILE *f;
2128xmlOutputBufferPtr output;
2129xmlDocPtr doc;
2130int res;
2131
2132f = ...
2133doc = ....
2134
2135output = xmlOutputBufferCreateOwn(f, NULL);
2136res = xmlSaveFileTo(output, doc, NULL);
2137 </pre>
2138 </li>
2139</ol>
2140
2141<h2><a name="Catalog">Catalog support</a></h2>
2142
2143<p>Table of Content:</p>
2144<ol>
2145 <li><a href="General2">General overview</a></li>
2146 <li><a href="#definition">The definition</a></li>
2147 <li><a href="#Simple">Using catalogs</a></li>
2148 <li><a href="#Some">Some examples</a></li>
2149 <li><a href="#reference">How to tune catalog usage</a></li>
2150 <li><a href="#validate">How to debug catalog processing</a></li>
2151 <li><a href="#Declaring">How to create and maintain catalogs</a></li>
2152 <li><a href="#implemento">The implementor corner quick review of the
2153 API</a></li>
2154 <li><a href="#Other">Other resources</a></li>
2155</ol>
2156
2157<h3><a name="General2">General overview</a></h3>
2158
2159<p>What is a catalog? Basically it's a lookup mechanism used when an entity
2160(a file or a remote resource) references another entity. The catalog lookup
2161is inserted between the moment the reference is recognized by the software
2162(XML parser, stylesheet processing, or even images referenced for inclusion
2163in a rendering) and the time where loading that resource is actually
2164started.</p>
2165
2166<p>It is basically used for 3 things:</p>
2167<ul>
2168 <li>mapping from "logical" names, the public identifiers and a more
2169 concrete name usable for download (and URI). For example it can associate
2170 the logical name
2171 <p>"-//OASIS//DTD DocBook XML V4.1.2//EN"</p>
2172 <p>of the DocBook 4.1.2 XML DTD with the actual URL where it can be
2173 downloaded</p>
2174 <p>http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd</p>
2175 </li>
2176 <li>remapping from a given URL to another one, like an HTTP indirection
2177 saying that
2178 <p>"http://www.oasis-open.org/committes/tr.xsl"</p>
2179 <p>should really be looked at</p>
2180 <p>"http://www.oasis-open.org/committes/entity/stylesheets/base/tr.xsl"</p>
2181 </li>
2182 <li>providing a local cache mechanism allowing to load the entities
2183 associated to public identifiers or remote resources, this is a really
2184 important feature for any significant deployment of XML or SGML since it
2185 allows to avoid the aleas and delays associated to fetching remote
2186 resources.</li>
2187</ul>
2188
2189<h3><a name="definition">The definitions</a></h3>
2190
2191<p>Libxml, as of 2.4.3 implements 2 kind of catalogs:</p>
2192<ul>
2193 <li>the older SGML catalogs, the official spec is SGML Open Technical
2194 Resolution TR9401:1997, but is better understood by reading <a
2195 href="http://www.jclark.com/sp/catalog.htm">the SP Catalog page</a> from
2196 James Clark. This is relatively old and not the preferred mode of
2197 operation of libxml.</li>
2198 <li><a href="http://www.oasis-open.org/committees/entity/spec.html">XML
2199 Catalogs</a>
2200 is far more flexible, more recent, uses an XML syntax and should scale
2201 quite better. This is the default option of libxml.</li>
2202</ul>
2203
2204<p></p>
2205
2206<h3><a name="Simple">Using catalog</a></h3>
2207
2208<p>In a normal environment libxml will by default check the presence of a
2209catalog in /etc/xml/catalog, and assuming it has been correctly populated,
2210the processing is completely transparent to the document user. To take a
2211concrete example, suppose you are authoring a DocBook document, this one
2212starts with the following DOCTYPE definition:</p>
2213<pre>&lt;?xml version='1.0'?&gt;
2214&lt;!DOCTYPE book PUBLIC "-//Norman Walsh//DTD DocBk XML V3.1.4//EN"
2215 "http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd"&gt;</pre>
2216
2217<p>When validating the document with libxml, the catalog will be
2218automatically consulted to lookup the public identifier "-//Norman Walsh//DTD
2219DocBk XML V3.1.4//EN" and the system identifier
2220"http://nwalsh.com/docbook/xml/3.1.4/db3xml.dtd", and if these entities have
2221been installed on your system and the catalogs actually point to them, libxml
2222will fetch them from the local disk.</p>
2223
2224<p style="font-size: 10pt"><strong>Note</strong>: Really don't use this
2225DOCTYPE example it's a really old version, but is fine as an example.</p>
2226
2227<p>Libxml will check the catalog each time that it is requested to load an
2228entity, this includes DTD, external parsed entities, stylesheets, etc ... If
2229your system is correctly configured all the authoring phase and processing
2230should use only local files, even if your document stays portable because it
2231uses the canonical public and system ID, referencing the remote document.</p>
2232
2233<h3><a name="Some">Some examples:</a></h3>
2234
2235<p>Here is a couple of fragments from XML Catalogs used in libxml early
2236regression tests in <code>test/catalogs</code> :</p>
2237<pre>&lt;?xml version="1.0"?&gt;
2238&lt;!DOCTYPE catalog PUBLIC
2239 "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2240 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2241&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2242 &lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2243 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2244...</pre>
2245
2246<p>This is the beginning of a catalog for DocBook 4.1.2, XML Catalogs are
2247written in XML, there is a specific namespace for catalog elements
2248"urn:oasis:names:tc:entity:xmlns:xml:catalog". The first entry in this
2249catalog is a <code>public</code> mapping it allows to associate a Public
2250Identifier with an URI.</p>
2251<pre>...
2252 &lt;rewriteSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2253 rewritePrefix="file:///usr/share/xml/docbook/"/&gt;
2254...</pre>
2255
2256<p>A <code>rewriteSystem</code> is a very powerful instruction, it says that
2257any URI starting with a given prefix should be looked at another URI
2258constructed by replacing the prefix with an new one. In effect this acts like
2259a cache system for a full area of the Web. In practice it is extremely useful
2260with a file prefix if you have installed a copy of those resources on your
2261local system.</p>
2262<pre>...
