Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 2 | "http://www.w3.org/TR/REC-html40/loose.dtd"> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 3 | <html> |
| 4 | <head> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 5 | <title>The XML library for Gnome</title> |
Daniel Veillard | b24054a | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 6 | <meta name="GENERATOR" content="amaya V2.4"> |
| 7 | <meta http-equiv="Content-Type" content="text/html"> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 8 | </head> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 9 | |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 10 | <body bgcolor="#ffffff"> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 11 | <h1 align="center">The XML library for Gnome</h1> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 12 | |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 13 | <h2 style="text-align: center">libxml, a.k.a. gnome-xml</h2> |
| 14 | |
| 15 | <p></p> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 16 | <ul> |
| 17 | <li><a href="#Introducti">Introduction</a></li> |
| 18 | <li><a href="#Documentat">Documentation</a></li> |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 19 | <li><a href="#Downloads">Downloads</a></li> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 20 | <li><a href="#News">News</a></li> |
| 21 | <li><a href="#XML">XML</a></li> |
| 22 | <li><a href="#tree">The tree output</a></li> |
| 23 | <li><a href="#interface">The SAX interface</a></li> |
| 24 | <li><a href="#library">The XML library interfaces</a> |
| 25 | <ul> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 26 | <li><a href="#Invoking">Invoking the parser: the pull way</a></li> |
| 27 | <li><a href="#Invoking">Invoking the parser: the push way</a></li> |
| 28 | <li><a href="#Invoking2">Invoking the parser: the SAX interface</a></li> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 29 | <li><a href="#Building">Building a tree from scratch</a></li> |
| 30 | <li><a href="#Traversing">Traversing the tree</a></li> |
| 31 | <li><a href="#Modifying">Modifying the tree</a></li> |
| 32 | <li><a href="#Saving">Saving the tree</a></li> |
| 33 | <li><a href="#Compressio">Compression</a></li> |
| 34 | </ul> |
| 35 | </li> |
| 36 | <li><a href="#Entities">Entities or no entities</a></li> |
| 37 | <li><a href="#Namespaces">Namespaces</a></li> |
| 38 | <li><a href="#Validation">Validation</a></li> |
| 39 | <li><a href="#Principles">DOM principles</a></li> |
| 40 | <li><a href="#real">A real example</a></li> |
| 41 | </ul> |
| 42 | |
| 43 | <h2><a name="Introducti">Introduction</a></h2> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 44 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 45 | <p>This document describes libxml, the <a href="http://www.w3.org/XML/">XML</a> |
| 46 | library provided in the <a href="http://www.gnome.org/">Gnome</a> framework. |
| 47 | XML is a standard for building tag-based structured documents/data.</p> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 48 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 49 | <p>Here are some key points about libxml:</p> |
| 50 | <ul> |
| 51 | <li>The internal document repesentation is as close as possible to the <a |
| 52 | href="http://www.w3.org/DOM/">DOM</a> interfaces.</li> |
| 53 | <li>Libxml also has a <a href="http://www.megginson.com/SAX/index.html">SAX |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 54 | like interface</a>; the interface is designed to be compatible with <a |
| 55 | href="http://www.jclark.com/xml/expat.html">Expat</a>.</li> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 56 | <li>Libxml now include a nearly complete <a |
| 57 | href="http://www.w3.org/TR/xpath">XPath</a> implementation.</li> |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 58 | <li>Libxml exports Push and Pull type parser interfaces for both XML and |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 59 | HTML.</li> |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 60 | <li>This library is released both under the W3C Copyright and the GNU LGPL. |
| 61 | Basically, everybody should be happy; if not, drop me a mail.</li> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 62 | </ul> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 63 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 64 | <h2><a name="Documentat">Documentation</a></h2> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 65 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 66 | <p>There are some on-line resources about using libxml:</p> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 67 | <ol> |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 68 | <li>The code is commented in a way which allows <a |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 69 | href="http://xmlsoft.org/libxml.html">extensive documentation</a> to be |
| 70 | automatically extracted.</li> |
| 71 | <li>This page provides a global overview and <a href="#real">some |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 72 | examples</a> on how to use libxml.</li> |
| 73 | <li><a href="mailto:james@daa.com.au">James Henstridge</a> wrote <a |
| 74 | href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice |
| 75 | documentation</a> explaining how to use the libxml SAX interface.</li> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 76 | <li>George Lebl wrote <a |
| 77 | href="http://www-4.ibm.com/software/developer/library/gnome3/">an article |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 78 | for IBM developerWorks</a> about using libxml.</li> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 79 | <li>It is also a good idea to check to <a href="mailto:raph@levien.com">Raph |
| 80 | Levien</a> <a href="http://levien.com/gnome/">web site</a> since he is |
| 81 | building the <a href="http://levien.com/gnome/gdome.html">DOM interface |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 82 | gdome</a> on top of libxml result tree and an implementation of <a |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 83 | href="http://www.w3.org/Graphics/SVG/">SVG</a> called <a |
| 84 | href="http://www.levien.com/svg/">gill</a>. Check his <a |
| 85 | href="http://www.levien.com/gnome/domination.html">DOMination |
| 86 | paper</a>.</li> |
| 87 | <li>And don't forget to look at the <a href="/messages/">mailing-list |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 88 | archive</a>, too.</li> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 89 | </ol> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 90 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 91 | <h3>Reporting bugs and getting help</h3> |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 92 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 93 | <p>Well, bugs or missing features are always possible, and I will make a point |
| 94 | of fixing them in a timely fashion. The best way to report a bug is to <a |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 95 | href="http://bugs.gnome.org/db/pa/lgnome-xml.html">use the Gnome bug tracking |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 96 | database</a>. I look at reports there regularly and it's good to have a |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 97 | reminder when a bug is still open. Check the <a |
| 98 | href="http://bugs.gnome.org/Reporting.html">instructions on reporting bugs</a> |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 99 | and be sure to specify that the bug is for the package gnome-xml.</p> |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 100 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 101 | <p>There is also a mailing-list <a |
| 102 | href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> for libxml, with an <a |
| 103 | href="http://xmlsoft.org/messages">on-line archive</a>. To subscribe to this |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 104 | majordomo based list, send a mail message to <a |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 105 | href="mailto:majordomo@rufus.w3.org">majordomo@rufus.w3.org</a> with |
