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Daniel Veillardc9484202001-10-24 12:35:52 +00001<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "http://www.w3.org/TR/REC-html40/loose.dtd">
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12<title>The SAX interface</title>
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20<h1>The XML C library for Gnome</h1>
21<h2>The SAX interface</h2>
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57<p>Sometimes the DOM tree output is just too large to fit reasonably into
58memory. In that case (and if you don't expect to save back the XML document
59loaded using libxml), it's better to use the SAX interface of libxml. SAX is
60a <strong>callback-based interface</strong> to the parser. Before parsing,
61the application layer registers a customized set of callbacks which are
62called by the library as it progresses through the XML input.</p>
63<p>To get more detailed step-by-step guidance on using the SAX interface of
64libxml, see the <a href="http://www.daa.com.au/~james/gnome/xml-sax/xml-sax.html">nice
65documentation</a>.written by <a href="mailto:james@daa.com.au">James
66Henstridge</a>.</p>
67<p>You can debug the SAX behaviour by using the <strong>testSAX</strong>
68program located in the gnome-xml module (it's usually not shipped in the
69binary packages of libxml, but you can find it in the tar source
70distribution). Here is the sequence of callbacks that would be reported by
71testSAX when parsing the example XML document shown earlier:</p>
72<pre>SAX.setDocumentLocator()
73SAX.startDocument()
74SAX.getEntity(amp)
75SAX.startElement(EXAMPLE, prop1='gnome is great', prop2='&amp;amp; linux too')
76SAX.characters( , 3)
77SAX.startElement(head)
78SAX.characters( , 4)
79SAX.startElement(title)
80SAX.characters(Welcome to Gnome, 16)
81SAX.endElement(title)
82SAX.characters( , 3)
83SAX.endElement(head)
84SAX.characters( , 3)
85SAX.startElement(chapter)
86SAX.characters( , 4)
87SAX.startElement(title)
88SAX.characters(The Linux adventure, 19)
89SAX.endElement(title)
90SAX.characters( , 4)
91SAX.startElement(p)
92SAX.characters(bla bla bla ..., 15)
93SAX.endElement(p)
94SAX.characters( , 4)
95SAX.startElement(image, href='linus.gif')
96SAX.endElement(image)
97SAX.characters( , 4)
98SAX.startElement(p)
99SAX.characters(..., 3)
100SAX.endElement(p)
101SAX.characters( , 3)
102SAX.endElement(chapter)
103SAX.characters( , 1)
104SAX.endElement(EXAMPLE)
105SAX.endDocument()</pre>
106<p>Most of the other interfaces of libxml are based on the DOM tree-building
107facility, so nearly everything up to the end of this document presupposes the
108use of the standard DOM tree build. Note that the DOM tree itself is built by
109a set of registered default callbacks, without internal specific
110interface.</p>
111<p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p>
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