2263&lt;delegatePublic publicIdStartString="-//OASIS//DTD XML Catalog //"
2264 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2265&lt;delegatePublic publicIdStartString="-//OASIS//ENTITIES DocBook XML"
2266 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2267&lt;delegatePublic publicIdStartString="-//OASIS//DTD DocBook XML"
2268 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2269&lt;delegateSystem systemIdStartString="http://www.oasis-open.org/docbook/"
2270 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2271&lt;delegateURI uriStartString="http://www.oasis-open.org/docbook/"
2272 catalog="file:///usr/share/xml/docbook.xml"/&gt;
2273...</pre>
2274
2275<p>Delegation is the core features which allows to build a tree of catalogs,
2276easier to maintain than a single catalog, based on Public Identifier, System
2277Identifier or URI prefixes it instructs the catalog software to look up
2278entries in another resource. This feature allow to build hierarchies of
2279catalogs, the set of entries presented should be sufficient to redirect the
2280resolution of all DocBook references to the specific catalog in
2281<code>/usr/share/xml/docbook.xml</code> this one in turn could delegate all
2282references for DocBook 4.2.1 to a specific catalog installed at the same time
2283as the DocBook resources on the local machine.</p>
2284
2285<h3><a name="reference">How to tune catalog usage:</a></h3>
2286
2287<p>The user can change the default catalog behaviour by redirecting queries
2288to its own set of catalogs, this can be done by setting the
2289<code>XML_CATALOG_FILES</code> environment variable to a list of catalogs, an
2290empty one should deactivate loading the default <code>/etc/xml/catalog</code>
2291default catalog</p>
2292
2293<h3><a name="validate">How to debug catalog processing:</a></h3>
2294
2295<p>Setting up the <code>XML_DEBUG_CATALOG</code> environment variable will
2296make libxml output debugging informations for each catalog operations, for
2297example:</p>
2298<pre>orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2299warning: failed to load external entity "title.xml"
2300orchis:~/XML -&gt; export XML_DEBUG_CATALOG=
2301orchis:~/XML -&gt; xmllint --memory --noout test/ent2
2302Failed to parse catalog /etc/xml/catalog
2303Failed to parse catalog /etc/xml/catalog
2304warning: failed to load external entity "title.xml"
2305Catalogs cleanup
2306orchis:~/XML -&gt; </pre>
2307
2308<p>The test/ent2 references an entity, running the parser from memory makes
2309the base URI unavailable and the the "title.xml" entity cannot be loaded.
2310Setting up the debug environment variable allows to detect that an attempt is
2311made to load the <code>/etc/xml/catalog</code> but since it's not present the
2312resolution fails.</p>
2313
2314<p>But the most advanced way to debug XML catalog processing is to use the
2315<strong>xmlcatalog</strong> command shipped with libxml2, it allows to load
2316catalogs and make resolution queries to see what is going on. This is also
2317used for the regression tests:</p>
2318<pre>orchis:~/XML -&gt; ./xmlcatalog test/catalogs/docbook.xml \
2319 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2320http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2321orchis:~/XML -&gt; </pre>
2322
2323<p>For debugging what is going on, adding one -v flags increase the verbosity
2324level to indicate the processing done (adding a second flag also indicate
2325what elements are recognized at parsing):</p>
2326<pre>orchis:~/XML -&gt; ./xmlcatalog -v test/catalogs/docbook.xml \
2327 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2328Parsing catalog test/catalogs/docbook.xml's content
2329Found public match -//OASIS//DTD DocBook XML V4.1.2//EN
2330http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2331Catalogs cleanup
2332orchis:~/XML -&gt; </pre>
2333
2334<p>A shell interface is also available to debug and process multiple queries
2335(and for regression tests):</p>
2336<pre>orchis:~/XML -&gt; ./xmlcatalog -shell test/catalogs/docbook.xml \
2337 "-//OASIS//DTD DocBook XML V4.1.2//EN"
2338&gt; help
2339Commands available:
2340public PublicID: make a PUBLIC identifier lookup
2341system SystemID: make a SYSTEM identifier lookup
2342resolve PublicID SystemID: do a full resolver lookup
2343add 'type' 'orig' 'replace' : add an entry
2344del 'values' : remove values
2345dump: print the current catalog state
2346debug: increase the verbosity level
2347quiet: decrease the verbosity level
2348exit: quit the shell
2349&gt; public "-//OASIS//DTD DocBook XML V4.1.2//EN"
2350http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd
2351&gt; quit
2352orchis:~/XML -&gt; </pre>
2353
2354<p>This should be sufficient for most debugging purpose, this was actually
2355used heavily to debug the XML Catalog implementation itself.</p>
2356
2357<h3><a name="Declaring">How to create and maintain</a> catalogs:</h3>
2358
2359<p>Basically XML Catalogs are XML files, you can either use XML tools to
2360manage them or use <strong>xmlcatalog</strong> for this. The basic step is
2361to create a catalog the -create option provide this facility:</p>
2362<pre>orchis:~/XML -&gt; ./xmlcatalog --create tst.xml
2363&lt;?xml version="1.0"?&gt;
2364&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2365 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2366&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2367orchis:~/XML -&gt; </pre>
2368
2369<p>By default xmlcatalog does not overwrite the original catalog and save the
2370result on the standard output, this can be overridden using the -noout
2371option. The <code>-add</code> command allows to add entries in the
2372catalog:</p>
2373<pre>orchis:~/XML -&gt; ./xmlcatalog --noout --create --add "public" \
2374 "-//OASIS//DTD DocBook XML V4.1.2//EN" \
2375 http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd tst.xml
2376orchis:~/XML -&gt; cat tst.xml
2377&lt;?xml version="1.0"?&gt;
2378&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN" \
2379 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2380&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"&gt;
2381&lt;public publicId="-//OASIS//DTD DocBook XML V4.1.2//EN"
2382 uri="http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd"/&gt;
2383&lt;/catalog&gt;
2384orchis:~/XML -&gt; </pre>
2385
2386<p>The <code>-add</code> option will always take 3 parameters even if some of
2387the XML Catalog constructs (like nextCatalog) will have only a single
2388argument, just pass a third empty string, it will be ignored.</p>
2389