| 106 | "subscribe xml" in the <strong>content</strong> of the message.</p> |
| 107 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 108 | <p>Alternatively, you can just send the bug to the <a |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 109 | href="mailto:xml@rufus.w3.org">xml@rufus.w3.org</a> list.</p> |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 110 | |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 111 | <h2><a name="Downloads">Downloads</a></h2> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 112 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 113 | <p>Latest versions can be found on <a |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 114 | href="ftp://rpmfind.net/pub/veillard/">rpmfind.net</a> or on the <a |
| 115 | href="ftp://ftp.gnome.org/pub/GNOME/MIRRORS.html">Gnome FTP server</a> either |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 116 | as a <a href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">source |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 117 | archive</a> or <a href="ftp://ftp.gnome.org/pub/GNOME/contrib/rpms/">RPMs |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 118 | packages</a> (NOTE that you need both the <a |
| 119 | href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a |
| 120 | href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a> |
| 121 | packages installed to compile applications using libxml).</p> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 122 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 123 | <p>Libxml is also available from 2 CVS bases:</p> |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 124 | <ul> |
| 125 | <li><p>The <a href="http://dev.w3.org/cvsweb/XML/">W3C CVS base</a>, |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 126 | available read-only using the CVS pserver authentification (I tend to use |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 127 | this base for my own development, so it's updated more regularly, but |
| 128 | the content may not be as stable):</p> |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 129 | <pre>CVSROOT=:pserver:anonymous@dev.w3.org:/sources/public |
| 130 | password: anonymous |
| 131 | module: XML</pre> |
| 132 | </li> |
| 133 | <li><p>The <a |
| 134 | href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&dir=gnome-xml">Gnome |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 135 | CVS base</a>. Check the <a |
| 136 | href="http://developer.gnome.org/tools/cvs.html">Gnome CVS Tools</a> page; |
| 137 | the CVS module is <b>gnome-xml</b>.</p> |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 138 | </li> |
| 139 | </ul> |
| 140 | |
| 141 | <h2><a name="News">News</a></h2> |
| 142 | |
Daniel Veillard | 944b5ff | 1999-12-15 19:08:24 +0000 | [diff] [blame] | 143 | <h3>CVS only : check the <a |
| 144 | href="http://cvs.gnome.org/lxr/source/gnome-xml/ChangeLog">Changelog</a> file |
| 145 | for really accurate description</h3> |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 146 | <ul> |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 147 | <li>working on HTML and XML links recognition layers, get in touch with me |
Daniel Veillard | 944b5ff | 1999-12-15 19:08:24 +0000 | [diff] [blame] | 148 | if you want to test those.</li> |
Daniel Veillard | da07c34 | 2000-01-25 18:31:22 +0000 | [diff] [blame] | 149 | <li>there is some kind of roadmap to libxml-2.0: fix I18N, and <a |
| 150 | href="http://rpmfind.net/tools/gdome/messages/0039.html">change structures |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 151 | to accommodate DOM</a></li> |
Daniel Veillard | e41f2b7 | 2000-01-30 20:00:07 +0000 | [diff] [blame] | 152 | </ul> |
| 153 | |
| 154 | <h3>1.8.6: Jan 31 2000</h3> |
| 155 | <ul> |
| 156 | <li>added a nanoFTP transport module, debugged until the new version of <a |
| 157 | href="http://rpmfind.net/linux/rpm2html/rpmfind.html">rpmfind</a> can use |
| 158 | it without troubles</li> |
Daniel Veillard | da07c34 | 2000-01-25 18:31:22 +0000 | [diff] [blame] | 159 | </ul> |
| 160 | |
| 161 | <h3>1.8.5: Jan 21 2000</h3> |
| 162 | <ul> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 163 | <li>adding APIs to parse a well balanced chunk of XML (production <a |
| 164 | href="http://www.w3.org/TR/REC-xml#NT-content">[43] content</a> of the XML |
| 165 | spec)</li> |
Daniel Veillard | 461a66c | 2000-01-18 18:01:01 +0000 | [diff] [blame] | 166 | <li>fixed a hideous bug in xmlGetProp pointed by Rune.Djurhuus@fast.no</li> |
| 167 | <li>Jody Goldberg <jgoldberg@home.com> provided another patch trying to |
| 168 | solve the zlib checks problems</li> |
| 169 | <li>The current state in gnome CVS base is expected to ship as 1.8.5 with |
| 170 | gnumeric soon</li> |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 171 | </ul> |
| 172 | |
| 173 | <h3>1.8.4: Jan 13 2000</h3> |
| 174 | <ul> |
| 175 | <li>bug fixes, reintroduced xmlNewGlobalNs(), fixed xmlNewNs()</li> |
| 176 | <li>all exit() call should have been removed from libxml</li> |
| 177 | <li>fixed a problem with INCLUDE_WINSOCK on WIN32 platform</li> |
| 178 | <li>added newDocFragment()</li> |
Daniel Veillard | f84f71f | 2000-01-05 19:54:23 +0000 | [diff] [blame] | 179 | </ul> |
| 180 | |
| 181 | <h3>1.8.3: Jan 5 2000</h3> |
| 182 | <ul> |
| 183 | <li>a Push interface for the XML and HTML parsers</li> |
Daniel Veillard | 437b87b | 2000-01-03 17:30:46 +0000 | [diff] [blame] | 184 | <li>an shell like interface to the document tree (try tester --shell |
| 185 | :-)</li> |
Daniel Veillard | dbfd641 | 1999-12-28 16:35:14 +0000 | [diff] [blame] | 186 | <li>lots of bug fixes and improvement added over XMas hollidays</li> |
Daniel Veillard | 437b87b | 2000-01-03 17:30:46 +0000 | [diff] [blame] | 187 | <li>fixed the DTD parsing code to work with the xhtml DTD</li> |
Daniel Veillard | f84f71f | 2000-01-05 19:54:23 +0000 | [diff] [blame] | 188 | <li>added xmlRemoveProp(), xmlRemoveID() and xmlRemoveRef()</li> |
| 189 | <li>Fixed bugs in xmlNewNs()</li> |
Daniel Veillard | 437b87b | 2000-01-03 17:30:46 +0000 | [diff] [blame] | 190 | <li>External entity loading code has been revamped, now it uses |
Daniel Veillard | f84f71f | 2000-01-05 19:54:23 +0000 | [diff] [blame] | 191 | xmlLoadExternalEntity(), some fix on entities processing were added</li> |
Daniel Veillard | 437b87b | 2000-01-03 17:30:46 +0000 | [diff] [blame] | 192 | <li>cleaned up WIN32 includes of socket stuff</li> |
Daniel Veillard | 5cb5ab8 | 1999-12-21 15:35:29 +0000 | [diff] [blame] | 193 | </ul> |
| 194 | |
| 195 | <h3>1.8.2: Dec 21 1999</h3> |
| 196 | <ul> |
Daniel Veillard | b24054a | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 197 | <li>I got another problem with includes and C++, I hope this issue is fixed |
| 198 | for good this time</li> |
Daniel Veillard | 5cb5ab8 | 1999-12-21 15:35:29 +0000 | [diff] [blame] | 199 | <li>Added a few tree modification functions: xmlReplaceNode, |
| 200 | xmlAddPrevSibling, xmlAddNextSibling, xmlNodeSetName and |
| 201 | xmlDocSetRootElement</li> |
| 202 | <li>Tried to improve the HTML output with help from <a |
| 203 | href="mailto:clahey@umich.edu">Chris Lahey</a></li> |
Daniel Veillard | e4e5131 | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 204 | </ul> |
Daniel Veillard | b24054a | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 205 | |
Daniel Veillard | e4e5131 | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 206 | <h3>1.8.1: Dec 18 1999</h3> |
| 207 | <ul> |
| 208 | <li>various patches to avoid troubles when using libxml with C++ compilers |
| 209 | the "namespace" keyword and C escaping in include files</li> |
| 210 | <li>a problem in one of the core macros IS_CHAR was corrected</li> |
| 211 | <li>fixed a bug introduced in 1.8.0 breaking default namespace processing, |
| 212 | and more specifically the Dia application</li> |
Daniel Veillard | 944b5ff | 1999-12-15 19:08:24 +0000 | [diff] [blame] | 213 | <li>fixed a posteriori validation (validation after parsing, or by using a |
