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22<h1>The XML C library for Gnome</h1>
23<h2>Python and bindings</h2>
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74<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
75<tr><td bgcolor="#fffacd"><ul>
76<li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li>
77<li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li>
78<li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]79<li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]80<li><a href="ftp://xmlsoft.org/">FTP</a></li>
81<li><a href="http://www.fh-frankfurt.de/~igor/projects/libxml/">Windows binaries</a></li>
82<li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillarde6d8e202002-05-02 06:11:10 +0000[diff] [blame]83<li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]84<li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml&amp;product=libxml2">Bug Tracker</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]85</ul></td></tr>
86</table>
87</td></tr></table></td>
88<td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd">
89<p>There is a number of language bindings and wrappers available for libxml2,
90the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
91(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
92order to get updates to this list or to discuss the specific topic of libxml2
93or libxslt wrappers or bindings:</p>
94<ul>
95<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]96<a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
97 for libxml:<br>
Daniel Veillard9b6fd302002-05-13 12:06:47 +0000[diff] [blame^]98 Website: <a href="http://lusis.org/~ari/xml%2B%2B/">http://lusis.org/~ari/xml++/</a><br>
99 Download: <a href="http://lusis.org/~ari/xml%2B%2B/libxml%2B%2B.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]100</li>
101<li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
102 based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
Daniel Veillard9b6fd302002-05-13 12:06:47 +0000[diff] [blame^]103<li>and a third C++ wrapper by Peter Jones &lt;pjones@pmade.org&gt;
104 <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a>
105</p>
106</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]107<li>
108<a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]109 Sergeant</a> developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
110 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
111 application server</a>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]112</li>
113<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]114<a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
115 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]116</li>
117<li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
118 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
Daniel Veillardb2fb8ed2002-04-01 09:33:12 +0000[diff] [blame]119<li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2
Daniel Veillarda8a89fe2002-04-12 21:03:34 +0000[diff] [blame]120 implementation for Kylix2/D5/D6 from Borland</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]121<li>Wai-Sun &quot;Squidster&quot; Chia provides <a href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
122 libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
123 maintained by Tobias Peters.</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]124<li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
Daniel Veillardb9e469a2002-02-21 12:08:42 +0000[diff] [blame]125 Tcl</a>
126</li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]127<li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]128</ul>
129<p>The distribution includes a set of Python bindings, which are garanteed to
130be maintained as part of the library in the future, though the Python
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]131interface have not yet reached the maturity of the C API.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]132<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]133<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]134<li>If you use an RPM based distribution, simply install the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python
135 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
136 RPM</a>).</li>
137<li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
138 module distribution</a> corresponding to your installed version of
139 libxml2 and libxslt. Note that to install it you will need both libxml2
140 and libxslt installed and run &quot;python setup.py build install&quot; in the
141 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]142</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]143<p>The distribution includes a set of examples and regression tests for the
144python bindings in the <code>python/tests</code> directory. Here are some
145excepts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]146<h3>tst.py:</h3>
147<p>This is a basic test of the file interface and DOM navigation:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]148<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]149
150doc = libxml2.parseFile(&quot;tst.xml&quot;)
151if doc.name != &quot;tst.xml&quot;:
152 print &quot;doc.name failed&quot;
153 sys.exit(1)
154root = doc.children
155if root.name != &quot;doc&quot;:
156 print &quot;root.name failed&quot;
157 sys.exit(1)
158child = root.children
159if child.name != &quot;foo&quot;:
160 print &quot;child.name failed&quot;
161 sys.exit(1)
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]162doc.freeDoc()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]163<p>The Python module is called libxml2, parseFile is the equivalent of
164xmlParseFile (most of the bindings are automatically generated, and the xml
165prefix is removed and the casing convention are kept). All node seen at the
166binding level share the same subset of accesors:</p>
167<ul>
168<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]169<code>name</code> : returns the node name</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]170<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]171<code>type</code> : returns a string indicating the node
172 typ<code>e</code>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]173</li>
174<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]175<code>content</code> : returns the content of the node, it is based on
176 xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]177<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]178<code>parent</code> , <code>children</code>, <code>last</code>,
179 <code>next</code>, <code>prev</code>, <code>doc</code>,
180 <code>properties</code>: pointing to the associated element in the tree,
181 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]182</ul>
183<p>Also note the need to explicitely deallocate documents with freeDoc() .