2390<p>Similarly the <code>-del</code> option remove matching entries from the
2391catalog:</p>
2392<pre>orchis:~/XML -&gt; ./xmlcatalog --del \
2393 "http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" tst.xml
2394&lt;?xml version="1.0"?&gt;
2395&lt;!DOCTYPE catalog PUBLIC "-//OASIS//DTD Entity Resolution XML Catalog V1.0//EN"
2396 "http://www.oasis-open.org/committees/entity/release/1.0/catalog.dtd"&gt;
2397&lt;catalog xmlns="urn:oasis:names:tc:entity:xmlns:xml:catalog"/&gt;
2398orchis:~/XML -&gt; </pre>
2399
2400<p>The catalog is now empty. Note that the matching of <code>-del</code> is
2401exact and would have worked in a similar fashion with the Public ID
2402string.</p>
2403
2404<p>This is rudimentary but should be sufficient to manage a not too complex
2405catalog tree of resources.</p>
2406
2407<h3><a name="implemento">The implementor corner quick review of the
2408API:</a></h3>
2409
2410<p>First, and like for every other module of libxml, there is an
2411automatically generated <a href="html/libxml-catalog.html">API page for
2412catalog support</a>.</p>
2413
2414<p>The header for the catalog interfaces should be included as:</p>
2415<pre>#include &lt;libxml/catalog.h&gt;</pre>
2416
2417<p>The API is voluntarily kept very simple. First it is not obvious that
2418applications really need access to it since it is the default behaviour of
2419libxml (Note: it is possible to completely override libxml default catalog by
2420using <a href="html/libxml-parser.html">xmlSetExternalEntityLoader</a> to
2421plug an application specific resolver).</p>
2422
2423<p>Basically libxml support 2 catalog lists:</p>
2424<ul>
2425 <li>the default one, global shared by all the application</li>
2426 <li>a per-document catalog, this one is built if the document uses the
2427 <code>oasis-xml-catalog</code> PIs to specify its own catalog list, it is
2428 associated to the parser context and destroyed when the parsing context
2429 is destroyed.</li>
2430</ul>
2431
2432<p>the document one will be used first if it exists.</p>
2433
2434<h4>Initialization routines:</h4>
2435
2436<p>xmlInitializeCatalog(), xmlLoadCatalog() and xmlLoadCatalogs() should be
2437used at startup to initialize the catalog, if the catalog should be
2438initialized with specific values xmlLoadCatalog() or xmlLoadCatalogs()
2439should be called before xmlInitializeCatalog() which would otherwise do a
2440default initialization first.</p>
2441
2442<p>The xmlCatalogAddLocal() call is used by the parser to grow the document
2443own catalog list if needed.</p>
2444
2445<h4>Preferences setup:</h4>
2446
2447<p>The XML Catalog spec requires the possibility to select default
2448preferences between public and system delegation,
2449xmlCatalogSetDefaultPrefer() allows this, xmlCatalogSetDefaults() and
2450xmlCatalogGetDefaults() allow to control if XML Catalogs resolution should
2451be forbidden, allowed for global catalog, for document catalog or both, the
2452default is to allow both.</p>
2453
2454<p>And of course xmlCatalogSetDebug() allows to generate debug messages
2455(through the xmlGenericError() mechanism).</p>
2456
2457<h4>Querying routines:</h4>
2458
2459<p>xmlCatalogResolve(), xmlCatalogResolveSystem(), xmlCatalogResolvePublic()
2460and xmlCatalogResolveURI() are relatively explicit if you read the XML
2461Catalog specification they correspond to section 7 algorithms, they should
2462also work if you have loaded an SGML catalog with a simplified semantic.</p>
2463
2464<p>xmlCatalogLocalResolve() and xmlCatalogLocalResolveURI() are the same but
2465operate on the document catalog list</p>
2466
2467<h4>Cleanup and Miscellaneous:</h4>
2468
2469<p>xmlCatalogCleanup() free-up the global catalog, xmlCatalogFreeLocal() is
2470the per-document equivalent.</p>
2471
2472<p>xmlCatalogAdd() and xmlCatalogRemove() are used to dynamically modify the
2473first catalog in the global list, and xmlCatalogDump() allows to dump a
2474catalog state, those routines are primarily designed for xmlcatalog, I'm not
2475sure that exposing more complex interfaces (like navigation ones) would be
2476really useful.</p>
2477
2478<p>The xmlParseCatalogFile() is a function used to load XML Catalog files,
2479it's similar as xmlParseFile() except it bypass all catalog lookups, it's
2480provided because this functionality may be useful for client tools.</p>
2481
2482<h4>threaded environments:</h4>
2483
2484<p>Since the catalog tree is built progressively, some care has been taken to
2485try to avoid troubles in multithreaded environments. The code is now thread
2486safe assuming that the libxml library has been compiled with threads
2487support.</p>
2488
2489<p></p>
2490
2491<h3><a name="Other">Other resources</a></h3>
2492
2493<p>The XML Catalog specification is relatively recent so there isn't much
2494literature to point at:</p>
2495<ul>
2496 <li>You can find an good rant from Norm Walsh about <a
2497 href="http://www.arbortext.com/Think_Tank/XML_Resources/Issue_Three/issue_three.html">the
2498 need for catalogs</a>, it provides a lot of context informations even if
2499 I don't agree with everything presented.</li>
2500 <li>An <a href="http://home.ccil.org/~cowan/XML/XCatalog.html">old XML
2501 catalog proposal</a> from John Cowan</li>
2502 <li>The <a href="http://www.rddl.org/">Resource Directory Description
2503 Language</a> (RDDL) another catalog system but more oriented toward
2504 providing metadata for XML namespaces.</li>
2505 <li>the page from the OASIS Technical <a
2506 href="http://www.oasis-open.org/committees/entity/">Committee on Entity
2507 Resolution</a> who maintains XML Catalog, you will find pointers to the
2508 specification update, some background and pointers to others tools
2509 providing XML Catalog support</li>
2510 <li>I have uploaded <a href="ftp://xmlsoft.org/test/dbk412catalog.tar.gz">a
2511 mall tarball</a> containing XML Catalogs for DocBook 4.1.2 which seems to
2512 work fine for me</li>
2513 <li>The <a href="http://www.xmlsoft.org/xmlcatalog_man.html">xmlcatalog
2514 manual page</a></li>
2515</ul>
2516
2517<p>If you have suggestions for corrections or additions, simply contact
2518me:</p>
2519
2520<h2><a name="library">The parser interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2521
2522<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2523using the XML library from the C language. It is not intended to be
2524extensive. I hope the automatically generated documents will provide the
2525completeness required, but as a separate set of documents. The interfaces of
2526the XML library are by principle low level, there is nearly zero abstraction.