| 214 | Dtd not specified in the original document)</li> |
Daniel Veillard | b24054a | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 215 | <li>fixed a bug in</li> |
Daniel Veillard | 10a2c65 | 1999-12-12 13:03:50 +0000 | [diff] [blame] | 216 | </ul> |
| 217 | |
| 218 | <h3>1.8.0: Dec 12 1999</h3> |
| 219 | <ul> |
| 220 | <li>cleanup, especially memory wise</li> |
| 221 | <li>the parser should be more reliable, especially the HTML one, it should |
| 222 | not crash, whatever the input !</li> |
| 223 | <li>Integrated various patches, especially a speedup improvement for large |
| 224 | dataset from <a href="mailto:cnygard@bellatlantic.net">Carl Nygard</a>, |
| 225 | configure with --with-buffers to enable them.</li> |
| 226 | <li>attribute normalization, oops should have been added long ago !</li> |
| 227 | <li>attributes defaulted from Dtds should be available, xmlSetProp() now |
| 228 | does entities escapting by default.</li> |
Daniel Veillard | 4c3a203 | 1999-11-19 17:46:26 +0000 | [diff] [blame] | 229 | </ul> |
Daniel Veillard | 3500838 | 1999-10-25 13:15:52 +0000 | [diff] [blame] | 230 | |
| 231 | <h3>1.7.4: Oct 25 1999</h3> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 232 | <ul> |
Daniel Veillard | 3500838 | 1999-10-25 13:15:52 +0000 | [diff] [blame] | 233 | <li>Lots of HTML improvement</li> |
| 234 | <li>Fixed some errors when saving both XML and HTML</li> |
| 235 | <li>More examples, the regression tests should now look clean</li> |
| 236 | <li>Fixed a bug with contiguous charref</li> |
| 237 | </ul> |
| 238 | |
| 239 | <h3>1.7.3: Sep 29 1999</h3> |
| 240 | <ul> |
| 241 | <li>portability problems fixed</li> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 242 | <li>snprintf was used unconditionnally, leading to link problems on system |
Daniel Veillard | 3500838 | 1999-10-25 13:15:52 +0000 | [diff] [blame] | 243 | were it's not available, fixed</li> |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 244 | </ul> |
| 245 | |
| 246 | <h3>1.7.1: Sep 24 1999</h3> |
| 247 | <ul> |
| 248 | <li>The basic type for strings manipulated by libxml has been renamed in |
| 249 | 1.7.1 from <strong>CHAR</strong> to <strong>xmlChar</strong>. The reason |
| 250 | is that CHAR was conflicting with a predefined type on Windows. However on |
| 251 | non WIN32 environment, compatibility is provided by the way of a |
| 252 | <strong>#define </strong>.</li> |
| 253 | <li>Changed another error : the use of a structure field called errno, and |
| 254 | leading to troubles on platforms where it's a macro</li> |
| 255 | </ul> |
| 256 | |
| 257 | <h3>1.7.0: sep 23 1999</h3> |
| 258 | <ul> |
| 259 | <li>Added the ability to fetch remote DTD or parsed entities, see the <a |
| 260 | href="gnome-xml-nanohttp.html">nanohttp</a> module.</li> |
| 261 | <li>Added an errno to report errors by another mean than a simple printf |
| 262 | like callback</li> |
| 263 | <li>Finished ID/IDREF support and checking when validation</li> |
| 264 | <li>Serious memory leaks fixed (there is now a <a |
| 265 | href="gnome-xml-xmlmemory.html">memory wrapper</a> module)</li> |
| 266 | <li>Improvement of <a href="http://www.w3.org/TR/xpath">XPath</a> |
| 267 | implementation</li> |
| 268 | <li>Added an HTML parser front-end</li> |
| 269 | </ul> |
| 270 | |
| 271 | <h2><a name="XML">XML</a></h2> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 272 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 273 | <p><a href="http://www.w3.org/TR/REC-xml">XML is a standard</a> for |
| 274 | markup-based structured documents. Here is <a name="example">an example |
| 275 | XML document</a>:</p> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 276 | <pre><?xml version="1.0"?> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 277 | <EXAMPLE prop1="gnome is great" prop2="&amp; linux too"> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 278 | <head> |
| 279 | <title>Welcome to Gnome</title> |
| 280 | </head> |
| 281 | <chapter> |
| 282 | <title>The Linux adventure</title> |
| 283 | <p>bla bla bla ...</p> |
| 284 | <image href="linus.gif"/> |
| 285 | <p>...</p> |
| 286 | </chapter> |
| 287 | </EXAMPLE></pre> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 288 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 289 | <p>The first line specifies that it's an XML document and gives useful |
| 290 | information about its encoding. Then the document is a text format whose |
| 291 | structure is specified by tags between brackets. <strong>Each tag opened has |
| 292 | to be closed</strong>. XML is pedantic about this. However, if a tag is |
| 293 | empty (no content), a single tag can serve as both the opening and closing |
| 294 | tag if it ends with <code>/></code> rather than with <code>></code>. |
| 295 | Note that, for example, the |
| 296 | image tag has no content (just an attribute) and is closed by ending the |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 297 | tag with <code>/></code>.</p> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 298 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 299 | <p>XML can be applied sucessfully to a wide range of uses, from long term |
| 300 | structured document maintenance (where it follows the steps of SGML) to simple |
| 301 | data encoding mechanisms like configuration file formatting (glade), spreadsheets |
| 302 | (gnumeric), or even shorter lived documents such as WebDAV where it is used to |
| 303 | encode remote calls between a client and a server.</p> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 304 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 305 | <h2><a name="tree">The tree output</a></h2> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 306 | |
| 307 | <p>The parser returns a tree built during the document analysis. The value |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 308 | returned is an <strong>xmlDocPtr</strong> (i.e., a pointer to an |
| 309 | <strong>xmlDoc</strong> structure). This structure contains information such as |
| 310 | the file name, the document type, and a <strong>root</strong> pointer which |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 311 | is the root of the document (or more exactly the first child under the root |
| 312 | which is the document). The tree is made of <strong>xmlNode</strong>s, chained |
| 313 | in double linked lists of siblings and with childs<->parent relationship. |
| 314 | An xmlNode can also carry properties (a chain of xmlAttr structures). An |
| 315 | attribute may have a value which is a list of TEXT or ENTITY_REF nodes.</p> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 316 | |
| 317 | <p>Here is an example (erroneous w.r.t. the XML spec since there should be |
| 318 | only one ELEMENT under the root):</p> |
| 319 | |
| 320 | <p><img src="structure.gif" alt=" structure.gif "></p> |
| 321 | |
| 322 | <p>In the source package there is a small program (not installed by default) |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 323 | called <strong>tester</strong> which parses XML files given as argument and |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 324 | prints them back as parsed. This is useful to detect errors both in XML code |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 325 | and in the XML parser itself. It has an option <strong>--debug</strong> which |
| 326 | prints the actual in-memory structure of the document, here is the result with |
| 327 | the <a href="#example">example</a> given before:</p> |
| 328 | <pre>DOCUMENT |
| 329 | version=1.0 |
| 330 | standalone=true |
| 331 | ELEMENT EXAMPLE |
| 332 | ATTRIBUTE prop1 |
| 333 | TEXT |
| 334 | content=gnome is great |
| 335 | ATTRIBUTE prop2 |
| 336 | ENTITY_REF |
| 337 | TEXT |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 338 | content= linux too |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 339 | ELEMENT head |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 340 | ELEMENT title |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 341 | TEXT |
| 342 | content=Welcome to Gnome |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 343 | ELEMENT chapter |
