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blob: 3f03d7a08b2e10a8283e9299bc1de5b2f18010ce [file] [log] [blame]
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]2 "http://www.w3.org/TR/REC-html40/loose.dtd">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]3<html>
4<head>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]5 <title>The XML library for Gnome</title>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]6 <meta name="GENERATOR" content="amaya V2.4">
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 Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]11<p><a href="http://www.gnome.org/"><img src="smallfootonly.gif" alt="Gnome
12Logo"></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C
13Logo"></a></p>
14
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]15<h1 align="center">The XML library for Gnome</h1>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]16
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]17<h2 style="text-align: center">libxml, a.k.a. gnome-xml</h2>
18
19<p></p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]20<ul>
21 <li><a href="#Introducti">Introduction</a></li>
22 <li><a href="#Documentat">Documentation</a></li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]23 <li><a href="#Downloads">Downloads</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]24 <li><a href="#News">News</a></li>
25 <li><a href="#XML">XML</a></li>
26 <li><a href="#tree">The tree output</a></li>
27 <li><a href="#interface">The SAX interface</a></li>
28 <li><a href="#library">The XML library interfaces</a>
29 <ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]30 <li><a href="#Invoking">Invoking the parser: the pull way</a></li>
31 <li><a href="#Invoking">Invoking the parser: the push way</a></li>
32 <li><a href="#Invoking2">Invoking the parser: the SAX interface</a></li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]33 <li><a href="#Building">Building a tree from scratch</a></li>
34 <li><a href="#Traversing">Traversing the tree</a></li>
35 <li><a href="#Modifying">Modifying the tree</a></li>
36 <li><a href="#Saving">Saving the tree</a></li>
37 <li><a href="#Compressio">Compression</a></li>
38 </ul>
39 </li>
40 <li><a href="#Entities">Entities or no entities</a></li>
41 <li><a href="#Namespaces">Namespaces</a></li>
42 <li><a href="#Validation">Validation</a></li>
43 <li><a href="#Principles">DOM principles</a></li>
44 <li><a href="#real">A real example</a></li>
45</ul>
46
47<h2><a name="Introducti">Introduction</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]48
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]49<p>This document describes libxml, the <a
50href="http://www.w3.org/XML/">XML</a> library provided in the <a
51href="http://www.gnome.org/">Gnome</a> framework. XML is a standard for
52building tag-based structured documents/data.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]53
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]54<p>Here are some key points about libxml:</p>
55<ul>
56 <li>The internal document repesentation is as close as possible to the <a
57 href="http://www.w3.org/DOM/">DOM</a> interfaces.</li>
58 <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]59 like interface</a>; the interface is designed to be compatible with <a
60 href="http://www.jclark.com/xml/expat.html">Expat</a>.</li>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]61 <li>Libxml now includes a nearly complete <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]62 href="http://www.w3.org/TR/xpath">XPath</a> implementation.</li>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]63 <li>Libxml exports Push and Pull type parser interfaces for both XML and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]64 HTML.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]65 <li>This library is released both under the <a
66 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
67 IPR</a> and the GNU LGPL. Use either at your convenience, basically this
68 should make everybody happy, if not, drop me a mail.</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]69 <li>There is <a href="upgrade.html">a first set of instruction</a>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]70 concerning upgrade from libxml-1.x to libxml-2.x</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]71</ul>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]72
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]73<h2><a name="Documentat">Documentation</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]74
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]75<p>There are some on-line resources about using libxml:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]76<ol>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]77 <li>The code is commented in a way which allows <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]78 href="http://xmlsoft.org/libxml.html">extensive documentation</a> to be
79 automatically extracted.</li>
80 <li>This page provides a global overview and <a href="#real">some
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]81 examples</a> on how to use libxml.</li>
82 <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a
83 href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice
84 documentation</a> explaining how to use the libxml SAX interface.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]85 <li>George Lebl wrote <a
86 href="http://www-4.ibm.com/software/developer/library/gnome3/">an article
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]87 for IBM developerWorks</a> about using libxml.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]88 <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph
89 Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is
90 building the <a href="http://levien.com/gnome/gdome.html">DOM interface
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]91 gdome</a> on top of libxml result tree and an implementation of <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]92 href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a
93 href="http://www.levien.com/svg/">gill</a>. Check his <a
94 href="http://www.levien.com/gnome/domination.html">DOMination
95 paper</a>.</li>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]96 <li>Check <a href="http://cvs.gnome.org/lxr/source/gnome-xml/TODO">the TODO
97 file</a></li>
98 <li>Read the <a href="upgrade.html">1.x to 2.x upgrade path</a>. If you are
99 starting a new project using libxml you should really use the 2.x
100 version.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]101 <li>And don't forget to look at the <a href="/messages/">mailing-list
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]102 archive</a>, too.</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]103</ol>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]104
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]105<h3>Reporting bugs and getting help</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]106
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]107<p>Well, bugs or missing features are always possible, and I will make a point
108of fixing them in a timely fashion. The best way to report a bug is to <a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]109href="http://bugs.gnome.org/db/pa/lgnome-xml.html">use the Gnome bug tracking
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]110database</a>. I look at reports there regularly and it's good to have a
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]111reminder when a bug is still open. Check the <a
112href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a>
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]113and be sure to specify that the bug is for the package gnome-xml.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]114
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]115<p>There is also a mailing-list <a
116href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> for libxml, with an <a
117href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]118majordomo based list, send a mail message to <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]119href="mailto:majordomo@rufus.w3.org">majordomo@rufus.w3.org</a> with
120"subscribe xml" in the <strong>content</strong> of the message.</p>
121
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]122<p>Alternatively, you can just send the bug to the <a
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]123href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> list.</p>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]124
