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Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]5 <title>Libxml Frequently Asked Questions</title>
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Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]11<h1 align="center">Libxml Frequently Asked Questions</h1>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]12
13<p>Location: <a
14href="http://xmlsoft.org/FAQ.html">http://xmlsoft.org/FAQ.html</a></p>
15
16<p>Libxml home page: <a href="http://xmlsoft.org/">http://xmlsoft.org/</a></p>
17
18<p>Mailing-list archive: <a
19href="http://xmlsoft.org/messages/">http://xmlsoft.org/messages/</a></p>
20
Daniel Veillardbe40c8b2000-07-14 12:10:59 +0000[diff] [blame]21<p>Version: $Revision$</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]22
23<p>Table of Content:</p>
24<ul>
25 <li><a href="#Licence">Licence(s)</a></li>
26 <li><a href="#Installati">Installation</a></li>
27 <li><a href="#Compilatio">Compilation</a></li>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]28 <li><a href="#Developer">Developer corner</a></li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]29</ul>
30
31<h2><a name="Licence">Licence</a>(s)</h2>
32<ol>
33 <li><em>Licensing Terms for libxml</em>
34 <p>libxml is released under 2 (compatible) licences:</p>
35 <ul>
36 <li>the <a href="http://www.gnu.org/copyleft/lgpl.html">LGPL</a>: GNU
37 Library General Public License</li>
38 <li>the <a
39 href="http://www.w3.org/Consortium/Legal/copyright-software-19980720.html">W3C
40 IPR</a>: very similar to the XWindow licence</li>
41 </ul>
42 </li>
43 <li><em>Can I embed libxml in a proprietary application ?</em>
44 <p>Yes. The W3C IPR allows you to also keep proprietary the changes you
45 made to libxml, but it would be graceful to provide back bugfixes and
46 improvements as patches for possible incorporation in the main
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]47 development tree</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]48 </li>
49</ol>
50
51<h2><a name="Installati">Installation</a></h2>
52<ol>
53 <li><em>Where can I get libxml</em> ?
54 <p>The original distribution comes from <a
55 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> or <a
56 href="ftp://ftp.gnome.org/pub/GNOME/stable/sources/libxml/">gnome.org</a></p>
57 <p>Most linux and Bsd distribution includes libxml, this is probably the
58 safer way for end-users</p>
59 <p>David Doolin provides precompiled Windows versions at <a
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]60 href="http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/ ">http://www.ce.berkeley.edu/~doolin/code/libxmlwin32/</a></p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]61 </li>
62 <li><em>I see libxml and libxml2 releases, which one should I install ?</em>
63 <ul>
64 <li>If you are not concerned by any existing backward compatibility with
65 existing application, install libxml2 only</li>
66 <li>If you are not doing development, you can safely install both.
67 usually the packages <a
68 href="http://rpmfind.net/linux/RPM/libxml.html">libxml</a> and <a
69 href="http://rpmfind.net/linux/RPM/libxml2.html">libxml2</a> are
70 compatible (this is not the case for development packages)</li>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]71 <li>If you are a developer and your system provides separate packaging
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]72 for shared libraries and the development components, it is possible to
73 install libxml and libxml2, and depending on your development needs
74 have either <a
75 href="http://rpmfind.net/linux/RPM/libxml-devel.html">libxml-devel</a>
76 or <a
77 href="http://rpmfind.net/linux/RPM/libxml2-devel.html">libxml2-devel</a>
78 too</li>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]79 <li>If you are developing a new application, please develop against
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]80 libxml2(-devel)</li>
81 </ul>
82 </li>
83 <li><em>I can't install the libxml package it conflicts with libxml0</em>
84 <p>You probably have an old libxml0 package used to provide the shared
85 library for libxml.so.0, you can probably safely remove it. Anyway the
86 libxml packages provided on <a
87 href="ftp://rpmfind.net/pub/libxml/">rpmfind.net</a> provides
88 libxml.so.0</p>
89 </li>
90</ol>
91
92<h2><a name="Compilatio">Compilation</a></h2>
93<ol>
94 <li><em>What is the process to compile libxml ?</em>
95 <p>As most UNIX libraries libxml follows the "standard":</p>
96 <p><code>gunzip -c xxx.tar.gz | tar xvf -</code></p>
97 <p><code>cd libxml-xxxx</code></p>
98 <p><code>./configure --help</code></p>
99 <p>to see the options, then the compilation/installation proper</p>