| 344 | ELEMENT title |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 345 | TEXT |
| 346 | content=The Linux adventure |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 347 | ELEMENT p |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 348 | TEXT |
| 349 | content=bla bla bla ... |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 350 | ELEMENT image |
| 351 | ATTRIBUTE href |
| 352 | TEXT |
| 353 | content=linus.gif |
| 354 | ELEMENT p |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 355 | TEXT |
| 356 | content=...</pre> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 357 | |
| 358 | <p>This should be useful to learn the internal representation model.</p> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 359 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 360 | <h2><a name="interface">The SAX interface</a></h2> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 361 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 362 | <p>Sometimes the DOM tree output is just too large to fit reasonably into |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 363 | memory. In that case and if you don't expect to save back the XML document |
| 364 | loaded using libxml, it's better to use the SAX interface of libxml. SAX is a |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 365 | <strong>callback-based interface</strong> to the parser. Before parsing, the |
| 366 | application layer registers a customized set of callbacks which are called |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 367 | by the library as it progresses through the XML input.</p> |
| 368 | |
| 369 | <p>To get a more detailed step-by-step guidance on using the SAX interface of |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 370 | libxml, <a href="mailto:james@daa.com.au">James Henstridge</a> has written <a |
| 371 | href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">some nice |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 372 | documentation.</a></p> |
| 373 | |
| 374 | <p>You can debug the SAX behaviour by using the <strong>testSAX</strong> |
| 375 | program located in the gnome-xml module (it's usually not shipped in the |
| 376 | binary packages of libxml, but you can also find it in the tar source |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 377 | distribution). Here is the sequence of callbacks that would be reported by |
| 378 | testSAX when parsing the example given before:</p> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 379 | <pre>SAX.setDocumentLocator() |
| 380 | SAX.startDocument() |
| 381 | SAX.getEntity(amp) |
| 382 | SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp; linux too') |
| 383 | SAX.characters( , 3) |
| 384 | SAX.startElement(head) |
| 385 | SAX.characters( , 4) |
| 386 | SAX.startElement(title) |
| 387 | SAX.characters(Welcome to Gnome, 16) |
| 388 | SAX.endElement(title) |
| 389 | SAX.characters( , 3) |
| 390 | SAX.endElement(head) |
| 391 | SAX.characters( , 3) |
| 392 | SAX.startElement(chapter) |
| 393 | SAX.characters( , 4) |
| 394 | SAX.startElement(title) |
| 395 | SAX.characters(The Linux adventure, 19) |
| 396 | SAX.endElement(title) |
| 397 | SAX.characters( , 4) |
| 398 | SAX.startElement(p) |
| 399 | SAX.characters(bla bla bla ..., 15) |
| 400 | SAX.endElement(p) |
| 401 | SAX.characters( , 4) |
| 402 | SAX.startElement(image, href='linus.gif') |
| 403 | SAX.endElement(image) |
| 404 | SAX.characters( , 4) |
| 405 | SAX.startElement(p) |
| 406 | SAX.characters(..., 3) |
| 407 | SAX.endElement(p) |
| 408 | SAX.characters( , 3) |
| 409 | SAX.endElement(chapter) |
| 410 | SAX.characters( , 1) |
| 411 | SAX.endElement(EXAMPLE) |
| 412 | SAX.endDocument()</pre> |
| 413 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 414 | <p>Most of the other functionalities of libxml are based on the DOM |
| 415 | tree-building facility, so nearly everything up to the end of this document |
| 416 | presupposes the use of the standard DOM tree build. Note that the DOM tree |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 417 | itself is built by a set of registered default callbacks, without internal |
| 418 | specific interface.</p> |
| 419 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 420 | <h2><a name="library">The XML library interfaces</a></h2> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 421 | |
| 422 | <p>This section is directly intended to help programmers getting bootstrapped |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 423 | using the XML library from the C language. It doesn't intent to be extensive, |
| 424 | I hope the automatically generated docs will provide the completeness |
| 425 | required, but as a separated set of documents. The interfaces of the XML |
| 426 | library are by principle low level, there is nearly zero abstration. Those |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 427 | interested in a higher level API should <a href="#DOM">look at DOM</a>.</p> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 428 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 429 | <p>The <a href="gnome-xml-parser.html">parser interfaces for XML</a> are |
| 430 | separated from the <a href="gnome-xml-htmlparser.html">HTML parser ones</a>, |
| 431 | let's have a look at how it can be called:</p> |
| 432 | |
| 433 | <h3><a name="Invoking">Invoking the parser : the pull way</a></h3> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 434 | |
| 435 | <p>Usually, the first thing to do is to read an XML input, the parser accepts |
| 436 | to parse both memory mapped documents or direct files. The functions are |
| 437 | defined in "parser.h":</p> |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 438 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 439 | <dt><code>xmlDocPtr xmlParseMemory(char *buffer, int size);</code></dt> |
| 440 | <dd><p>parse a zero terminated string containing the document</p> |
| 441 | </dd> |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 442 | </dl> |
| 443 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 444 | <dt><code>xmlDocPtr xmlParseFile(const char *filename);</code></dt> |
| 445 | <dd><p>parse an XML document contained in a file (possibly compressed)</p> |
| 446 | </dd> |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 447 | </dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 448 | |
| 449 | <p>This returns a pointer to the document structure (or NULL in case of |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 450 | failure).</p> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 451 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 452 | <h3 id="Invoking1">Invoking the parser: the push way</h3> |
| 453 | |
| 454 | <p>In order for the application to keep the control when the document is been |
| 455 | fetched (common for GUI based programs) the libxml, as of version 1.8.3 |
| 456 | provides a push interface too, here are the interfaces:</p> |
| 457 | <pre>xmlParserCtxtPtr xmlCreatePushParserCtxt(xmlSAXHandlerPtr sax, |
| 458 | void *user_data, |
| 459 | const char *chunk, |
| 460 | int size, |
| 461 | const char *filename); |
| 462 | int xmlParseChunk (xmlParserCtxtPtr ctxt, |
| 463 | const char *chunk, |
| 464 | int size, |
| 465 | int terminate);</pre> |
| 466 | |
| 467 | <p>and here is a simple use example:</p> |
| 468 | <pre> FILE *f; |
| 469 | |
| 470 | f = fopen(filename, "r"); |
| 471 | if (f != NULL) { |
| 472 | int res, size = 1024; |
| 473 | char chars[1024]; |
| 474 | xmlParserCtxtPtr ctxt; |
| 475 | |
| 476 | res = fread(chars, 1, 4, f); |
| 477 | if (res > 0) { |
| 478 | ctxt = xmlCreatePushParserCtxt(NULL, NULL, |
| 479 | chars, res, filename); |
| 480 | while ((res = fread(chars, 1, size, f)) > 0) { |
| 481 | xmlParseChunk(ctxt, chars, res, 0); |
| 482 | } |
| 483 | xmlParseChunk(ctxt, chars, 0, 1); |
| 484 | doc = ctxt->myDoc; |
| 485 | xmlFreeParserCtxt(ctxt); |
| 486 | } |
| 487 | }</pre> |
| 488 | |
| 489 | <p>Also note that the HTML parser embedded into libxml also have a push |