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]125<p>Of course, bugs reports with a suggested patch for fixing them will
126probably be processed faster.</p>
127
128<p>If you're looking for help, a quick look at <a
129href="http://xmlsoft.org/messages/#407">the list archive</a> may actually
130provide the answer, I usually send source samples when answering libxml usage
131questions. The <a href="http://xmlsoft.org/book1.html">auto-generated
132documentantion</a> is not as polished as I would like (i need to learn more
133about Docbook), but it's a good starting point.</p>
134
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]135<h2><a name="Downloads">Downloads</a></h2>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]136
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]137<p>The latest versions of libxml can be found on <a
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]138href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or on the <a
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]139href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]140as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]141archive</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/contrib/rpms/">RPMs
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]142packages</a>. (NOTE that you need both the <a
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]143href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
144href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]145packages installed to compile applications using libxml.)</p>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]146
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]147<p><a name="Snapshot">Snapshot:</a></p>
148<ul>
149 <li>Code from the W3C cvs base libxml <a
150 href="ftp://rpmfind.net/pub/libxml/cvs-snapshot.tar.gz">cvs-snapshot.tar.gz</a></li>
151 <li>Docs, content of the web site, the list archive included <a
152 href="ftp://rpmfind.net/pub/libxml/libxml-docs.tar.gz">libxml-docs.tar.gz</a></li>
153</ul>
154
155<p><a name="Contribs">Contribs:</a></p>
156
157<p>I do accept external contributions, especially if compiling on another
158platform, get in touch with me to upload the package. I will keep them in the
159<a href="ftp://rpmfind.net/pub/libxml/contribs/">contrib directory</a></p>
160
161<p>Libxml is also available from 2 CVs bases:</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]162<ul>
163 <li><p>The <a href="http://dev.w3.org/cvsweb/XML/">W3C CVS base</a>,
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]164 available read-only using the CVS pserver authentification (I tend to use
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]165 this base for my own development, so it's updated more regularly, but the
166 content may not be as stable):</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]167 <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]168 password: anonymous
169 module: XML</pre>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]170 </li>
171 <li><p>The <a
172 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]173 CVS base</a>. Check the <a
174 href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page;
175 the CVS module is <b>gnome-xml</b>.</p>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]176 </li>
177</ul>
178
179<h2><a name="News">News</a></h2>
180
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]181<h3>CVS only : check the <a
182href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file
183for really accurate description</h3>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]184<ul>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]185 <li>working on HTML and XML links recognition layers, get in touch with me
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]186 if you want to test those.</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]187 <li>So far the feedback on the libxml2 beta is positive</li>
188</ul>
189
190<h3>2.0.0: Apr 3 2000</h3>
191<ul>
192 <li>First public release of libxml2. If you are using libxml, it's a good
193 idea to check the 1.x to 2.x upgrade instructions</li>
194 <li>The include are now located under $prefix/include/libxml (instead of
195 $prefix/include/gnome-xml), they also are referenced by
196 <pre>#include &lt;libxml/xxx.h></pre>
197 <p>instead of </p>
198 <pre>#include "xxx.h"</pre>
199 </li>
Daniel Veillard8f621982000-03-20 13:07:15 +0000[diff] [blame]200 <li>a new URI module for parsing URIs and following strictly RFC 2396</li>
201 <li>the memory allocation routines used by libxml can now be overloaded
202 dynamically by using xmlMemSetup()</li>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]203 <li>The previously CVS only tool tester has been renamed
204 <strong>xmllint</strong> and is now installed as part of the libxml2
205 package</li>
206 <li></li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]207</ul>
208
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]209<p> </p>
210
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]211<h3>2.0.0beta: Mar 14 2000</h3>
212<ul>
213 <li>This is a first Beta release of libxml version 2</li>
214 <li>It's available only from<a href="ftp://rpmfind.net/pub/libxml/">
215 rpmfind.net FTP</a>, it's packaged as libxml2-2.0.0beta and available as
216 tar and RPMs</li>
217 <li>This version is now the head in the Gnome CVS base, the old one is
218 available under the tag LIB_XML_1_X</li>
219 <li>This includes a very large set of changes. Froma programmatic point of
220 view applications should not have to be modified too much, check the <a
221 href="upgrade.html">upgrade page</a></li>
222 <li>Some interfaces may changes (especially a bit about encoding).</li>
223 <li>the updates includes:
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]224 <ul>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]225 <li>fix I18N support. ISO-Latin-x/UTF-8/UTF-16 (nearly) seems correctly
226 handled now</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]227 <li>Better handling of entities, especially well formedness checking and
228 proper PEref extensions in external subsets</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]229 <li>DTD conditional sections</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]230 <li>Validation now correcly handle entities content</li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]231 <li><a href="http://rpmfind.net/tools/gdome/messages/0039.html">change
232 structures to accomodate DOM</a></li>
Daniel Veillard6c8b1172000-03-01 00:40:41 +0000[diff] [blame]233 </ul>
234 </li>
Daniel Veillardedfb29b2000-03-14 19:59:05 +0000[diff] [blame]235 <li>Serious progress were made toward compliance, <a
236 href="conf/result.html">here are the result of the test</a> against the
237 OASIS testsuite (except the japanese tests since I don't support that
238 encoding yet). This URL is rebuilt every couple of hours using the CVS
239 head version.</li>
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]240</ul>
241
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]242<h3>1.8.7: Mar 6 2000</h3>
243<ul>
244 <li>This is a bug fix release:</li>
245 <li>It is possible to disable the ignorable blanks heuristic used by
246 libxml-1.x, a new function xmlKeepBlanksDefault(0) will allow this. Note
247 that for adherence to XML spec, this behaviour will be disabled by default
248 in 2.x . The same function will allow to keep compatibility for old
249 code.</li>
250 <li>Blanks in &lt;a> &lt;/a> constructs are not ignored anymore, avoiding
251 heuristic is really the Right Way :-\</li>
252 <li>The unchecked use of snprintf which was breaking libxml-1.8.6
253 compilation on some platforms has been fixed</li>
254 <li>nanoftp.c nanohttp.c: Fixed '#' and '?' stripping when processing
255 URIs</li>
256</ul>
257
Daniel Veillarde41f2b72000-01-30 20:00:07 +0000[diff] [blame]258<h3>1.8.6: Jan 31 2000</h3>
259<ul>
260 <li>added a nanoFTP transport module, debugged until the new version of <a
261 href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use
262 it without troubles</li>
Daniel Veillardda07c342000-01-25 18:31:22 +0000[diff] [blame]263</ul>
264
265<h3>1.8.5: Jan 21 2000</h3>
266<ul>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]267 <li>adding APIs to parse a well balanced chunk of XML (production <a
268 href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML
269 spec)</li>
Daniel Veillard461a66c2000-01-18 18:01:01 +0000[diff] [blame]270 <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li>
271 <li>Jody Goldberg &lt;jgoldberg@home.com> provided another patch trying to