2527Those interested in a higher level API should <a href="#DOM">look at
2528DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2529
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2530<p>The <a href="html/libxml-parser.html">parser interfaces for XML</a> are
2531separated from the <a href="html/libxml-htmlparser.html">HTML parser
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2532interfaces</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]2533
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2534<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2535
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2536<p>Usually, the first thing to do is to read an XML input. The parser accepts
2537documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2538defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2539<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2540 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2541 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2542 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2543</dl>
2544<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2545 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2546 <dd><p>Parse an XML document contained in a (possibly compressed)
2547 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2548 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2549</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2550
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2551<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]2552failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2553
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2554<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2555
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2556<p>In order for the application to keep the control when the document is
2557being fetched (which is common for GUI based programs) libxml provides a push
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2558interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2559<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
2560 void *user_data,
2561 const char *chunk,
2562 int size,
2563 const char *filename);
2564int xmlParseChunk (xmlParserCtxtPtr ctxt,
2565 const char *chunk,
2566 int size,
2567 int terminate);</pre>
2568
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2569<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2570<pre> FILE *f;
2571
2572 f = fopen(filename, "r");
2573 if (f != NULL) {
2574 int res, size = 1024;
2575 char chars[1024];
2576 xmlParserCtxtPtr ctxt;
2577
2578 res = fread(chars, 1, 4, f);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2579 if (res &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2580 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
2581 chars, res, filename);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2582 while ((res = fread(chars, 1, size, f)) &gt; 0) {
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2583 xmlParseChunk(ctxt, chars, res, 0);
2584 }
2585 xmlParseChunk(ctxt, chars, 0, 1);
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2586 doc = ctxt-&gt;myDoc;
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2587 xmlFreeParserCtxt(ctxt);
2588 }
2589 }</pre>
2590
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2591<p>The HTML parser embedded into libxml also has a push interface; the
2592functions are just prefixed by "html" rather than "xml".</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2593
2594<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
2595
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2596<p>The tree-building interface makes the parser memory-hungry, first loading
2597the document in memory and then building the tree itself. Reading a document
2598without building the tree is possible using the SAX interfaces (see SAX.h and
2599<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]2600Henstridge's documentation</a>). Note also that the push interface can be
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2601limited to SAX: just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2602<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]2603
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2604<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2605
2606<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]2607there is a set of functions dedicated to building new elements. (These are
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2608also described in &lt;libxml/tree.h&gt;.) For example, here is a piece of
2609code that produces the XML document used in the previous examples:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2610<pre> #include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]2611 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2612 xmlNodePtr tree, subtree;
2613
2614 doc = xmlNewDoc("1.0");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2615 doc-&gt;children = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
2616 xmlSetProp(doc-&gt;children, "prop1", "gnome is great");
2617 xmlSetProp(doc-&gt;children, "prop2", "&amp; linux too");
2618 tree = xmlNewChild(doc-&gt;children, NULL, "head", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2619 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2620 tree = xmlNewChild(doc-&gt;children, NULL, "chapter", NULL);
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2621 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
2622 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
2623 subtree = xmlNewChild(tree, NULL, "image", NULL);
2624 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2625
2626<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2627
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2628<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2629
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2630<p>Basically by <a href="html/libxml-tree.html">including "tree.h"</a> your
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2631code has access to the internal structure of all the elements of the tree.
2632The names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard306be992000-07-03 12:38:45 +0000[diff] [blame]2633<strong>children</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2634<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]2635example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2636<pre><code>doc-&gt;children-&gt;children-&gt;children</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2637
2638<p>points to the title element,</p>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2639<pre>doc-&gt;children-&gt;children-&gt;next-&gt;children-&gt;children</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2640
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2641<p>points to the text node containing the chapter title "The Linux
2642adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2643
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2644<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]2645present before the document root, so <code>doc-&gt;children</code> may point
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2646to an element which is not the document Root Element; a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]2647<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]2648
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2649<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2650
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2651<p>Functions are provided for reading and writing the document content. Here
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2652is an excerpt from the <a href="html/libxml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2653<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2654 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
2655 xmlChar *value);</code></dt>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2656 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node.
