SAX2: DeclHandler

Khun Yee Fung kyeefung at extend.com
Wed Dec 22 15:31:26 GMT 1999


I have a question. Right now, the Xerces SAX implementation calls the
comment() method when a comment is encountered in a DTD. Is this the
intended behaviour?

As to whether element and attribute declarations are useful for downstream
processing. I did find a use. In XPath, there is a function called 'id()'
which returns a node with a certain ID. Without getting access to the DTD,
it is actually quite difficult to find out which attribute is the ID of an
element.

Regards,
Khun Yee Fung

		-----Original Message-----
		From:	David Megginson [mailto:david at megginson.com]
<mailto:[mailto:david at megginson.com]> 
		Sent:	Wednesday, December 22, 1999 9:35 AM
		To:	XMLDev list
		Subject:	SAX2: DeclHandler

		Here's the DeclHandler that we designed for SAX2alpha, with
		IOException replacing SAXException in the throws clauses:

		  public interface DeclHandler
		  {
		    public void elementDecl (String name, String model)
throws IOException;
		    public void attributeDecl (String eName, String name,
String type,
					       String valueDefault, String
value)
		      throws IOException;
		    public void internalEntityDecl (String name, String
value)
		      throws IOException;

		    public void externalEntityDecl (String name, String
publicId,
						    String systemId)
		      throws IOException;
		  }

		Notes:

		1. Unparsed entity and notation declarations are reported by
the (now
		   confusingly-named) DTDHandler.  The distinction is that
the XML 1.0 
		   REC requires parsers to report unparsed-entity and
notation
		   declarations, but not other DTD-based declarations.

		2. The model argument in elementDecl is a normalized string
		   representation of a content model.  It's not ideal, but
everyone
		   agreed last time that it was workable.

		This interface seems hopelessly anachronistic, and I'm not
willing to
		invest too much time in it -- after all, while DTDs are
useful in
		themselves, the declarations should hardly form part of
downstream
		processing -- but enough people want it that it's useful to
include it
		as an optional feature.


		All the best,


		David

		-- 
		David Megginson                 david at megginson.com
<mailto:david at megginson.com> 
		           http://www.megginson.com/
<http://www.megginson.com/> 

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