272 solve the zlib checks problems</li>
273 <li>The current state in gnome CVS base is expected to ship as 1.8.5 with
274 gnumeric soon</li>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]275</ul>
276
277<h3>1.8.4: Jan 13 2000</h3>
278<ul>
279 <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li>
280 <li>all exit() call should have been removed from libxml</li>
281 <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li>
282 <li>added newDocFragment()</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]283</ul>
284
285<h3>1.8.3: Jan 5 2000</h3>
286<ul>
287 <li>a Push interface for the XML and HTML parsers</li>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]288 <li>a shell-like interface to the document tree (try tester --shell :-)</li>
Daniel Veillarddbfd6411999-12-28 16:35:14 +0000[diff] [blame]289 <li>lots of bug fixes and improvement added over XMas hollidays</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]290 <li>fixed the DTD parsing code to work with the xhtml DTD</li>
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]291 <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li>
292 <li>Fixed bugs in xmlNewNs()</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]293 <li>External entity loading code has been revamped, now it uses
Daniel Veillardf84f71f2000-01-05 19:54:23 +0000[diff] [blame]294 xmlLoadExternalEntity(), some fix on entities processing were added</li>
Daniel Veillard437b87b2000-01-03 17:30:46 +0000[diff] [blame]295 <li>cleaned up WIN32 includes of socket stuff</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]296</ul>
297
298<h3>1.8.2: Dec 21 1999</h3>
299<ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]300 <li>I got another problem with includes and C++, I hope this issue is fixed
301 for good this time</li>
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]302 <li>Added a few tree modification functions: xmlReplaceNode,
303 xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and
304 xmlDocSetRootElement</li>
305 <li>Tried to improve the HTML output with help from <a
306 href="mailto:clahey@umich.edu">Chris Lahey</a></li>
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]307</ul>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]308
Daniel Veillarde4e51311999-12-18 15:32:46 +0000[diff] [blame]309<h3>1.8.1: Dec 18 1999</h3>
310<ul>
311 <li>various patches to avoid troubles when using libxml with C++ compilers
312 the "namespace" keyword and C escaping in include files</li>
313 <li>a problem in one of the core macros IS_CHAR was corrected</li>
314 <li>fixed a bug introduced in 1.8.0 breaking default namespace processing,
315 and more specifically the Dia application</li>
Daniel Veillard944b5ff1999-12-15 19:08:24 +0000[diff] [blame]316 <li>fixed a posteriori validation (validation after parsing, or by using a
317 Dtd not specified in the original document)</li>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]318 <li>fixed a bug in</li>
Daniel Veillard10a2c651999-12-12 13:03:50 +0000[diff] [blame]319</ul>
320
321<h3>1.8.0: Dec 12 1999</h3>
322<ul>
323 <li>cleanup, especially memory wise</li>
324 <li>the parser should be more reliable, especially the HTML one, it should
325 not crash, whatever the input !</li>
326 <li>Integrated various patches, especially a speedup improvement for large
327 dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>,
328 configure with --with-buffers to enable them.</li>
329 <li>attribute normalization, oops should have been added long ago !</li>
330 <li>attributes defaulted from Dtds should be available, xmlSetProp() now
331 does entities escapting by default.</li>
Daniel Veillard4c3a2031999-11-19 17:46:26 +0000[diff] [blame]332</ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]333
334<h3>1.7.4: Oct 25 1999</h3>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]335<ul>
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]336 <li>Lots of HTML improvement</li>
337 <li>Fixed some errors when saving both XML and HTML</li>
338 <li>More examples, the regression tests should now look clean</li>
339 <li>Fixed a bug with contiguous charref</li>
340</ul>
341
342<h3>1.7.3: Sep 29 1999</h3>
343<ul>
344 <li>portability problems fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]345 <li>snprintf was used unconditionnally, leading to link problems on system
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]346 were it's not available, fixed</li>
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]347</ul>
348
349<h3>1.7.1: Sep 24 1999</h3>
350<ul>
351 <li>The basic type for strings manipulated by libxml has been renamed in
352 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason
353 is that CHAR was conflicting with a predefined type on Windows. However on
354 non WIN32 environment, compatibility is provided by the way of a
355 <strong>#define </strong>.</li>
356 <li>Changed another error : the use of a structure field called errno, and
357 leading to troubles on platforms where it's a macro</li>
358</ul>
359
360<h3>1.7.0: sep 23 1999</h3>
361<ul>
362 <li>Added the ability to fetch remote DTD or parsed entities, see the <a
363 href="gnome-xml-nanohttp.html">nanohttp</a> module.</li>
364 <li>Added an errno to report errors by another mean than a simple printf
365 like callback</li>
366 <li>Finished ID/IDREF support and checking when validation</li>
367 <li>Serious memory leaks fixed (there is now a <a
368 href="gnome-xml-xmlmemory.html">memory wrapper</a> module)</li>
369 <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a>
370 implementation</li>
371 <li>Added an HTML parser front-end</li>
372</ul>
373
374<h2><a name="XML">XML</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]375
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]376<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]377markup-based structured documents. Here is <a name="example">an example XML
378document</a>:</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]379<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]380&lt;EXAMPLE prop1="gnome is great" prop2="&amp;amp; linux too">
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]381 &lt;head>
382 &lt;title>Welcome to Gnome&lt;/title>
383 &lt;/head>
384 &lt;chapter>
385 &lt;title>The Linux adventure&lt;/title>
386 &lt;p>bla bla bla ...&lt;/p>
387 &lt;image href="linus.gif"/>
388 &lt;p>...&lt;/p>
389 &lt;/chapter>
390&lt;/EXAMPLE></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]391
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]392<p>The first line specifies that it's an XML document and gives useful
393information about its encoding. Then the document is a text format whose
394structure is specified by tags between brackets. <strong>Each tag opened has
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]395to be closed</strong>. XML is pedantic about this. However, if a tag is empty
396(no content), a single tag can serve as both the opening and closing tag if it
397ends with <code>/></code> rather than with <code>></code>. Note that, for
398example, the image tag has no content (just an attribute) and is closed by
399ending the tag with <code>/></code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]400
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]401<p>XML can be applied sucessfully to a wide range of uses, from long term
402structured document maintenance (where it follows the steps of SGML) to simple
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]403data encoding mechanisms like configuration file formatting (glade),
404spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
405it is used to encode remote calls between a client and a server.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]406
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]407<h2><a name="tree">The tree output</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]408
409<p>The parser returns a tree built during the document analysis. The value
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]410returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]411<strong>xmlDoc</strong> structure). This structure contains information such
412as the file name, the document type, and a <strong>root</strong> pointer which
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]413is the root of the document (or more exactly the first child under the root
414which is the document). The tree is made of <strong>xmlNode</strong>s, chained
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]415in double-linked lists of siblings and with childs&lt;->parent relationship.