| 490 | interface they are just prefixed by "html" instead of "xml"</p> |
| 491 | |
| 492 | <h3 id="Invoking2">Invoking the parser: the SAX interface</h3> |
| 493 | |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 494 | <p>A couple of comments can be made, first this mean that the parser is |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 495 | memory-hungry, first to load the document in memory, second to build the tree. |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 496 | Reading a document without building the tree is possible using the SAX |
| 497 | interfaces (see SAX.h and <a |
| 498 | href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">James |
| 499 | Henstridge documentation</a>), not also that the push interface can be limited |
| 500 | to SAX, just use the two first arguments of |
| 501 | <code>xmlCreatePushParserCtxt()</code>.</p> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 502 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 503 | <h3><a name="Building">Building a tree from scratch</a></h3> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 504 | |
| 505 | <p>The other way to get an XML tree in memory is by building it. Basically |
| 506 | there is a set of functions dedicated to building new elements, those are also |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 507 | described in "tree.h", here is for example the piece of code producing the |
| 508 | example used before:</p> |
| 509 | <pre> xmlDocPtr doc; |
| 510 | xmlNodePtr tree, subtree; |
| 511 | |
| 512 | doc = xmlNewDoc("1.0"); |
| 513 | doc->root = xmlNewDocNode(doc, NULL, "EXAMPLE", NULL); |
| 514 | xmlSetProp(doc->root, "prop1", "gnome is great"); |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 515 | xmlSetProp(doc->root, "prop2", "& linux too"); |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 516 | tree = xmlNewChild(doc->root, NULL, "head", NULL); |
| 517 | subtree = xmlNewChild(tree, NULL, "title", "Welcome to Gnome"); |
| 518 | tree = xmlNewChild(doc->root, NULL, "chapter", NULL); |
| 519 | subtree = xmlNewChild(tree, NULL, "title", "The Linux adventure"); |
| 520 | subtree = xmlNewChild(tree, NULL, "p", "bla bla bla ..."); |
| 521 | subtree = xmlNewChild(tree, NULL, "image", NULL); |
| 522 | xmlSetProp(subtree, "href", "linus.gif");</pre> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 523 | |
| 524 | <p>Not really rocket science ...</p> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 525 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 526 | <h3><a name="Traversing">Traversing the tree</a></h3> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 527 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 528 | <p>Basically by <a href="gnome-xml-tree.html">including "tree.h"</a> your code |
| 529 | has access to the internal structure of all the element of the tree. The names |
| 530 | should be somewhat simple like <strong>parent</strong>, |
| 531 | <strong>childs</strong>, <strong>next</strong>, <strong>prev</strong>, |
| 532 | <strong>properties</strong>, etc... For example still with the previous |
| 533 | example:</p> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 534 | <pre><code>doc->root->childs->childs</code></pre> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 535 | |
| 536 | <p>points to the title element,</p> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 537 | <pre>doc->root->childs->next->child->child</pre> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 538 | |
| 539 | <p>points to the text node containing the chapter titlle "The Linux adventure" |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 540 | and</p> |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 541 | |
Daniel Veillard | b24054a | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 542 | <p><strong>NOTE</strong>: XML allows <em>PI</em>s and <em>comments</em> to be |
| 543 | present before the document root, so doc->root may point to an element which |
| 544 | is not the document Root Element, a function |
Daniel Veillard | 5cb5ab8 | 1999-12-21 15:35:29 +0000 | [diff] [blame] | 545 | <code>xmlDocGetRootElement()</code> was added for this purpose.</p> |
Daniel Veillard | b24054a | 1999-12-18 15:32:46 +0000 | [diff] [blame] | 546 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 547 | <h3><a name="Modifying">Modifying the tree</a></h3> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 548 | |
Daniel Veillard | 0142b84 | 2000-01-14 14:45:24 +0000 | [diff] [blame] | 549 | <p>functions are provided to read and write the document content, here is an |
| 550 | excerpt from the <a href="gnome-xml-tree.html">tree API</a>:</p> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 551 | <dl> |
Daniel Veillard | dd6b367 | 1999-09-23 22:19:22 +0000 | [diff] [blame] | 552 | <dt><code>xmlAttrPtr xmlSetProp(xmlNodePtr node, const xmlChar *name, const |
| 553 | xmlChar *value);</code></dt> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 554 | <dd><p>This set (or change) an attribute carried by an ELEMENT node the |
| 555 | value can be NULL</p> |
| 556 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 557 | </dl> |
| 558 | <dl> |
Daniel Veillard | dd6b367 | 1999-09-23 22:19:22 +0000 | [diff] [blame] | 559 | <dt><code>const xmlChar *xmlGetProp(xmlNodePtr node, const xmlChar |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 560 | *name);</code></dt> |
| 561 | <dd><p>This function returns a pointer to the property content, note that |
| 562 | no extra copy is made</p> |
| 563 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 564 | </dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 565 | |
| 566 | <p>Two functions must be used to read an write the text associated to |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 567 | elements:</p> |
| 568 | <dl> |
Daniel Veillard | dd6b367 | 1999-09-23 22:19:22 +0000 | [diff] [blame] | 569 | <dt><code>xmlNodePtr xmlStringGetNodeList(xmlDocPtr doc, const xmlChar |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 570 | *value);</code></dt> |
| 571 | <dd><p>This function takes an "external" string and convert it to one text |
| 572 | node or possibly to a list of entity and text nodes. All non-predefined |
| 573 | entity references like &Gnome; will be stored internally as an |
| 574 | entity node, hence the result of the function may not be a single |
| 575 | node.</p> |
| 576 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 577 | </dl> |
| 578 | <dl> |
Daniel Veillard | dd6b367 | 1999-09-23 22:19:22 +0000 | [diff] [blame] | 579 | <dt><code>xmlChar *xmlNodeListGetString(xmlDocPtr doc, xmlNodePtr list, int |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 580 | inLine);</code></dt> |
| 581 | <dd><p>this is the dual function, which generate a new string containing |
| 582 | the content of the text and entity nodes. Note the extra argument |
| 583 | inLine, if set to 1 instead of returning the &Gnome; XML encoding in |
| 584 | the string it will substitute it with it's value say "GNU Network Object |
| 585 | Model Environment". Set it if you want to use the string for non XML |
| 586 | usage like User Interface.</p> |
| 587 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 588 | </dl> |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 589 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 590 | <h3><a name="Saving">Saving a tree</a></h3> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 591 | |
| 592 | <p>Basically 3 options are possible:</p> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 593 | <dl> |
Daniel Veillard | dd6b367 | 1999-09-23 22:19:22 +0000 | [diff] [blame] | 594 | <dt><code>void xmlDocDumpMemory(xmlDocPtr cur, xmlChar**mem, int |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 595 | *size);</code></dt> |
| 596 | <dd><p>returns a buffer where the document has been saved</p> |
| 597 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 598 | </dl> |
| 599 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 600 | <dt><code>extern void xmlDocDump(FILE *f, xmlDocPtr doc);</code></dt> |
