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target namespace and namespaces

From: Dan Vint <dvint@dvint.com>
Date: Thu, 02 Dec 2004 15:03:00 -0800
Message-Id: <>
To: xmlschema-dev@w3.org

Can someone help with a better understanding of the relationship of a 
target namespace, the namespace and a schema composed of multiple files?

Let me build an example:

1) I create a schema (all in one file) and assign a namespace and 
targetNamespace. A data stream that references this namespace gets the 
entire schema and alls it definitions. To me 1 namespace = 1 schema and in 
this case there is no option to break it up.

2) Now take the same schema and break it up into separate files. I have one 
file with common stuff and two other files that include this common file, 
but each adds different containing elements. Both of these files have the 
same namespace associated with them. Now I have 1 namespace = 2 different 
schemas. A data stream that validates against schema 1 with namespace=foo 
will not validate against schema 2 with namespace=foo. A substantial amount 
may be legal because of the shared common information but the upper wrapper 
elements would immediately fail validation.

Is there anything that considers method 2 a legal design?

If it isn't illegal is it at least a really poor and troublesome design?

In the Namespace spec I can't see any guidance on this question and with 
the schema spec saying schema location information is optional and at best 
a hint I don't see any help there either. With the schema location info 
being a "hint" there seems to be no way to make clear that I would want 
namespace foo with schema 1 rather than schema 2. So I lean towards this 
not being necessarily illegal, but a REALLLLLY poor design.

I've also got a request for a variation on method 2. In this case I have 
another group that wants one or two elements and code lists out of my 
entire schema for reuse. They want me to place these few items in a 
separate file that is included into my massive schema. They want to address 
these reusable items by the same namespace that applies to the entire 
specification, but say that wen they reference this namespace that they 
only mean the file with the reusable portions.

In this option I think there is actually a mechanical problem. The main 
schema file is going to have the target namespace defined. Include requires 
the included file to not have a namespace, but is there any problem with 
importing a file with the same namespace? So in this case the reusable file 
has the same namespace assigned as the importing schema - is a parser 
supposed to just "blend" these two sets of definitions together or is this 
an error.

thanks for any light and opinions you can shed on this issue.

Danny Vint

Specializing in Panoramic Images of California and the West

voice: 510-522-4703
fax: 801-749-3229

Received on Thursday, 2 December 2004 23:01:17 UTC

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