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]416An xmlNode can also carry properties (a chain of xmlAttr structures). An
417attribute may have a value which is a list of TEXT or ENTITY_REF nodes.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]418
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]419<p>Here is an example (erroneous with respect to the XML spec since there
420should be only one ELEMENT under the root):</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]421
422<p><img src="structure.gif" alt=" structure.gif "></p>
423
424<p>In the source package there is a small program (not installed by default)
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]425called <strong>xmllint</strong> which parses XML files given as argument and
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]426prints them back as parsed. This is useful for detecting errors both in XML
427code and in the XML parser itself. It has an option <strong>--debug</strong>
428which prints the actual in-memory structure of the document, here is the
429result with the <a href="#example">example</a> given before:</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]430<pre>DOCUMENT
431version=1.0
432standalone=true
433 ELEMENT EXAMPLE
434 ATTRIBUTE prop1
435 TEXT
436 content=gnome is great
437 ATTRIBUTE prop2
438 ENTITY_REF
439 TEXT
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]440 content= linux too
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]441 ELEMENT head
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]442 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]443 TEXT
444 content=Welcome to Gnome
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]445 ELEMENT chapter
446 ELEMENT title
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]447 TEXT
448 content=The Linux adventure
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]449 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]450 TEXT
451 content=bla bla bla ...
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]452 ELEMENT image
453 ATTRIBUTE href
454 TEXT
455 content=linus.gif
456 ELEMENT p
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]457 TEXT
458 content=...</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]459
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]460<p>This should be useful for learning the internal representation model.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]461
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]462<h2><a name="interface">The SAX interface</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]463
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]464<p>Sometimes the DOM tree output is just too large to fit reasonably into
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]465memory. In that case (and if you don't expect to save back the XML document
466loaded using libxml), it's better to use the SAX interface of libxml. SAX is a
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]467<strong>callback-based interface</strong> to the parser. Before parsing, the
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]468application layer registers a customized set of callbacks which are called by
469the library as it progresses through the XML input.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]470
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]471<p>To get more detailed step-by-step guidance on using the SAX interface of
472libxml, see the
473href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]474documentation.written by <a href="mailto:james@daa.com.au">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]475Henstridge</a>.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]476
477<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
478program located in the gnome-xml module (it's usually not shipped in the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]479binary packages of libxml, but you can find it in the tar source
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]480distribution). Here is the sequence of callbacks that would be reported by
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]481testSAX when parsing the example XML document shown earlier:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]482<pre>SAX.setDocumentLocator()
483SAX.startDocument()
484SAX.getEntity(amp)
485SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
486SAX.characters( , 3)
487SAX.startElement(head)
488SAX.characters( , 4)
489SAX.startElement(title)
490SAX.characters(Welcome to Gnome, 16)
491SAX.endElement(title)
492SAX.characters( , 3)
493SAX.endElement(head)
494SAX.characters( , 3)
495SAX.startElement(chapter)
496SAX.characters( , 4)
497SAX.startElement(title)
498SAX.characters(The Linux adventure, 19)
499SAX.endElement(title)
500SAX.characters( , 4)
501SAX.startElement(p)
502SAX.characters(bla bla bla ..., 15)
503SAX.endElement(p)
504SAX.characters( , 4)
505SAX.startElement(image, href='linus.gif')
506SAX.endElement(image)
507SAX.characters( , 4)
508SAX.startElement(p)
509SAX.characters(..., 3)
510SAX.endElement(p)
511SAX.characters( , 3)
512SAX.endElement(chapter)
513SAX.characters( , 1)
514SAX.endElement(EXAMPLE)
515SAX.endDocument()</pre>
516
Daniel Veillard402e8c82000-02-29 22:57:47 +0000[diff] [blame]517<p>Most of the other functionalities of libxml are based on the DOM
518tree-building facility, so nearly everything up to the end of this document
519presupposes the use of the standard DOM tree build. Note that the DOM tree
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]520itself is built by a set of registered default callbacks, without internal
521specific interface.</p>
522
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]523<h2><a name="library">The XML library interfaces</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]524
525<p>This section is directly intended to help programmers getting bootstrapped
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]526using the XML library from the C language. It is not intended to be extensive.