| 601 | <dd><p>dumps a buffer to an open file descriptor</p> |
| 602 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 603 | </dl> |
| 604 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 605 | <dt><code>int xmlSaveFile(const char *filename, xmlDocPtr cur);</code></dt> |
| 606 | <dd><p>save the document ot a file. In that case the compression interface |
| 607 | is triggered if turned on</p> |
| 608 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 609 | </dl> |
Daniel Veillard | 10c6a8f | 1998-10-28 01:00:12 +0000 | [diff] [blame] | 610 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 611 | <h3><a name="Compressio">Compression</a></h3> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 612 | |
| 613 | <p>The library handle transparently compression when doing file based |
| 614 | accesses, the level of compression on saves can be tuned either globally or |
| 615 | individually for one file:</p> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 616 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 617 | <dt><code>int xmlGetDocCompressMode (xmlDocPtr doc);</code></dt> |
| 618 | <dd><p>Get the document compression ratio (0-9)</p> |
| 619 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 620 | </dl> |
| 621 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 622 | <dt><code>void xmlSetDocCompressMode (xmlDocPtr doc, int mode);</code></dt> |
| 623 | <dd><p>Set the document compression ratio</p> |
| 624 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 625 | </dl> |
| 626 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 627 | <dt><code>int xmlGetCompressMode(void);</code></dt> |
| 628 | <dd><p>Get the default compression ratio</p> |
| 629 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 630 | </dl> |
| 631 | <dl> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 632 | <dt><code>void xmlSetCompressMode(int mode);</code></dt> |
| 633 | <dd><p>set the default compression ratio</p> |
| 634 | </dd> |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 635 | </dl> |
| 636 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 637 | <h2><a name="Entities">Entities or no entities</a></h2> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 638 | |
| 639 | <p>Entities principle is similar to simple C macros. They define an |
| 640 | abbreviation for a given string that you can reuse many time through the |
| 641 | content of your document. They are especially useful when frequent occurrences |
| 642 | of a given string may occur within a document or to confine the change needed |
| 643 | to a document to a restricted area in the internal subset of the document (at |
| 644 | the beginning). Example:</p> |
| 645 | <pre>1 <?xml version="1.0"?> |
| 646 | 2 <!DOCTYPE EXAMPLE SYSTEM "example.dtd" [ |
| 647 | 3 <!ENTITY xml "Extensible Markup Language"> |
| 648 | 4 ]> |
| 649 | 5 <EXAMPLE> |
| 650 | 6 &xml; |
Daniel Veillard | 3500838 | 1999-10-25 13:15:52 +0000 | [diff] [blame] | 651 | 7 </EXAMPLE></pre> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 652 | |
| 653 | <p>Line 3 declares the xml entity. Line 6 uses the xml entity, by prefixing |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 654 | it's name with '&' and following it by ';' without any spaces added. There |
| 655 | are 5 predefined entities in libxml allowing to escape charaters with |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 656 | predefined meaning in some parts of the xml document content: |
| 657 | <strong>&lt;</strong> for the letter '<', <strong>&gt;</strong> for |
| 658 | the letter '>', <strong>&apos;</strong> for the letter ''', |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 659 | <strong>&quot;</strong> for the letter '"', and <strong>&amp;</strong> |
| 660 | for the letter '&'.</p> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 661 | |
| 662 | <p>One of the problems related to entities is that you may want the parser to |
| 663 | substitute entities content to see the replacement text in your application, |
| 664 | or you may prefer keeping entities references as such in the content to be |
| 665 | able to save the document back without loosing this usually precious |
| 666 | information (if the user went through the pain of explicitley defining |
| 667 | entities, he may have a a rather negative attitude if you blindly susbtitute |
| 668 | them as saving time). The function <a |
| 669 | href="gnome-xml-parser.html#XMLSUBSTITUTEENTITIESDEFAULT">xmlSubstituteEntitiesDefault()</a> |
| 670 | allows to check and change the behaviour, which is to not substitute entities |
| 671 | by default.</p> |
| 672 | |
| 673 | <p>Here is the DOM tree built by libxml for the previous document in the |
| 674 | default case:</p> |
| 675 | <pre>/gnome/src/gnome-xml -> ./tester --debug test/ent1 |
| 676 | DOCUMENT |
| 677 | version=1.0 |
| 678 | ELEMENT EXAMPLE |
| 679 | TEXT |
| 680 | content= |
| 681 | ENTITY_REF |
| 682 | INTERNAL_GENERAL_ENTITY xml |
| 683 | content=Extensible Markup Language |
| 684 | TEXT |
| 685 | content=</pre> |
| 686 | |
| 687 | <p>And here is the result when substituting entities:</p> |
| 688 | <pre>/gnome/src/gnome-xml -> ./tester --debug --noent test/ent1 |
| 689 | DOCUMENT |
| 690 | version=1.0 |
| 691 | ELEMENT EXAMPLE |
| 692 | TEXT |
| 693 | content= Extensible Markup Language</pre> |
| 694 | |
| 695 | <p>So entities or no entities ? Basically it depends on your use case, I |
| 696 | suggest to keep the non-substituting default behaviour and avoid using |
| 697 | entities in your XML document or data if you are not willing to handle the |
| 698 | entity references elements in the DOM tree.</p> |
| 699 | |
| 700 | <p>Note that at save time libxml enforce the conversion of the predefined |
| 701 | entities where necessary to prevent well-formedness problems, and will also |
| 702 | transparently replace those with chars (i.e. will not generate entity |
| 703 | reference elements in the DOM tree nor call the reference() SAX callback when |
| 704 | finding them in the input).</p> |
| 705 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 706 | <h2><a name="Namespaces">Namespaces</a></h2> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 707 | |
| 708 | <p>The libxml library implement namespace @@ support by recognizing namespace |
| 709 | contructs in the input, and does namespace lookup automatically when building |
| 710 | the DOM tree. A namespace declaration is associated with an in-memory |
| 711 | structure and all elements or attributes within that namespace point to it. |
| 712 | Hence testing the namespace is a simple and fast equality operation at the |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 713 | user level.</p> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 714 | |
| 715 | <p>I suggest it that people using libxml use a namespace, and declare it on |
| 716 | the root element of their document as the default namespace. Then they dont |
| 717 | need to happend the prefix in the content but we will have a basis for future |
| 718 | semantic refinement and merging of data from different sources. This doesn't |
| 719 | augment significantly the size of the XML output, but significantly increase |
| 720 | it's value in the long-term.</p> |
| 721 | |
| 722 | <p>Concerning the namespace value, this has to be an URL, but this doesn't |
| 723 | have to point to any existing resource on the Web. I suggest using an URL |
| 724 | within a domain you control, which makes sense and if possible holding some |
| 725 | kind of versionning informations. For example |
| 726 | <code>"http://www.gnome.org/gnumeric/1.0"</code> is a good namespace scheme. |
| 727 | Then when you load a file, make sure that a namespace carrying the |
| 728 | version-independant prefix is installed on the root element of your document, |
| 729 | and if the version information don't match something you know, warn the user |
| 730 | and be liberal in what you accept as the input. Also do *not* try to base |
| 731 | namespace checking on the prefix value <foo:text> may be exactly the same |
