Another Summary of Validation in the face of Namespaces

Mark Tucker mct at
Fri Sep 11 21:35:37 BST 1998

Before the question of Validation of documents that use
namespaces gets lost, I think we are near closure.

We have a 5 step procedure for making unique prefixes, then performing
normal validation.
The open issues are:
	[Step 4] How do you actually define the URI's for namespace
	prefixes used in a DTD?

	[Setp 4a] How do we actually __find__ the DTD's we need?

		   The document instance specifies URI's, but
		   the URI's are not "de-referencable".
	[Question] Several people mentioned 
	       "If Namespaces still used the old PI method
	       of defining prefixes, there would be no problem."
	       Can anyone explain the old PI method?

The algorithm	
	 There is a (5) step algorithm for validating
	   a document against a set of DTDS
		1. Determine the Expanded the names the way the
		Namespace Proposal says. (Section 6.3)
		2. Define a unique prefix for each namespace definition URI .

		3. Rewrite the element or attribute, prepending the
		(possibly generated) unique prefix for the namespace
		of the element/attributes Expanded Name.
		   This give you  P1:BOOK, P1:NAME, P3:ADDRESS
		   if BOOK and NAME come from the same namespace URI.
		4. Do the same to the DTD's that you read in.
		    4.a Find the relevant DTD's
		5. Do normal DTD validation of the rewritten instance 
		   document against the rewritten DTD.

The following document instance is legal:

	A Document Instance

    <J1:NAME V="Xml Made Easy"/>
    <J2:ADDRESS V="Holland"/>

   The J1 and J2 are fine, because the prefix doesn't matter.

This is where there is still a problem.
How do we define the URI's for the prefixes that the DTD uses?

	A DTD for defining Address 
<!DOCTYPE location_dtd [

	xmlns:K="uri:locatie"		<<< -- How can we stick this in there?

	v #pcdata>

	A DTD for defining Address
<!DOCTYPE library_dtd [

	xmlns:K="uri:bibliotheque"	 <<< -- How can we stick this in there?

	v #pcdata>

Mark Tucker			tucker_m at
Regenstrief Institute		phone: (317) 630-2606
1001 W. 10'th St; Indianapolis, IN; 46202-2859;	fax: (317) 630-6962

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