527I hope the automatically generated documents will provide the completeness
528required, but as a separate set of documents. The interfaces of the XML
529library are by principle low level, there is nearly zero abstraction. Those
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]530interested in a higher level API should <a href="#DOM">look at DOM</a>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]531
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]532<p>The <a href="gnome-xml-parser.html">parser interfaces for XML</a> are
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]533separated from the <a href="gnome-xml-htmlparser.html">HTML parser
534interfaces</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]535
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]536<h3><a name="Invoking">Invoking the parser : the pull method</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]537
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]538<p>Usually, the first thing to do is to read an XML input. The parser accepts
539documents either from in-memory strings or from files. The functions are
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]540defined in "parser.h":</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]541<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]542 <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]543 <dd><p>Parse a null-terminated string containing the document.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]544 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]545</dl>
546<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]547 <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]548 <dd><p>Parse an XML document contained in a (possibly compressed)
549 file.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]550 </dd>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]551</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]552
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]553<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]554failure).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]555
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]556<h3 id="Invoking1">Invoking the parser: the push method</h3>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]557
558<p>In order for the application to keep the control when the document is been
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]559fetched (which is common for GUI based programs) libxml provides a push
560interface, too, as of version 1.8.3. Here are the interface functions:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]561<pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax,
562 void *user_data,
563 const char *chunk,
564 int size,
565 const char *filename);
566int xmlParseChunk (xmlParserCtxtPtr ctxt,
567 const char *chunk,
568 int size,
569 int terminate);</pre>
570
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]571<p>and here is a simple example showing how to use the interface:</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]572<pre> FILE *f;
573
574 f = fopen(filename, "r");
575 if (f != NULL) {
576 int res, size = 1024;
577 char chars[1024];
578 xmlParserCtxtPtr ctxt;
579
580 res = fread(chars, 1, 4, f);
581 if (res > 0) {
582 ctxt = xmlCreatePushParserCtxt(NULL, NULL,
583 chars, res, filename);
584 while ((res = fread(chars, 1, size, f)) > 0) {
585 xmlParseChunk(ctxt, chars, res, 0);
586 }
587 xmlParseChunk(ctxt, chars, 0, 1);
588 doc = ctxt->myDoc;
589 xmlFreeParserCtxt(ctxt);
590 }
591 }</pre>
592
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]593<p>Also note that the HTML parser embedded into libxml also has a push
594interface; the functions are just prefixed by "html" rather than "xml"</p>
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]595
596<h3 id="Invoking2">Invoking the parser: the SAX interface</h3>
597
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]598<p>A couple of comments can be made, first this mean that the parser is
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]599memory-hungry, first to load the document in memory, second to build the tree.
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]600Reading a document without building the tree is possible using the SAX
601interfaces (see SAX.h and <a
602href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]603Henstridge's documentation</a>). Note also that the push interface can be
604limited to SAX. Just use the two first arguments of
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]605<code>xmlCreatePushParserCtxt()</code>.</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]606
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]607<h3><a name="Building">Building a tree from scratch</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]608
609<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]610there is a set of functions dedicated to building new elements. (These are
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]611also described in &lt;libxml/tree.h>.) For example, here is a piece of code
612that produces the XML document used in the previous examples:</p>
613<pre> #include &lt;libxml/tree.h>
614 xmlDocPtr doc;
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]615 xmlNodePtr tree, subtree;
616
617 doc = xmlNewDoc("1.0");
618 doc->root = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL);
619 xmlSetProp(doc->root, "prop1", "gnome is great");
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]620 xmlSetProp(doc->root, "prop2", "&amp; linux too");
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]621 tree = xmlNewChild(doc->root, NULL, "head", NULL);
622 subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome");
623 tree = xmlNewChild(doc->root, NULL, "chapter", NULL);
624 subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure");
625 subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ...");
626 subtree = xmlNewChild(tree, NULL, "image", NULL);
627 xmlSetProp(subtree, "href", "linus.gif");</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]628
629<p>Not really rocket science ...</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]630
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]631<h3><a name="Traversing">Traversing the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]632
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]633<p>Basically by <a href="gnome-xml-tree.html">including "tree.h"</a> your code
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]634has access to the internal structure of all the elements of the tree. The
635names should be somewhat simple like <strong>parent</strong>,
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]636<strong>childs</strong>, <strong>next</strong>, <strong>prev</strong>,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]637<strong>properties</strong>, etc... For example, still with the previous
Daniel Veillard0142b842000-01-14 14:45:24 +0000[diff] [blame]638example:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]639<pre><code>doc->root->childs->childs</code></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]640
641<p>points to the title element,</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]642<pre>doc->root->childs->next->child->child</pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]643
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]644<p>points to the text node containing the chapter title "The Linux
645adventure".</p>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]646
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]647<p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]648present before the document root, so <code>doc->root</code> may point to an
649element which is not the document Root Element, a function
Daniel Veillard5cb5ab81999-12-21 15:35:29 +0000[diff] [blame]650<code>xmlDocGetRootElement()</code> was added for this purpose.</p>
Daniel Veillardb24054a1999-12-18 15:32:46 +0000[diff] [blame]651
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]652<h3><a name="Modifying">Modifying the tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]653
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]654<p>Functions are provided for reading and writing the document content. Here
655is an excerpt from the <a href="gnome-xml-tree.html">tree API</a>:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]656<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]657 <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const
658 xmlChar *value);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]659 <dd><p>This sets (or changes) an attribute carried by an ELEMENT node. The
660 value can be NULL.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]661 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]662</dl>
663<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]664 <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]665 *name);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]666 <dd><p>This function returns a pointer to the property content. Note that
667 no extra copy is made.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]668 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]669</dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]670
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]671<p>Two functions are provided for reading and writing the text associated with
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]672elements:</p>
673<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]674 <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]675 *value);</code></dt>
676 <dd><p>This function takes an "external" string and convert it to one text
677 node or possibly to a list of entity and text nodes. All non-predefined
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]678 entity references like &amp;Gnome; will be stored internally as entity
679 nodes, hence the result of the function may not be a single node.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]680 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]681</dl>
682<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]683 <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]684 inLine);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]685 <dd><p>This function is the inverse of
686 <code>xmlStringGetNodeList()</code>. It generates a new string
687 containing the content of the text and entity nodes. Note the extra
688 argument inLine. If this argument is set to 1, the function will expand
689 entity references. For example, instead of returning the &amp;Gnome;
690 XML encoding in the string, it will substitute it with its value (say,
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]691 "GNU Network Object Model Environment"). Set this argument if you want
692 to use the string for non-XML usage like User Interface.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]693 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]694</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]695
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]696<h3><a name="Saving">Saving a tree</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]697
698<p>Basically 3 options are possible:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]699<dl>
Daniel Veillarddd6b3671999-09-23 22:19:22 +0000[diff] [blame]700 <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]701 *size);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]702 <dd><p>Returns a buffer into which the document has been saved.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]703 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]704</dl>
