doc/valid.html - fp2-dev/platform/external/libxml2 - Gitiles

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 <h1>The XML C library for Gnome</h1>
 <h2>Validation, or are you afraid of DTDs ?</h2>
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 <p>Well what is validation and what is a DTD ?</p>
 <p>Validation is the process of checking a document against a set of
 construction rules; a <strong>DTD</strong> (Document Type Definition) is such
 a set of rules.</p>
 <p>The validation process and building DTDs are the two most difficult parts
 of the XML life cycle. Briefly a DTD defines all the possibles element to be
 found within your document, what is the formal shape of your document tree
 (by defining the allowed content of an element, either text, a regular
 expression for the allowed list of children, or mixed content i.e. both text
 and children). The DTD also defines the allowed attributes for all elements
 and the types of the attributes. For more detailed information, I suggest
 that you read the related parts of the XML specification, the examples found
 under gnome-xml/test/valid/dtd and any of the large number of books available
 on XML. The dia example in gnome-xml/test/valid should be both simple and
 complete enough to allow you to build your own.</p>
 <p>A word of warning, building a good DTD which will fit the needs of your
 application in the long-term is far from trivial; however, the extra level of
 quality it can ensure is well worth the price for some sets of applications
 or if you already have already a DTD defined for your application field.</p>
 <p>The validation is not completely finished but in a (very IMHO) usable
 state. Until a real validation interface is defined the way to do it is to
 define and set the <strong>xmlDoValidityCheckingDefaultValue</strong>
 external variable to 1, this will of course be changed at some point:</p>
 <p>extern int xmlDoValidityCheckingDefaultValue;</p>
 <p>...</p>
 <p>xmlDoValidityCheckingDefaultValue = 1;</p>
 <p>
 <p>To handle external entities, use the function
 <strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
 link in you HTTP/FTP/Entities database library to the standard libxml
 core.</p>
 <p>@@interfaces@@</p>
 <p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p>
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	<h1>The XML C library for Gnome</h1>
	<h2>Validation, or are you afraid of DTDs ?</h2>
	</td></tr></table></td></tr></table></td>
	</tr></table>
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	<li><a href="valid.html">Validation, or are you afraid of DTDs ?</a></li>
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	<li><a href="example.html">A real example</a></li>
	<li><a href="contribs.html">Contributions</a></li>
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	<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
	<tr><td bgcolor="#fffacd"><ul style="margin-left: -2pt">
	<li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li>
	<li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li>
	<li><a href="http://www.cs.unibo.it/~casarini/gdome2/">DOM gdome2</a></li>
	<li><a href="ftp://xmlsoft.org/">FTP</a></li>
	<li><a href="http://www.fh-frankfurt.de/~igor/projects/libxml/">Windows binaries</a></li>
	<li><a href="http://pages.eidosnet.co.uk/~garypen/libxml/">Solaris binaries</a></li>
	</ul></td></tr>
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	<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">
	<p>Well what is validation and what is a DTD ?</p>
	<p>Validation is the process of checking a document against a set of
	construction rules; a <strong>DTD</strong> (Document Type Definition) is such
	a set of rules.</p>
	<p>The validation process and building DTDs are the two most difficult parts
	of the XML life cycle. Briefly a DTD defines all the possibles element to be
	found within your document, what is the formal shape of your document tree
	(by defining the allowed content of an element, either text, a regular
	expression for the allowed list of children, or mixed content i.e. both text
	and children). The DTD also defines the allowed attributes for all elements
	and the types of the attributes. For more detailed information, I suggest
	that you read the related parts of the XML specification, the examples found
	under gnome-xml/test/valid/dtd and any of the large number of books available
	on XML. The dia example in gnome-xml/test/valid should be both simple and
	complete enough to allow you to build your own.</p>
	<p>A word of warning, building a good DTD which will fit the needs of your
	application in the long-term is far from trivial; however, the extra level of
	quality it can ensure is well worth the price for some sets of applications
	or if you already have already a DTD defined for your application field.</p>
	<p>The validation is not completely finished but in a (very IMHO) usable
	state. Until a real validation interface is defined the way to do it is to
	define and set the <strong>xmlDoValidityCheckingDefaultValue</strong>
	external variable to 1, this will of course be changed at some point:</p>
	<p>extern int xmlDoValidityCheckingDefaultValue;</p>
	<p>...</p>
	<p>xmlDoValidityCheckingDefaultValue = 1;</p>
	<p>
	<p>To handle external entities, use the function
	<strong>xmlSetExternalEntityLoader</strong>(xmlExternalEntityLoader f); to
	link in you HTTP/FTP/Entities database library to the standard libxml
	core.</p>
	<p>@@interfaces@@</p>
	<p><a href="mailto:daniel@veillard.com">Daniel Veillard</a></p>
	</td></tr></table></td></tr></table></td></tr></table></td>
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