2657 The value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2658 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2659</dl>
2660<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2661 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2662 *name);</code></dt>
Daniel Veillardc92c3042000-09-29 02:42:04 +0000[diff] [blame]2663 <dd><p>This function returns a pointer to new copy of the property
2664 content. Note that the user must deallocate the result.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2665 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2666</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2667
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2668<p>Two functions are provided for reading and writing the text associated
2669with elements:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2670<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2671 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2672 *value);</code></dt>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2673 <dd><p>This function takes an "external" string and converts it to one
2674 text node or possibly to a list of entity and text nodes. All
2675 non-predefined entity references like &amp;Gnome; will be stored
2676 internally as entity nodes, hence the result of the function may not be
2677 a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2678 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2679</dl>
2680<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2681 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2682 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2683 <dd><p>This function is the inverse of
2684 <code>xmlStringGetNodeList()</code>. It generates a new string
2685 containing the content of the text and entity nodes. Note the extra
2686 argument inLine. If this argument is set to 1, the function will expand
2687 entity references. For example, instead of returning the &amp;Gnome;
2688 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2689 "GNU Network Object Model Environment").</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2690 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2691</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2692
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2693<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2694
2695<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2696<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]2697 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2698 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2699 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2700 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2701</dl>
2702<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2703 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2704 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2705 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2706</dl>
2707<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2708 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2709 <dd><p>Saves the document to a file. In this case, the compression
2710 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2711 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2712</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]2713
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2714<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2715
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2716<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2717accesses. The level of compression on saves can be turned on either globally
2718or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2719<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2720 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2721 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2722 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2723</dl>
2724<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2725 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2726 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2727 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2728</dl>
2729<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2730 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2731 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2732 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2733</dl>
2734<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2735 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2736 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2737 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]2738</dl>
2739
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2740<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2741
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2742<p>Entities in principle are similar to simple C macros. An entity defines an
2743abbreviation for a given string that you can reuse many times throughout the
2744content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2745may occur frequently within a document, or to confine the change needed to a
2746document to a restricted area in the internal subset of the document (at the
2747beginning). Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2748<pre>1 &lt;?xml version="1.0"?&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27492 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27503 &lt;!ENTITY xml "Extensible Markup Language"&gt;
27514 ]&gt;
27525 &lt;EXAMPLE&gt;
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]27536 &amp;xml;
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]27547 &lt;/EXAMPLE&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2755
2756<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]2757its name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2758are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2759predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2760<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2761for the character '&gt;', <strong>&amp;apos;</strong> for the character ''',
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2762<strong>&amp;quot;</strong> for the character '"', and
2763<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2764
2765<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]2766substitute an entity's content so that you can see the replacement text in
2767your application. Or you may prefer to keep entity references as such in the
2768content to be able to save the document back without losing this usually
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2769precious information (if the user went through the pain of explicitly
2770defining entities, he may have a a rather negative attitude if you blindly
2771susbtitute them as saving time). The <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]2772href="html/libxml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2773function allows you to check and change the behaviour, which is to not
2774substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2775
2776<p>Here is the DOM tree built by libxml for the previous document in the
2777default case:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2778<pre>/gnome/src/gnome-xml -&gt; ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2779DOCUMENT
2780version=1.0
2781 ELEMENT EXAMPLE
2782 TEXT
2783 content=
2784 ENTITY_REF
2785 INTERNAL_GENERAL_ENTITY xml
2786 content=Extensible Markup Language
2787 TEXT
2788 content=</pre>
2789
2790<p>And here is the result when substituting entities:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2791<pre>/gnome/src/gnome-xml -&gt; ./tester --debug --noent test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2792DOCUMENT
2793version=1.0
2794 ELEMENT EXAMPLE
2795 TEXT
2796 content= Extensible Markup Language</pre>
2797
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2798<p>So, entities or no entities? Basically, it depends on your use case. I
2799suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2800entities in your XML document or data if you are not willing to handle the
2801entity references elements in the DOM tree.</p>
2802
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2803<p>Note that at save time libxml enforces the conversion of the predefined
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2804entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2805transparently replace those with chars (i.e. it will not generate entity
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2806reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2807finding them in the input).</p>
2808
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2809<p><span style="background-color: #FF0000">WARNING</span>: handling entities
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2810on top of the libxml SAX interface is difficult!!! If you plan to use
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2811non-predefined entities in your documents, then the learning cuvre to handle
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2812then 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]2813strongly suggest you consider using the DOM interface instead and let libxml
Daniel Veillard8c6d6af2000-08-25 17:14:13 +0000[diff] [blame]2814deal with the complexity rather than trying to do it yourself.</p>
Daniel Veillard7b9c4b72000-08-25 16:26:50 +0000[diff] [blame]2815
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]2816<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2817
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2818<p>The libxml library implements <a
2819href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
2820recognizing namespace contructs in the input, and does namespace lookup
2821automatically when building the DOM tree. A namespace declaration is
2822associated with an in-memory structure and all elements or attributes within
2823that namespace point to it. Hence testing the namespace is a simple and fast
2824equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2825
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2826<p>I suggest that people using libxml use a namespace, and declare it in the
2827root element of their document as the default namespace. Then they don't need
2828to 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]2829refinement and merging of data from different sources. This doesn't increase
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2830the size of the XML output significantly, but significantly increases its
2831value in the long-term. Example:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2832<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/"&gt;
2833 &lt;elem1&gt;...&lt;/elem1&gt;
2834 &lt;elem2&gt;...&lt;/elem2&gt;
2835&lt;/mydoc&gt;</pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2836
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]2837<p>The namespace value has to be an absolute URL, but the URL doesn't have to
2838point to any existing resource on the Web. It will bind all the element and
2839atributes with that URL. I suggest to use an URL within a domain you control,
2840and that the URL should contain some kind of version information if possible.
2841For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is a good
2842namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2843
2844<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]2845version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2846and if the version information don't match something you know, warn the user
2847and 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]2848namespace checking on the prefix value. &lt;foo:text&gt; may be exactly the
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2849same as &lt;bar:text&gt; in another document. What really matters is the URI
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]2850associated with the element or the attribute, not the prefix string (which is
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2851just a shortcut for the full URI). In libxml, element and attributes have an
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]2852<code>ns</code> field pointing to an xmlNs structure detailing the namespace
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2853prefix and its URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2854
2855<p>@@Interfaces@@</p>
2856
2857<p>@@Examples@@</p>
2858
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2859<p>Usually people object to using namespaces together with validity checking.