705<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]706 <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]707 <dd><p>Dumps a document to an open file descriptor.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]708 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]709</dl>
710<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]711 <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt>
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]712 <dd><p>Saves the document to a file. In this case, the compression
713 interface is triggered if it has been turned on.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]714 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]715</dl>
Daniel Veillard10c6a8f1998-10-28 01:00:12 +0000[diff] [blame]716
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]717<h3><a name="Compressio">Compression</a></h3>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]718
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]719<p>The library transparently handles compression when doing file-based
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]720accesses. The level of compression on saves can be turned on either globally
721or individually for one file:</p>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]722<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]723 <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]724 <dd><p>Gets the document compression ratio (0-9).</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]725 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]726</dl>
727<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]728 <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]729 <dd><p>Sets the document compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]730 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]731</dl>
732<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]733 <dt><code>int xmlGetCompressMode(void);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]734 <dd><p>Gets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]735 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]736</dl>
737<dl>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]738 <dt><code>void xmlSetCompressMode(int mode);</code></dt>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]739 <dd><p>Sets the default compression ratio.</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]740 </dd>
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]741</dl>
742
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]743<h2><a name="Entities">Entities or no entities</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]744
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]745<p>Entities in principle are similar to simple C macros. An entity defines an
746abbreviation for a given string that you can reuse many times throughout the
747content of your document. Entities are especially useful when a given string
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]748may occur frequently within a document, or to confine the change needed to a
749document to a restricted area in the internal subset of the document (at the
750beginning). Example:</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]751<pre>1 &lt;?xml version="1.0"?>
7522 &lt;!DOCTYPE EXAMPLE SYSTEM "example.dtd" [
7533 &lt;!ENTITY xml "Extensible Markup Language">
7544 ]>
7555 &lt;EXAMPLE>
7566 &amp;xml;
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]7577 &lt;/EXAMPLE></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]758
759<p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]760it's name with '&amp;' and following it by ';' without any spaces added. There
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]761are 5 predefined entities in libxml allowing you to escape charaters with
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]762predefined meaning in some parts of the xml document content:
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]763<strong>&amp;lt;</strong> for the character '&lt;', <strong>&amp;gt;</strong>
764for the character '>', <strong>&amp;apos;</strong> for the character ''',
765<strong>&amp;quot;</strong> for the character '"', and
766<strong>&amp;amp;</strong> for the character '&amp;'.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]767
768<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]769substitute an entity's content so that you can see the replacement text in
770your application. Or you may prefer to keep entity references as such in the
771content to be able to save the document back without losing this usually
772precious information (if the user went through the pain of explicitly defining
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]773entities, he may have a a rather negative attitude if you blindly susbtitute
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]774them as saving time). The <a
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]775href="gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a>
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]776function allows you to check and change the behaviour, which is to not
777substitute entities by default.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]778
779<p>Here is the DOM tree built by libxml for the previous document in the
780default case:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]781<pre>/gnome/src/gnome-xml -> ./xmllint --debug test/ent1
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]782DOCUMENT
783version=1.0
784 ELEMENT EXAMPLE
785 TEXT
786 content=
787 ENTITY_REF
788 INTERNAL_GENERAL_ENTITY xml
789 content=Extensible Markup Language
790 TEXT
791 content=</pre>
792
793<p>And here is the result when substituting entities:</p>
794<pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1
795DOCUMENT
796version=1.0
797 ELEMENT EXAMPLE
798 TEXT
799 content= Extensible Markup Language</pre>
800
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]801<p>So, entities or no entities? Basically, it depends on your use case. I
802suggest that you keep the non-substituting default behaviour and avoid using
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]803entities in your XML document or data if you are not willing to handle the
804entity references elements in the DOM tree.</p>
805
806<p>Note that at save time libxml enforce the conversion of the predefined
807entities where necessary to prevent well-formedness problems, and will also
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]808transparently replace those with chars (i.e., it will not generate entity
809reference elements in the DOM tree or call the reference() SAX callback when
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]810finding them in the input).</p>
811
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]812<h2><a name="Namespaces">Namespaces</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]813
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]814<p>The libxml library implements <a
815href="http://www.w3.org/TR/REC-xml-names/">XML namespaces</a> support by
816recognizing namespace contructs in the input, and does namespace lookup
817automatically when building the DOM tree. A namespace declaration is
818associated with an in-memory structure and all elements or attributes within
819that namespace point to it. Hence testing the namespace is a simple and fast
820equality operation at the user level.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]821
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]822<p>I suggest that people using libxml use a namespace, and declare it in the
823root element of their document as the default namespace. Then they don't need
824to use the prefix in the content but we will have a basis for future semantic
825refinement and merging of data from different sources. This doesn't augment
826significantly the size of the XML output, but significantly increase its value
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]827in the long-term. Example:</p>
828<pre>&lt;mydoc xmlns="http://mydoc.example.org/schemas/">
829 &lt;elem1>...&lt;/elem1>
830 &lt;elem2>...&lt;/elem2>
831&lt;/mydoc></pre>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]832
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]833<p>Concerning the namespace value, this has to be an URL, but the URL doesn't
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]834have to point to any existing resource on the Web. It will bind all the
835element and atributes with that URL. I suggest to use an URL within a domain
836you control, and that the URL should contain some kind of version information
837if possible. For example, <code>"http://www.gnome.org/gnumeric/1.0/"</code> is
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]838a good namespace scheme.</p>
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]839
840<p>Then when you load a file, make sure that a namespace carrying the
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]841version-independent prefix is installed on the root element of your document,
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]842and if the version information don't match something you know, warn the user
843and be liberal in what you accept as the input. Also do *not* try to base
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]844namespace checking on the prefix value. &lt;foo:text> may be exactly the same
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]845as &lt;bar:text> in another document. What really matter is the URI associated
846with the element or the attribute, not the prefix string (which is just a
Daniel Veillardec303412000-03-24 13:41:54 +0000[diff] [blame]847shortcut for the full URI). In libxml element and attributes have a
848<code>ns</code> field pointing to an xmlNs structure detailing the namespace
849prefix and it's URI.</p>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]850
851<p>@@Interfaces@@</p>
852
853<p>@@Examples@@</p>
854
855<p>Usually people object using namespace in the case of validation, I object
856this and will make sure that using namespaces won't break validity checking,
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]857so even is you plan to use or currently are using validation I strongly
858suggest adding namespaces to your document. A default namespace scheme
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]859<code>xmlns="http://...."</code> should not break validity even on less
Daniel Veillard88f00ae2000-03-02 00:15:55 +0000[diff] [blame]860flexible parsers. Now using namespace to mix and differentiate content coming
861from multiple DTDs will certainly break current validation schemes. I will try
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]862to provide ways to do this, but this may not be portable or standardized.</p>
863
Daniel Veillard2f4dfc41999-09-24 14:03:48 +0000[diff] [blame]864<h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]865
866<p>Well what is validation and what is a DTD ?</p>
867
868<p>Validation is the process of checking a document against a set of
869construction rules, a <strong>DTD</strong> (Document Type Definition) is such
870a set of rules.</p>
871
872<p>The validation process and building DTDs are the two most difficult parts
873of XML life cycle. Briefly a DTD defines all the possibles element to be
874found within your document, what is the formal shape of your document tree (by
875defining the allowed content of an element, either text, a regular expression
876for the allowed list of children, or mixed content i.e. both text and childs).