100 <p><code>./configure [possible options]</code></p>
101 <p><code>make</code></p>
102 <p><code>make install</code></p>
103 <p>At that point you may have to rerun ldconfig or similar utility to
104 update your list of installed shared libs.</p>
105 </li>
106 <li><em>What other libraries are needed to compile/install libxml ?</em>
107 <p>Libxml does not requires any other library, the normal C ANSI API
108 should be sufficient (please report any violation to this rule you may
109 find).</p>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]110 <p>However if found at configuration time libxml will detect and use the
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]111 following libs:</p>
112 <ul>
113 <li><a href="http://www.info-zip.org/pub/infozip/zlib/">libz</a>: a
114 highly portable and available widely compression library</li>
115 <li>iconv: a powerful character encoding conversion library. It's
116 included by default on recent glibc libraries, so it doesn't need to
117 be installed specifically on linux. It seems it's now <a
118 href="http://www.opennc.org/onlinepubs/7908799/xsh/iconv.html">part of
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]119 the official UNIX</a> specification. Here is one <a
120 href="http://clisp.cons.org/~haible/packages-libiconv.html">implementation
121 of the library</a> which source can be found <a
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]122 href="ftp://ftp.ilog.fr/pub/Users/haible/gnu/">here</a>.</li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]123 </ul>
124 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]125 <li><em>libxml does not compile with HP-UX's optional ANSI-C compiler</em>
126 <p>this is due to macro limitations. Try to add " -Wp,-H16800 -Ae" to the
127 CFLAGS</p>
128 <p>you can also install and use gcc instead or use a precompiled version
129 of libxml, both available from the <a
130 href="http://hpux.cae.wisc.edu/hppd/auto/summary_all.html">HP-UX Porting
131 and Archive Centre</a></p>
132 </li>
133 <li><em>make check fails on some platforms</em>
134 <p>Sometime the regression tests results don't completely match the value
135 produced by the parser, and the makefile uses diff to print the delta. On
136 some platforms the diff return breaks the compilation process, if the diff
137 is small this is probably not a serious problem</p>
138 </li>
139</ol>
140
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]141<h2><a name="Developer">Developer</a> corner</h2>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]142<ol>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]143 <li>Extra nodes in the document:
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]144 <p><em>For a XML file as below:</em></p>
145 <pre>&lt;?xml version="1.0"?&gt;
Daniel Veillarda6663592001-02-10 09:41:12 +0000[diff] [blame]146&lt;PLAN xmlns="http://www.argus.ca/autotest/1.0/"&gt;
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]147&lt;NODE CommFlag="0"/&gt;
148&lt;NODE CommFlag="1"/&gt;
149&lt;/PLAN&gt;</pre>
150 <p><em>after parsing it with the function pxmlDoc=xmlParseFile(...);</em></p>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]151 <p><em>I want to the get the content of the first node (node with the
152 CommFlag="0")</em></p>
153 <p><em>so I did it as following;</em></p>
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]154 <pre>xmlNodePtr pode;
155pnode=pxmlDoc-&gt;children-&gt;children;</pre>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]156 <p><em>but it does not work. If I change it to</em></p>
Daniel Veillard62bccd52001-02-10 09:40:10 +0000[diff] [blame]157 <pre>pnode=pxmlDoc-&gt;children-&gt;children-&gt;next;</pre>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]158 <p><em>then it works. Can someone explain it to me.</em></p>
159 <p></p>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]160 <p>In XML all characters in the content of the document are significant
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]161 <strong>including blanks and formatting line breaks</strong>.</p>
162 <p>The extra nodes you are wondering about are just that, text nodes with
163 the formatting spaces wich are part of the document but that people tend
164 to forget. There is a function <a
165 href="http://xmlsoft.org/html/libxml-parser.html">xmlKeepBlanksDefault
166 ()</a> to remove those at parse time, but that's an heuristic, and its
167 use should be limited to case where you are sure there is no mixed-content
168 in the document.</p>
169 </li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]170 <li><em>I get compilation errors of existing code like when accessing
171 <strong>root</strong> or <strong>childs fields</strong> of nodes</em>