2860I will try to make sure that using namespaces won't break validity checking,
2861so even if you plan to use or currently are using validation I strongly
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]2862suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2863<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]2864flexible parsers. Using namespaces to mix and differentiate content coming
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2865from multiple DTDs will certainly break current validation schemes. I will
2866try to provide ways to do this, but this may not be portable or
2867standardized.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2868
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2869<h2><a name="Upgrading">Upgrading 1.x code</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2870
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2871<p>Incompatible changes:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2872
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2873<p>Version 2 of libxml is the first version introducing serious backward
2874incompatible changes. The main goals were:</p>
2875<ul>
2876 <li>a general cleanup. A number of mistakes inherited from the very early
2877 versions couldn't be changed due to compatibility constraints. Example
2878 the "childs" element in the nodes.</li>
2879 <li>Uniformization of the various nodes, at least for their header and link
2880 parts (doc, parent, children, prev, next), the goal is a simpler
2881 programming model and simplifying the task of the DOM implementors.</li>
2882 <li>better conformances to the XML specification, for example version 1.x
2883 had an heuristic to try to detect ignorable white spaces. As a result the
2884 SAX event generated were ignorableWhitespace() while the spec requires
2885 character() in that case. This also mean that a number of DOM node
2886 containing blank text may populate the DOM tree which were not present
2887 before.</li>
2888</ul>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2889
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2890<h3>How to fix libxml-1.x code:</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2891
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2892<p>So client code of libxml designed to run with version 1.x may have to be
2893changed to compile against version 2.x of libxml. Here is a list of changes
2894that I have collected, they may not be sufficient, so in case you find other
2895change which are required, <a href="mailto:Daniel.Ïeillardw3.org">drop me a
2896mail</a>:</p>
2897<ol>
2898 <li>The package name have changed from libxml to libxml2, the library name
2899 is now -lxml2 . There is a new xml2-config script which should be used to
2900 select the right parameters libxml2</li>
2901 <li>Node <strong>childs</strong> field has been renamed
2902 <strong>children</strong> so s/childs/children/g should be applied
2903 (probablility of having "childs" anywere else is close to 0+</li>
2904 <li>The document don't have anymore a <strong>root</strong> element it has
2905 been replaced by <strong>children</strong> and usually you will get a
2906 list of element here. For example a Dtd element for the internal subset
2907 and it's declaration may be found in that list, as well as processing
2908 instructions or comments found before or after the document root element.
2909 Use <strong>xmlDocGetRootElement(doc)</strong> to get the root element of
2910 a document. Alternatively if you are sure to not reference Dtds nor have
2911 PIs or comments before or after the root element
2912 s/-&gt;root/-&gt;children/g will probably do it.</li>
2913 <li>The white space issue, this one is more complex, unless special case of
2914 validating parsing, the line breaks and spaces usually used for indenting
2915 and formatting the document content becomes significant. So they are
2916 reported by SAX and if your using the DOM tree, corresponding nodes are
2917 generated. Too approach can be taken:
2918 <ol>
2919 <li>lazy one, use the compatibility call
2920 <strong>xmlKeepBlanksDefault(0)</strong> but be aware that you are
2921 relying on a special (and possibly broken) set of heuristics of
2922 libxml to detect ignorable blanks. Don't complain if it breaks or
2923 make your application not 100% clean w.r.t. to it's input.</li>
2924 <li>the Right Way: change you code to accept possibly unsignificant
2925 blanks characters, or have your tree populated with weird blank text
2926 nodes. You can spot them using the comodity function
2927 <strong>xmlIsBlankNode(node)</strong> returning 1 for such blank
2928 nodes.</li>
2929 </ol>
2930 <p>Note also that with the new default the output functions don't add any
2931 extra indentation when saving a tree in order to be able to round trip
2932 (read and save) without inflating the document with extra formatting
2933 chars.</p>
2934 </li>
2935 <li>The include path has changed to $prefix/libxml/ and the includes
2936 themselves uses this new prefix in includes instructions... If you are
2937 using (as expected) the
2938 <pre>xml2-config --cflags</pre>
2939 <p>output to generate you compile commands this will probably work out of
2940 the box</p>
2941 </li>
2942 <li>xmlDetectCharEncoding takes an extra argument indicating the lenght in
2943 byte of the head of the document available for character detection.</li>
2944</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2945
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2946<h3>Ensuring both libxml-1.x and libxml-2.x compatibility</h3>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2947
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2948<p>Two new version of libxml (1.8.11) and libxml2 (2.3.4) have been released
2949to allow smoth upgrade of existing libxml v1code while retaining
2950compatibility. They offers the following:</p>
2951<ol>
2952 <li>similar include naming, one should use
2953 <strong>#include&lt;libxml/...&gt;</strong> in both cases.</li>
2954 <li>similar identifiers defined via macros for the child and root fields:
2955 respectively <strong>xmlChildrenNode</strong> and
2956 <strong>xmlRootNode</strong></li>
2957 <li>a new macro <strong>LIBXML_TEST_VERSION</strong> which should be
2958 inserted once in the client code</li>
2959</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2960
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2961<p>So the roadmap to upgrade your existing libxml applications is the
2962following:</p>
2963<ol>
2964 <li>install the libxml-1.8.8 (and libxml-devel-1.8.8) packages</li>
2965 <li>find all occurences where the xmlDoc <strong>root</strong> field is
2966 used and change it to <strong>xmlRootNode</strong></li>
2967 <li>similary find all occurences where the xmlNode <strong>childs</strong>
2968 field is used and change it to <strong>xmlChildrenNode</strong></li>
2969 <li>add a <strong>LIBXML_TEST_VERSION</strong> macro somewhere in your
2970 <strong>main()</strong> or in the library init entry point</li>
2971 <li>Recompile, check compatibility, it should still work</li>
2972 <li>Change your configure script to look first for xml2-config and fallback
2973 using xml-config . Use the --cflags and --libs ouptut of the command as
2974 the Include and Linking parameters needed to use libxml.</li>
2975 <li>install libxml2-2.3.x and libxml2-devel-2.3.x (libxml-1.8.y and
2976 libxml-devel-1.8.y can be kept simultaneously)</li>
2977 <li>remove your config.cache, relaunch your configuration mechanism, and
2978 recompile, if steps 2 and 3 were done right it should compile as-is</li>