877The DTD also defines the allowed attributes for all elements and the types of
878the attributes. For more detailed informations, I suggest to read the related
879parts of the XML specification, the examples found under
880gnome-xml/test/valid/dtd and the large amount of books available on XML. The
881dia example in gnome-xml/test/valid should be both simple and complete enough
882to allow you to build your own.</p>
883
884<p>A word of warning, building a good DTD which will fit your needs of your
885application in the long-term is far from trivial, however the extra level of
886quality it can insure is well worth the price for some sets of applications or
887if you already have already a DTD defined for your application field.</p>
888
889<p>The validation is not completely finished but in a (very IMHO) usable
890state. Until a real validation interface is defined the way to do it is to
891define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external
892variable to 1, this will of course be changed at some point:</p>
893
894<p>extern int xmlDoValidityCheckingDefaultValue;</p>
895
896<p>...</p>
897
898<p>xmlDoValidityCheckingDefaultValue = 1;</p>
899
900<p></p>
901
902<p>To handle external entities, use the function
903<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
904link in you HTTP/FTP/Entities database library to the standard libxml
905core.</p>
906
907<p>@@interfaces@@</p>
908
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]909<h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]910
911<p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document Object
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]912Model</em> this is an API for accessing XML or HTML structured documents.
913Native support for DOM in Gnome is on the way (module gnome-dom), and it will
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]914be based on gnome-xml. This will be a far cleaner interface to manipulate XML
Daniel Veillardc08a2c61999-09-08 21:35:25 +0000[diff] [blame]915files within Gnome since it won't expose the internal structure. DOM defines a
Daniel Veillard25940b71998-10-29 05:51:30 +0000[diff] [blame]916set of IDL (or Java) interfaces allowing to traverse and manipulate a
917document. The DOM library will allow accessing and modifying "live" documents
918presents on other programs like this:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]919
920<p><img src="DOM.gif" alt=" DOM.gif "></p>
921
922<p>This should help greatly doing things like modifying a gnumeric spreadsheet
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]923embedded in a GWP document for example.</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]924
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]925<p>The current DOM implementation on top of libxml is the <a
926href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is
927a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph
928Levien</a>.</p>
929
930<p>The gnome-dom module in the Gnome CVS base is obsolete</p>
931
Daniel Veillard35008381999-10-25 13:15:52 +0000[diff] [blame]932<h2><a name="Example"></a><a name="real">A real example</a></h2>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]933
934<p>Here is a real size example, where the actual content of the application
935data 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]936a proposal to keep a database of jobs related to Gnome, with an XML based
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]937storage structure. Here is an <a href="gjobs.xml">XML encoded jobs
938base</a>:</p>
939<pre>&lt;?xml version="1.0"?>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]940&lt;gjob:Helping xmlns:gjob="http://www.gnome.org/some-location">
941 &lt;gjob:Jobs>
942
943 &lt;gjob:Job>
944 &lt;gjob:Project ID="3"/>
945 &lt;gjob:Application>GBackup&lt;/gjob:Application>
946 &lt;gjob:Category>Development&lt;/gjob:Category>
947
948 &lt;gjob:Update>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]949 &lt;gjob:Status>Open&lt;/gjob:Status>
950 &lt;gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST&lt;/gjob:Modified>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]951 &lt;gjob:Salary>USD 0.00&lt;/gjob:Salary>
952 &lt;/gjob:Update>
953
954 &lt;gjob:Developers>
955 &lt;gjob:Developer>
956 &lt;/gjob:Developer>
957 &lt;/gjob:Developers>
958
959 &lt;gjob:Contact>
960 &lt;gjob:Person>Nathan Clemons&lt;/gjob:Person>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]961 &lt;gjob:Email>nathan@windsofstorm.net&lt;/gjob:Email>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]962 &lt;gjob:Company>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]963 &lt;/gjob:Company>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]964 &lt;gjob:Organisation>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]965 &lt;/gjob:Organisation>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]966 &lt;gjob:Webpage>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]967 &lt;/gjob:Webpage>
968 &lt;gjob:Snailmail>
969 &lt;/gjob:Snailmail>
970 &lt;gjob:Phone>
971 &lt;/gjob:Phone>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]972 &lt;/gjob:Contact>
973
974 &lt;gjob:Requirements>
975 The program should be released as free software, under the GPL.
976 &lt;/gjob:Requirements>
977
978 &lt;gjob:Skills>
979 &lt;/gjob:Skills>
980
981 &lt;gjob:Details>
982 A GNOME based system that will allow a superuser to configure
983 compressed and uncompressed files and/or file systems to be backed
984 up with a supported media in the system. This should be able to
985 perform via find commands generating a list of files that are passed
986 to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine
987 or via operations performed on the filesystem itself. Email
988 notification and GUI status display very important.