| 732 | as <bar:text> in another document, what really matter is the URI |
| 733 | associated with the element or the attribute, not the prefix string which is |
| 734 | just a shortcut for the full URI.</p> |
| 735 | |
| 736 | <p>@@Interfaces@@</p> |
| 737 | |
| 738 | <p>@@Examples@@</p> |
| 739 | |
| 740 | <p>Usually people object using namespace in the case of validation, I object |
| 741 | this and will make sure that using namespaces won't break validity checking, |
| 742 | so even is you plan or are using validation I strongly suggest to add |
| 743 | namespaces to your document. A default namespace scheme |
| 744 | <code>xmlns="http://...."</code> should not break validity even on less |
| 745 | flexible parsers. Now using namespace to mix and differenciate content coming |
| 746 | from mutliple Dtd will certainly break current validation schemes, I will try |
| 747 | to provide ways to do this, but this may not be portable or standardized.</p> |
| 748 | |
Daniel Veillard | 2f4dfc4 | 1999-09-24 14:03:48 +0000 | [diff] [blame] | 749 | <h2><a name="Validation">Validation, or are you afraid of DTDs ?</a></h2> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 750 | |
| 751 | <p>Well what is validation and what is a DTD ?</p> |
| 752 | |
| 753 | <p>Validation is the process of checking a document against a set of |
| 754 | construction rules, a <strong>DTD</strong> (Document Type Definition) is such |
| 755 | a set of rules.</p> |
| 756 | |
| 757 | <p>The validation process and building DTDs are the two most difficult parts |
| 758 | of XML life cycle. Briefly a DTD defines all the possibles element to be |
| 759 | found within your document, what is the formal shape of your document tree (by |
| 760 | defining the allowed content of an element, either text, a regular expression |
| 761 | for the allowed list of children, or mixed content i.e. both text and childs). |
| 762 | The DTD also defines the allowed attributes for all elements and the types of |
| 763 | the attributes. For more detailed informations, I suggest to read the related |
| 764 | parts of the XML specification, the examples found under |
| 765 | gnome-xml/test/valid/dtd and the large amount of books available on XML. The |
| 766 | dia example in gnome-xml/test/valid should be both simple and complete enough |
| 767 | to allow you to build your own.</p> |
| 768 | |
| 769 | <p>A word of warning, building a good DTD which will fit your needs of your |
| 770 | application in the long-term is far from trivial, however the extra level of |
| 771 | quality it can insure is well worth the price for some sets of applications or |
| 772 | if you already have already a DTD defined for your application field.</p> |
| 773 | |
| 774 | <p>The validation is not completely finished but in a (very IMHO) usable |
| 775 | state. Until a real validation interface is defined the way to do it is to |
| 776 | define and set the <strong>xmlDoValidityCheckingDefaultValue</strong> external |
| 777 | variable to 1, this will of course be changed at some point:</p> |
| 778 | |
| 779 | <p>extern int xmlDoValidityCheckingDefaultValue;</p> |
| 780 | |
| 781 | <p>...</p> |
| 782 | |
| 783 | <p>xmlDoValidityCheckingDefaultValue = 1;</p> |
| 784 | |
| 785 | <p></p> |
| 786 | |
| 787 | <p>To handle external entities, use the function |
| 788 | <strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to |
| 789 | link in you HTTP/FTP/Entities database library to the standard libxml |
| 790 | core.</p> |
| 791 | |
| 792 | <p>@@interfaces@@</p> |
| 793 | |
Daniel Veillard | 3500838 | 1999-10-25 13:15:52 +0000 | [diff] [blame] | 794 | <h2><a name="DOM"></a><a name="Principles">DOM Principles</a></h2> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 795 | |
| 796 | <p><a href="http://www.w3.org/DOM/">DOM</a> stands for the <em>Document Object |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 797 | Model</em> this is an API for accessing XML or HTML structured documents. |
| 798 | Native support for DOM in Gnome is on the way (module gnome-dom), and it will |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 799 | be based on gnome-xml. This will be a far cleaner interface to manipulate XML |
Daniel Veillard | c08a2c6 | 1999-09-08 21:35:25 +0000 | [diff] [blame] | 800 | files within Gnome since it won't expose the internal structure. DOM defines a |
Daniel Veillard | 25940b7 | 1998-10-29 05:51:30 +0000 | [diff] [blame] | 801 | set of IDL (or Java) interfaces allowing to traverse and manipulate a |
| 802 | document. The DOM library will allow accessing and modifying "live" documents |
| 803 | presents on other programs like this:</p> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 804 | |
| 805 | <p><img src="DOM.gif" alt=" DOM.gif "></p> |
| 806 | |
| 807 | <p>This should help greatly doing things like modifying a gnumeric spreadsheet |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 808 | embedded in a GWP document for example.</p> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 809 | |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 810 | <p>The current DOM implementation on top of libxml is the <a |
| 811 | href="http://cvs.gnome.org/lxr/source/gdome/">gdome Gnome module</a>, this is |
| 812 | a full DOM interface, thanks to <a href="mailto:raph@levien.com">Raph |
| 813 | Levien</a>.</p> |
| 814 | |
| 815 | <p>The gnome-dom module in the Gnome CVS base is obsolete</p> |
| 816 | |
Daniel Veillard | 3500838 | 1999-10-25 13:15:52 +0000 | [diff] [blame] | 817 | <h2><a name="Example"></a><a name="real">A real example</a></h2> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 818 | |
| 819 | <p>Here is a real size example, where the actual content of the application |
| 820 | data is not kept in the DOM tree but uses internal structures. It is based on |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 821 | a proposal to keep a database of jobs related to Gnome, with an XML based |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 822 | storage structure. Here is an <a href="gjobs.xml">XML encoded jobs |
| 823 | base</a>:</p> |
| 824 | <pre><?xml version="1.0"?> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 825 | <gjob:Helping xmlns:gjob="http://www.gnome.org/some-location"> |
| 826 | <gjob:Jobs> |
| 827 | |
| 828 | <gjob:Job> |
| 829 | <gjob:Project ID="3"/> |
| 830 | <gjob:Application>GBackup</gjob:Application> |
| 831 | <gjob:Category>Development</gjob:Category> |
| 832 | |
| 833 | <gjob:Update> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 834 | <gjob:Status>Open</gjob:Status> |
| 835 | <gjob:Modified>Mon, 07 Jun 1999 20:27:45 -0400 MET DST</gjob:Modified> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 836 | <gjob:Salary>USD 0.00</gjob:Salary> |
| 837 | </gjob:Update> |
| 838 | |
| 839 | <gjob:Developers> |
| 840 | <gjob:Developer> |
| 841 | </gjob:Developer> |
| 842 | </gjob:Developers> |
| 843 | |
| 844 | <gjob:Contact> |
| 845 | <gjob:Person>Nathan Clemons</gjob:Person> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 846 | <gjob:Email>nathan@windsofstorm.net</gjob:Email> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 847 | <gjob:Company> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 848 | </gjob:Company> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 849 | <gjob:Organisation> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 850 | </gjob:Organisation> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 851 | <gjob:Webpage> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 852 | </gjob:Webpage> |
| 853 | <gjob:Snailmail> |
| 854 | </gjob:Snailmail> |
| 855 | <gjob:Phone> |
| 856 | </gjob:Phone> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 857 | </gjob:Contact> |
| 858 | |
| 859 | <gjob:Requirements> |
| 860 | The program should be released as free software, under the GPL. |
| 861 | </gjob:Requirements> |
| 862 | |
| 863 | <gjob:Skills> |
| 864 | </gjob:Skills> |
| 865 | |
| 866 | <gjob:Details> |
| 867 | A GNOME based system that will allow a superuser to configure |
| 868 | compressed and uncompressed files and/or file systems to be backed |