2979 <li>Test that your application is still running correctly, if not this may
2980 be due to extra empty nodes due to formating spaces being kept in libxml2
2981 contrary to libxml1, in that case insert xmlKeepBlanksDefault(1) in your
2982 code before calling the parser (next to
2983 <strong>LIBXML_TEST_VERSION</strong> is a fine place).</li>
2984</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2985
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2986<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]2987
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]2988<p>Let me put some emphasis on the fact that there is far more changes from
2989libxml 1.x to 2.x than the ones you may have to patch for. The overall code
2990has been considerably cleaned up and the conformance to the XML specification
2991has been drastically improved too. Don't take those changes as an excuse to
2992not upgrade, it may cost a lot on the long term ...</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]2993
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]2994<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2995
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]2996<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document
2997Object Model</em>; this is an API for accessing XML or HTML structured
2998documents. Native support for DOM in Gnome is on the way (module gnome-dom),
2999and will be based on gnome-xml. This will be a far cleaner interface to
3000manipulate XML files within Gnome since it won't expose the internal
3001structure.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3002
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3003<p>The current DOM implementation on top of libxml is the <a
Daniel Veillarda47fb3d2001-03-25 17:23:49 +0000[diff] [blame]3004href="http://cvs.gnome.org/lxr/source/gdome2/">gdome2 Gnome module</a>, this
3005is a full DOM interface, thanks to Paolo Casarini, check the <a
3006href="http://www.cs.unibo.it/~casarini/gdome2/">Gdome2 homepage</a> for more
3007informations.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3008
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]3009<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3010
3011<p>Here is a real size example, where the actual content of the application
3012data 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]3013a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3014storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
3015base</a>:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3016<pre>&lt;?xml version="1.0"?&gt;
3017&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"&gt;
3018 &lt;gjob:Jobs&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3019
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3020 &lt;gjob:Job&gt;
3021 &lt;gjob:Project ID="3"/&gt;
3022 &lt;gjob:Application&gt;GBackup&lt;/gjob:Application&gt;
3023 &lt;gjob:Category&gt;Development&lt;/gjob:Category&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3024
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3025 &lt;gjob:Update&gt;
3026 &lt;gjob:Status&gt;Open&lt;/gjob:Status&gt;
3027 &lt;gjob:Modified&gt;Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified&gt;
3028 &lt;gjob:Salary&gt;USD 0.00&lt;/gjob:Salary&gt;
3029 &lt;/gjob:Update&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3030
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3031 &lt;gjob:Developers&gt;
3032 &lt;gjob:Developer&gt;
3033 &lt;/gjob:Developer&gt;
3034 &lt;/gjob:Developers&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3035
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3036 &lt;gjob:Contact&gt;
3037 &lt;gjob:Person&gt;Nathan Clemons&lt;/gjob:Person&gt;
3038 &lt;gjob:Email&gt;nathan@windsofstorm.net&lt;/gjob:Email&gt;
3039 &lt;gjob:Company&gt;
3040 &lt;/gjob:Company&gt;
3041 &lt;gjob:Organisation&gt;
3042 &lt;/gjob:Organisation&gt;
3043 &lt;gjob:Webpage&gt;
3044 &lt;/gjob:Webpage&gt;
3045 &lt;gjob:Snailmail&gt;
3046 &lt;/gjob:Snailmail&gt;
3047 &lt;gjob:Phone&gt;
3048 &lt;/gjob:Phone&gt;
3049 &lt;/gjob:Contact&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3050
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3051 &lt;gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3052 The program should be released as free software, under the GPL.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3053 &lt;/gjob:Requirements&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3054
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3055 &lt;gjob:Skills&gt;
3056 &lt;/gjob:Skills&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:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3059 A GNOME based system that will allow a superuser to configure
3060 compressed and uncompressed files and/or file systems to be backed
3061 up with a supported media in the system. This should be able to
3062 perform via find commands generating a list of files that are passed
3063 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
3064 or via operations performed on the filesystem itself. Email
3065 notification and GUI status display very important.
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3066 &lt;/gjob:Details&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3067
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3068 &lt;/gjob:Job&gt;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3069
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3070 &lt;/gjob:Jobs&gt;
3071&lt;/gjob:Helping&gt;</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3072
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3073<p>While loading the XML file into an internal DOM tree is a matter of
3074calling only a couple of functions, browsing the tree to gather the ata and
3075generate the internal structures is harder, and more error prone.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3076
3077<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3078structure. For example, the ordering of the attributes is not significant,
3079the 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]3080depend on the order of the children of a given node, unless it really makes
3081things harder. Here is some code to parse the information for a person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3082<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3083 * A person record
3084 */
3085typedef struct person {
3086 char *name;
3087 char *email;
3088 char *company;
3089 char *organisation;
3090 char *smail;
3091 char *webPage;
3092 char *phone;
3093} person, *personPtr;
3094
3095/*
3096 * And the code needed to parse it
3097 */
3098personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3099 personPtr ret = NULL;
3100
3101DEBUG("parsePerson\n");
3102 /*
3103 * allocate the struct
3104 */
3105 ret = (personPtr) malloc(sizeof(person));
3106 if (ret == NULL) {
3107 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3108 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3109 }
3110 memset(ret, 0, sizeof(person));
3111
3112 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3113 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3114 while (cur != NULL) {
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3115 if ((!strcmp(cur-&gt;name, "Person")) &amp;&amp; (cur-&gt;ns == ns))
3116 ret-&gt;name = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3117 if ((!strcmp(cur-&gt;name, "Email")) &amp;&amp; (cur-&gt;ns == ns))
3118 ret-&gt;email = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3119 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3120 }
3121
3122 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3123}</pre>