989 &lt;/gjob:Details>
990
991 &lt;/gjob:Job>
992
993 &lt;/gjob:Jobs>
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]994&lt;/gjob:Helping></pre>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]995
996<p>While loading the XML file into an internal DOM tree is a matter of calling
997only a couple of functions, browsing the tree to gather the informations and
998generate the internals structures is harder, and more error prone.</p>
999
1000<p>The suggested principle is to be tolerant with respect to the input
Daniel Veillardf13e1ed2000-03-06 07:41:49 +0000[diff] [blame]1001structure. For example, the ordering of the attributes is not significant,
1002Cthe XML specification is clear about it. It's also usually a good idea to not
1003be dependent of the orders of the childs of a given node, unless it really
1004makes things harder. Here is some code to parse the informations for a
1005person:</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1006<pre>/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1007 * A person record
1008 */
1009typedef struct person {
1010 char *name;
1011 char *email;
1012 char *company;
1013 char *organisation;
1014 char *smail;
1015 char *webPage;
1016 char *phone;
1017} person, *personPtr;
1018
1019/*
1020 * And the code needed to parse it
1021 */
1022personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1023 personPtr ret = NULL;
1024
1025DEBUG("parsePerson\n");
1026 /*
1027 * allocate the struct
1028 */
1029 ret = (personPtr) malloc(sizeof(person));
1030 if (ret == NULL) {
1031 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1032 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1033 }
1034 memset(ret, 0, sizeof(person));
1035
1036 /* We don't care what the top level element name is */
1037 cur = cur->childs;
1038 while (cur != NULL) {
1039 if ((!strcmp(cur->name, "Person")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1040 ret->name = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1041 if ((!strcmp(cur->name, "Email")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1042 ret->email = xmlNodeListGetString(doc, cur->childs, 1);
1043 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1044 }
1045
1046 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1047}</pre>
1048
1049<p>Here is a couple of things to notice:</p>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1050<ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1051 <li>Usually a recursive parsing style is the more convenient one, XML data
1052 being by nature subject to repetitive constructs and usualy exibit highly
1053 stuctured patterns.</li>
1054 <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e.
1055 the pointer to the global XML document and the namespace reserved to the
1056 application. Document wide information are needed for example to decode
1057 entities and it's a good coding practice to define a namespace for your
1058 application set of data and test that the element and attributes you're
1059 analyzing actually pertains to your application space. This is done by a
1060 simple equality test (cur->ns == ns).</li>
1061 <li>To retrieve text and attributes value, it is suggested to use the
1062 function <em>xmlNodeListGetString</em> to gather all the text and entity
1063 reference nodes generated by the DOM output and produce an single text
1064 string.</li>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1065</ul>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1066
1067<p>Here is another piece of code used to parse another level of the
1068structure:</p>
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]1069<pre>#include &lt;libxml/tree.h>
1070/*
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1071 * a Description for a Job
1072 */
1073typedef struct job {
1074 char *projectID;
1075 char *application;
1076 char *category;
1077 personPtr contact;
1078 int nbDevelopers;
1079 personPtr developers[100]; /* using dynamic alloc is left as an exercise */
1080} job, *jobPtr;
1081
1082/*
1083 * And the code needed to parse it
1084 */
1085jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) {
1086 jobPtr ret = NULL;
1087
1088DEBUG("parseJob\n");
1089 /*
1090 * allocate the struct
1091 */
1092 ret = (jobPtr) malloc(sizeof(job));
1093 if (ret == NULL) {
1094 fprintf(stderr,"out of memory\n");
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1095 return(NULL);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1096 }
1097 memset(ret, 0, sizeof(job));
1098
1099 /* We don't care what the top level element name is */
1100 cur = cur->childs;
1101 while (cur != NULL) {
1102
1103 if ((!strcmp(cur->name, "Project")) &amp;&amp; (cur->ns == ns)) {
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1104 ret->projectID = xmlGetProp(cur, "ID");
1105 if (ret->projectID == NULL) {
1106 fprintf(stderr, "Project has no ID\n");
1107 }
1108 }
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1109 if ((!strcmp(cur->name, "Application")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1110 ret->application = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1111 if ((!strcmp(cur->name, "Category")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1112 ret->category = xmlNodeListGetString(doc, cur->childs, 1);
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1113 if ((!strcmp(cur->name, "Contact")) &amp;&amp; (cur->ns == ns))
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1114 ret->contact = parsePerson(doc, ns, cur);
1115 cur = cur->next;
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1116 }
1117
1118 return(ret);
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1119}</pre>
Daniel Veillard14fff061999-06-22 21:49:07 +0000[diff] [blame]1120
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1121<p>One can notice that once used to it, writing this kind of code is quite
1122simple, but boring. Ultimately, it could be possble to write stubbers taking
1123either C data structure definitions, a set of XML examples or an XML DTD and
1124produce the code needed to import and export the content between C data and
1125XML storage. This is left as an exercise to the reader :-)</p>
1126
1127<p>Feel free to use <a href="gjobread.c">the code for the full C parsing
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1128example</a> as a template, it is also available with Makefile in the Gnome CVS
1129base under gnome-xml/example</p>
Daniel Veillardb05deb71999-08-10 19:04:08 +0000[diff] [blame]1130
Daniel Veillardc8eab3a1999-09-04 18:27:23 +0000[diff] [blame]1131<p></p>
1132
1133<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
1134
Daniel Veillard361d8452000-04-03 19:48:13 +0000[diff] [blame^]1135<p>$Id: xml.html,v 1.31 2000/03/24 13:41:54 veillard Exp $</p>
Daniel Veillardccb09631998-10-27 06:21:04 +0000[diff] [blame]1136</body>
1137</html>