Daniel Veillard3f3b4f32001-03-13 15:12:39 +0000[diff] [blame^]172 <p>You are compiling code developed for libxml version 1 and using a
173 libxml2 development environment. Either switch back to libxml v1 devel or
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]174 even better fix the code to compile with libxml2 (or both) by <a
175 href="upgrade.html">following the instructions</a>.</p>
176 </li>
177 <li><em>I get compilation errors about non existing
178 <strong>xmlRootNode</strong> or <strong>xmlChildrenNode</strong>
179 fields</em>
180 <p>The source code you are using has been <a
181 href="upgrade.html">upgraded</a> to be able to compile with both libxml
182 and libxml2, but you need to install a more recent version: libxml(-devel)
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]183 &gt;= 1.8.8 or libxml2(-devel) &gt;= 2.1.0</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]184 </li>
185 <li><em>XPath implementation looks seriously broken</em>
Daniel Veillard7f41b3e2001-02-10 09:35:37 +0000[diff] [blame]186 <p>XPath implementation prior to 2.3.0 was really incomplete, upgrade to a
187 recent version, the implementation and debug of libxslt generated fixes
188 for most obvious problems. </p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]189 </li>
190 <li><em>The example provided in the web page does not compile</em>
191 <p>It's hard to maintain the documentation in sync with the code
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]192 &lt;grin/&gt; ...</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]193 <p>Check the previous points 1/ and 2/ raised before, and send
194 patches.</p>
195 </li>
196 <li><em>Where can I get more examples and informations than in the web
197 page</em>
198 <p>Ideally a libxml book would be nice. I have no such plan ... But you
199 can:</p>
200 <ul>
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]201 <li>check more deeply the <a href="html/libxml-lib.html">existing
202 generated doc</a></li>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]203 <li>looks for examples of use for libxml function using the Gnome code
204 for example the following will query the full Gnome CVs base for the
205 use of the <strong>xmlAddChild()</strong> function:
206 <p><a
207 href="http://cvs.gnome.org/lxr/search?string=xmlAddChild">http://cvs.gnome.org/lxr/search?string=xmlAddChild</a></p>
208 <p>This may be slow, a large hardware donation to the gnome project
209 could cure this :-)</p>
210 </li>
211 <li><a
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]212 href="http://cvs.gnome.org/bonsai/rview.cgi?cvsroot=/cvs/gnome&amp;dir=gnome-xml">Browse
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]213 the libxml source</a>, I try to write code as clean and documented as
214 possible, so looking at it may be helpful</li>
215 </ul>
216 </li>
217 <li>What about C++ ?
218 <p>libxml is written in pure C in order to allow easy reuse on a number of
219 platforms, including embedded systems. I don't intend to convert to
220 C++.</p>
221 <p>There is however a C++ wrapper provided by Ari Johnson
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]222 &lt;ari@btigate.com&gt; which may fullfill your needs:</p>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]223 <p>Website: <a
224 href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a></p>
225 <p>Download: <a
226 href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a></p>
227 </li>
228 <li>How to validate a document a posteriori ?
229 <p>It is possible to validate documents which had not been validated at
230 initial parsing time or documents who have been built from scratch using
231 the API. Use the <a
Daniel Veillard9cb5ff42001-01-29 08:22:21 +0000[diff] [blame]232 href="http://xmlsoft.org/html/libxml-valid.html#XMLVALIDATEDTD">xmlValidateDtd()</a>
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]233 function. It is also possible to simply add a Dtd to an existing
234 document:</p>
235 <pre>xmlDocPtr doc; /* your existing document */
236 xmlDtdPtr dtd = xmlParseDTD(NULL, filename_of_dtd); /* parse the DTD */
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]237 dtd-&gt;name = xmlStrDup((xmlChar*)"root_name"); /* use the given root */
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]238
Daniel Veillarde9202a02000-10-16 16:58:19 +0000[diff] [blame]239 doc-&gt;intSubset = dtd;
240 if (doc-&gt;children == NULL) xmlAddChild((xmlNodePtr)doc, (xmlNodePtr)dtd);
241 else xmlAddPrevSibling(doc-&gt;children, (xmlNodePtr)dtd);
Daniel Veillardaf743792000-07-01 11:49:28 +0000[diff] [blame]242 </pre>
243 </li>
244 <li>etc ...</li>
245</ol>
246
247<p><a href="mailto:Daniel.Veillard@w3.org">Daniel Veillard</a></p>
248
249<p>$Id$</p>
250</body>
251</html>