3124
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3125<p>Here are a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3126<ul>
Daniel Veillard91e9d582001-02-26 07:31:12 +0000[diff] [blame]3127 <li>Usually a recursive parsing style is the more convenient one: XML data
3128 is by nature subject to repetitive constructs and usually exibits highly
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3129 stuctured patterns.</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3130 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>,
3131 i.e. the pointer to the global XML document and the namespace reserved to
3132 the application. Document wide information are needed for example to
3133 decode entities and it's a good coding practice to define a namespace for
3134 your application set of data and test that the element and attributes
3135 you're analyzing actually pertains to your application space. This is
3136 done by a simple equality test (cur-&gt;ns == ns).</li>
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3137 <li>To retrieve text and attributes value, you can use the function
3138 <em>xmlNodeListGetString</em> to gather all the text and entity reference
3139 nodes generated by the DOM output and produce an single text string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3140</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3141
3142<p>Here is another piece of code used to parse another level of the
3143structure:</p>
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3144<pre>#include &lt;libxml/tree.h&gt;
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame]3145/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3146 * a Description for a Job
3147 */
3148typedef struct job {
3149 char *projectID;
3150 char *application;
3151 char *category;
3152 personPtr contact;
3153 int nbDevelopers;
3154 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
3155} job, *jobPtr;
3156
3157/*
3158 * And the code needed to parse it
3159 */
3160jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
3161 jobPtr ret = NULL;
3162
3163DEBUG("parseJob\n");
3164 /*
3165 * allocate the struct
3166 */
3167 ret = (jobPtr) malloc(sizeof(job));
3168 if (ret == NULL) {
3169 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3170 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3171 }
3172 memset(ret, 0, sizeof(job));
3173
3174 /* We don't care what the top level element name is */
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3175 cur = cur-&gt;xmlChildrenNode;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3176 while (cur != NULL) {
3177
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3178 if ((!strcmp(cur-&gt;name, "Project")) &amp;&amp; (cur-&gt;ns == ns)) {
3179 ret-&gt;projectID = xmlGetProp(cur, "ID");
3180 if (ret-&gt;projectID == NULL) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3181 fprintf(stderr, "Project has no ID\n");
3182 }
3183 }
Daniel Veillard60979bd2000-07-10 12:17:33 +0000[diff] [blame]3184 if ((!strcmp(cur-&gt;name, "Application")) &amp;&amp; (cur-&gt;ns == ns))
3185 ret-&gt;application = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3186 if ((!strcmp(cur-&gt;name, "Category")) &amp;&amp; (cur-&gt;ns == ns))
3187 ret-&gt;category = xmlNodeListGetString(doc, cur-&gt;xmlChildrenNode, 1);
3188 if ((!strcmp(cur-&gt;name, "Contact")) &amp;&amp; (cur-&gt;ns == ns))
3189 ret-&gt;contact = parsePerson(doc, ns, cur);
3190 cur = cur-&gt;next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3191 }
3192
3193 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3194}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]3195
Daniel Veillardec70e912001-02-26 20:10:45 +0000[diff] [blame]3196<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]3197boring. Ultimately, it could be possble to write stubbers taking either C
3198data structure definitions, a set of XML examples or an XML DTD and produce
3199the code needed to import and export the content between C data and XML
3200storage. This is left as an exercise to the reader :-)</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3201
Daniel Veillard6f0adb52000-07-03 11:41:26 +0000[diff] [blame]3202<p>Feel free to use <a href="example/gjobread.c">the code for the full C
3203parsing example</a> as a template, it is also available with Makefile in the
3204Gnome CVS base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]3205
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3206<h2><a name="Contributi">Contributions</a></h2>
3207<ul>
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3208 <li>Bjorn Reese, William Brack and Thomas Broyer have provided a number of
3209 patches, Gary Pennington worked on the validation API, threading support
3210 and Solaris port.</li>
3211 <li>John Fleck helps maintaining the documentation and man pages.</li>
3212 <li><p><a href="mailto:ari@lusis.org">Ari Johnson</a></p>
Daniel Veillard9c466822001-10-25 12:03:39 +0000[diff] [blame^]3213 provides a C++ wrapper for libxml:
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3214 <p>Website: <a
3215 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
3216 <p>Download: <a
3217 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
3218 </li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3219 <li><a href="mailto:izlatkovic@daenet.de">Igor Zlatkovic</a>
3220 is now the maintainer of the Windows port, <a
Daniel Veillard95189532001-07-26 18:30:26 +0000[diff] [blame]3221 href="http://www.fh-frankfurt.de/~igor/projects/libxml/index.html">he
3222 provides binaries</a></li>
Daniel Veillardc9484202001-10-24 12:35:52 +0000[diff] [blame]3223 <li><a href="mailto:Gary.Pennington@sun.com">Gary Pennington</a>
3224 provides <a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris
Daniel Veillard0a702dc2001-10-19 14:50:57 +0000[diff] [blame]3225 binaries</a></li>
Daniel Veillarde356c282001-03-10 12:32:04 +0000[diff] [blame]3226 <li><a
3227 href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3228 Sergeant</a>
3229 developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl
3230 wrapper for libxml2/libxslt as part of the <a
3231 href="http://axkit.com/">AxKit XML application server</a></li>
3232 <li><a href="mailto:fnatter@gmx.net">Felix Natter</a>
3233 and <a href="mailto:geertk@ai.rug.nl">Geert Kloosterman</a> provide <a
Daniel Veillardca989762001-06-23 17:39:29 +0000[diff] [blame]3234 href="libxml-doc.el">an emacs module</a> to lookup libxml(2) functions
Daniel Veillard3f6f7f62000-06-30 17:58:25 +0000[diff] [blame]3235 documentation</li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3236 <li><a href="mailto:sherwin@nlm.nih.gov">Ziying Sherwin</a>
3237 provided <a href="http://xmlsoft.org/messages/0488.html">man
3238 pages</a></li>
Daniel Veillard5168dbf2001-07-07 00:18:23 +0000[diff] [blame]3239 <li>there is a module for <a
3240 href="http://acs-misc.sourceforge.net/nsxml.html">libxml/libxslt support
3241 in OpenNSD/AOLServer</a></li>
Daniel Veillard3d6ae1c2001-08-15 13:12:39 +0000[diff] [blame]3242 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>
3243 provides libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers
3244 for Python</a></li>
Daniel Veillardc310d562000-06-23 18:32:15 +0000[diff] [blame]3245</ul>
3246
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3247<p></p>
3248
Daniel Veillardf7ed3362001-08-17 12:01:21 +0000[diff] [blame]3249<p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]3250
Daniel Veillardb8cfbd12001-10-25 10:53:28 +0000[diff] [blame]3251<p>$Id: xml.html,v 1.114 2001/10/24 12:35:52 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3252</body>
3253</html>