184Reference counting for libxml2 trees would need quite a lot of work to
185function properly, and rather than risk memory leaks if not implemented
186correctly it sounds safer to have an explicit function to free a tree. The
187wrapper python objects like doc, root or child are them automatically garbage
188collected.</p>
189<h3>validate.py:</h3>
190<p>This test check the validation interfaces and redirection of error
191messages:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]192<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]193
194#desactivate error messages from the validation
195def noerr(ctx, str):
196 pass
197
198libxml2.registerErrorHandler(noerr, None)
199
200ctxt = libxml2.createFileParserCtxt(&quot;invalid.xml&quot;)
201ctxt.validate(1)
202ctxt.parseDocument()
203doc = ctxt.doc()
204valid = ctxt.isValid()
205doc.freeDoc()
206if valid != 0:
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]207 print &quot;validity chec failed&quot;</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]208<p>The first thing to notice is the call to registerErrorHandler(), it
209defines a new error handler global to the library. It is used to avoid seeing
210the error messages when trying to validate the invalid document.</p>
211<p>The main interest of that test is the creation of a parser context with
212createFileParserCtxt() and how the behaviour can be changed before calling
213parseDocument() . Similary the informations resulting from the parsing phase
214are also available using context methods.</p>
215<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
216C function interfaces in terms of objects method as much as possible. The
217best to get a complete view of what methods are supported is to look at the
218libxml2.py module containing all the wrappers.</p>
219<h3>push.py:</h3>
220<p>This test show how to activate the push parser interface:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]221<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]222
223ctxt = libxml2.createPushParser(None, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
224ctxt.parseChunk(&quot;/&gt;&quot;, 2, 1)
225doc = ctxt.doc()
226
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]227doc.freeDoc()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]228<p>The context is created with a speciall call based on the
229xmlCreatePushParser() from the C library. The first argument is an optional
230SAX callback object, then the initial set of data, the lenght and the name of
231the resource in case URI-References need to be computed by the parser.</p>
232<p>Then the data are pushed using the parseChunk() method, the last call
233setting the thrird argument terminate to 1.</p>
234<h3>pushSAX.py:</h3>
235<p>this test show the use of the event based parsing interfaces. In this case
236the parser does not build a document, but provides callback information as
237the parser makes progresses analyzing the data being provided:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]238<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]239log = &quot;&quot;
240
241class callback:
242 def startDocument(self):
243 global log
244 log = log + &quot;startDocument:&quot;
245
246 def endDocument(self):
247 global log
248 log = log + &quot;endDocument:&quot;
249
250 def startElement(self, tag, attrs):
251 global log
252 log = log + &quot;startElement %s %s:&quot; % (tag, attrs)
253
254 def endElement(self, tag):
255 global log
256 log = log + &quot;endElement %s:&quot; % (tag)
257
258 def characters(self, data):
259 global log
260 log = log + &quot;characters: %s:&quot; % (data)
261
262 def warning(self, msg):
263 global log
264 log = log + &quot;warning: %s:&quot; % (msg)
265
266 def error(self, msg):
267 global log
268 log = log + &quot;error: %s:&quot; % (msg)
269
270 def fatalError(self, msg):
271 global log
272 log = log + &quot;fatalError: %s:&quot; % (msg)
273
274handler = callback()
275
276ctxt = libxml2.createPushParser(handler, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
277chunk = &quot; url='tst'&gt;b&quot;
278ctxt.parseChunk(chunk, len(chunk), 0)
279chunk = &quot;ar&lt;/foo&gt;&quot;
280ctxt.parseChunk(chunk, len(chunk), 1)
281
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame]282reference = &quot;startDocument:startElement foo {'url': 'tst'}:&quot; + \
283 &quot;characters: bar:endElement foo:endDocument:&quot;
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]284if log != reference:
285 print &quot;Error got: %s&quot; % log
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]286 print &quot;Exprected: %s&quot; % reference</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]287<p>The key object in that test is the handler, it provides a number of entry