| 869 | up with a supported media in the system. This should be able to |
| 870 | perform via find commands generating a list of files that are passed |
| 871 | to tar, dd, cpio, cp, gzip, etc., to be directed to the tape machine |
| 872 | or via operations performed on the filesystem itself. Email |
| 873 | notification and GUI status display very important. |
| 874 | </gjob:Details> |
| 875 | |
| 876 | </gjob:Job> |
| 877 | |
| 878 | </gjob:Jobs> |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 879 | </gjob:Helping></pre> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 880 | |
| 881 | <p>While loading the XML file into an internal DOM tree is a matter of calling |
| 882 | only a couple of functions, browsing the tree to gather the informations and |
| 883 | generate the internals structures is harder, and more error prone.</p> |
| 884 | |
| 885 | <p>The suggested principle is to be tolerant with respect to the input |
| 886 | structure. For example the ordering of the attributes is not significant, Cthe |
| 887 | XML specification is clear about it. It's also usually a good idea to not be |
| 888 | dependant of the orders of the childs of a given node, unless it really makes |
| 889 | things harder. Here is some code to parse the informations for a person:</p> |
| 890 | <pre>/* |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 891 | * A person record |
| 892 | */ |
| 893 | typedef struct person { |
| 894 | char *name; |
| 895 | char *email; |
| 896 | char *company; |
| 897 | char *organisation; |
| 898 | char *smail; |
| 899 | char *webPage; |
| 900 | char *phone; |
| 901 | } person, *personPtr; |
| 902 | |
| 903 | /* |
| 904 | * And the code needed to parse it |
| 905 | */ |
| 906 | personPtr parsePerson(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { |
| 907 | personPtr ret = NULL; |
| 908 | |
| 909 | DEBUG("parsePerson\n"); |
| 910 | /* |
| 911 | * allocate the struct |
| 912 | */ |
| 913 | ret = (personPtr) malloc(sizeof(person)); |
| 914 | if (ret == NULL) { |
| 915 | fprintf(stderr,"out of memory\n"); |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 916 | return(NULL); |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 917 | } |
| 918 | memset(ret, 0, sizeof(person)); |
| 919 | |
| 920 | /* We don't care what the top level element name is */ |
| 921 | cur = cur->childs; |
| 922 | while (cur != NULL) { |
| 923 | if ((!strcmp(cur->name, "Person")) && (cur->ns == ns)) |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 924 | ret->name = xmlNodeListGetString(doc, cur->childs, 1); |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 925 | if ((!strcmp(cur->name, "Email")) && (cur->ns == ns)) |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 926 | ret->email = xmlNodeListGetString(doc, cur->childs, 1); |
| 927 | cur = cur->next; |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 928 | } |
| 929 | |
| 930 | return(ret); |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 931 | }</pre> |
| 932 | |
| 933 | <p>Here is a couple of things to notice:</p> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 934 | <ul> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 935 | <li>Usually a recursive parsing style is the more convenient one, XML data |
| 936 | being by nature subject to repetitive constructs and usualy exibit highly |
| 937 | stuctured patterns.</li> |
| 938 | <li>The two arguments of type <em>xmlDocPtr</em> and <em>xmlNsPtr</em>, i.e. |
| 939 | the pointer to the global XML document and the namespace reserved to the |
| 940 | application. Document wide information are needed for example to decode |
| 941 | entities and it's a good coding practice to define a namespace for your |
| 942 | application set of data and test that the element and attributes you're |
| 943 | analyzing actually pertains to your application space. This is done by a |
| 944 | simple equality test (cur->ns == ns).</li> |
| 945 | <li>To retrieve text and attributes value, it is suggested to use the |
| 946 | function <em>xmlNodeListGetString</em> to gather all the text and entity |
| 947 | reference nodes generated by the DOM output and produce an single text |
| 948 | string.</li> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 949 | </ul> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 950 | |
| 951 | <p>Here is another piece of code used to parse another level of the |
| 952 | structure:</p> |
| 953 | <pre>/* |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 954 | * a Description for a Job |
| 955 | */ |
| 956 | typedef struct job { |
| 957 | char *projectID; |
| 958 | char *application; |
| 959 | char *category; |
| 960 | personPtr contact; |
| 961 | int nbDevelopers; |
| 962 | personPtr developers[100]; /* using dynamic alloc is left as an exercise */ |
| 963 | } job, *jobPtr; |
| 964 | |
| 965 | /* |
| 966 | * And the code needed to parse it |
| 967 | */ |
| 968 | jobPtr parseJob(xmlDocPtr doc, xmlNsPtr ns, xmlNodePtr cur) { |
| 969 | jobPtr ret = NULL; |
| 970 | |
| 971 | DEBUG("parseJob\n"); |
| 972 | /* |
| 973 | * allocate the struct |
| 974 | */ |
| 975 | ret = (jobPtr) malloc(sizeof(job)); |
| 976 | if (ret == NULL) { |
| 977 | fprintf(stderr,"out of memory\n"); |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 978 | return(NULL); |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 979 | } |
| 980 | memset(ret, 0, sizeof(job)); |
| 981 | |
| 982 | /* We don't care what the top level element name is */ |
| 983 | cur = cur->childs; |
| 984 | while (cur != NULL) { |
| 985 | |
| 986 | if ((!strcmp(cur->name, "Project")) && (cur->ns == ns)) { |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 987 | ret->projectID = xmlGetProp(cur, "ID"); |
| 988 | if (ret->projectID == NULL) { |
| 989 | fprintf(stderr, "Project has no ID\n"); |
| 990 | } |
| 991 | } |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 992 | if ((!strcmp(cur->name, "Application")) && (cur->ns == ns)) |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 993 | ret->application = xmlNodeListGetString(doc, cur->childs, 1); |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 994 | if ((!strcmp(cur->name, "Category")) && (cur->ns == ns)) |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 995 | ret->category = xmlNodeListGetString(doc, cur->childs, 1); |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 996 | if ((!strcmp(cur->name, "Contact")) && (cur->ns == ns)) |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 997 | ret->contact = parsePerson(doc, ns, cur); |
| 998 | cur = cur->next; |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 999 | } |
| 1000 | |
| 1001 | return(ret); |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 1002 | }</pre> |
Daniel Veillard | 14fff06 | 1999-06-22 21:49:07 +0000 | [diff] [blame] | 1003 | |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 1004 | <p>One can notice that once used to it, writing this kind of code is quite |
| 1005 | simple, but boring. Ultimately, it could be possble to write stubbers taking |
| 1006 | either C data structure definitions, a set of XML examples or an XML DTD and |
| 1007 | produce the code needed to import and export the content between C data and |
| 1008 | XML storage. This is left as an exercise to the reader :-)</p> |
| 1009 | |
| 1010 | <p>Feel free to use <a href="gjobread.c">the code for the full C parsing |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 1011 | example</a> as a template, it is also available with Makefile in the Gnome CVS |
| 1012 | base under gnome-xml/example</p> |
Daniel Veillard | b05deb7 | 1999-08-10 19:04:08 +0000 | [diff] [blame] | 1013 | |
Daniel Veillard | c8eab3a | 1999-09-04 18:27:23 +0000 | [diff] [blame] | 1014 | <p></p> |
| 1015 | |
| 1016 | <p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p> |
| 1017 | |
Daniel Veillard | 402e8c8 | 2000-02-29 22:57:47 +0000 | [diff] [blame^] | 1018 | <p>$Id: xml.html,v 1.24 2000/01/30 20:00:06 veillard Exp $</p> |
Daniel Veillard | ccb0963 | 1998-10-27 06:21:04 +0000 | [diff] [blame] | 1019 | </body> |
| 1020 | </html> |