288points which can be called by the parser as it makes progresses to indicate
289the information set obtained. The full set of callback is larger than what
290the callback class in that specific example implements (see the SAX
291definition for a complete list). The wrapper will only call those supplied by
292the object when activated. The startElement receives the names of the element
293and a dictionnary containing the attributes carried by this element.</p>
294<p>Also note that the reference string generated from the callback shows a
295single character call even though the string &quot;bar&quot; is passed to the parser
296from 2 different call to parseChunk()</p>
297<h3>xpath.py:</h3>
298<p>This is a basic test of XPath warppers support</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]299<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]300
301doc = libxml2.parseFile(&quot;tst.xml&quot;)
302ctxt = doc.xpathNewContext()
303res = ctxt.xpathEval(&quot;//*&quot;)
304if len(res) != 2:
305 print &quot;xpath query: wrong node set size&quot;
306 sys.exit(1)
307if res[0].name != &quot;doc&quot; or res[1].name != &quot;foo&quot;:
308 print &quot;xpath query: wrong node set value&quot;
309 sys.exit(1)
310doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]311ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]312<p>This test parses a file, then create an XPath context to evaluate XPath
313expression on it. The xpathEval() method execute an XPath query and returns
314the result mapped in a Python way. String and numbers are natively converted,
315and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
316the document, the XPath context need to be freed explicitely, also not that
317the result of the XPath query may point back to the document tree and hence
318the document must be freed after the result of the query is used.</p>
319<h3>xpathext.py:</h3>
320<p>This test shows how to extend the XPath engine with functions written in
321python:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]322<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]323
324def foo(ctx, x):
325 return x + 1
326
327doc = libxml2.parseFile(&quot;tst.xml&quot;)
328ctxt = doc.xpathNewContext()
329libxml2.registerXPathFunction(ctxt._o, &quot;foo&quot;, None, foo)
330res = ctxt.xpathEval(&quot;foo(1)&quot;)
331if res != 2:
332 print &quot;xpath extension failure&quot;
333doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]334ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]335<p>Note how the extension function is registered with the context (but that
336part is not yet finalized, ths may change slightly in the future).</p>
337<h3>tstxpath.py:</h3>
338<p>This test is similar to the previousone but shows how the extension
339function can access the XPath evaluation context:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]340<pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]341 global called
342
343 #
344 # test that access to the XPath evaluation contexts
345 #
346 pctxt = libxml2.xpathParserContext(_obj=ctx)
347 ctxt = pctxt.context()
348 called = ctxt.function()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]349 return x + 1</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]350<p>All the interfaces around the XPath parser(or rather evaluation) context
351are not finalized, but it should be sufficient to do contextual work at the
352evaluation point.</p>
353<h3>Memory debugging:</h3>
354<p>last but not least, all tests starts with the following prologue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]355<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]356libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]357<p>and ends with the following epilogue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]358<pre>#memory debug specific
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]359libxml2.cleanupParser()
360if libxml2.debugMemory(1) == 0:
361 print &quot;OK&quot;
362else:
363 print &quot;Memory leak %d bytes&quot; % (libxml2.debugMemory(1))
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]364 libxml2.dumpMemory()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]365<p>Those activate the memory debugging interface of libxml2 where all
366alloacted block in the library are tracked. The prologue then cleans up the
367library state and checks that all allocated memory has been freed. If not it
368calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
369<p><a href="bugs.html">Daniel Veillard</a></p>
370</td></tr></table></td></tr></table></td></tr></table></td>
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