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Re: <import ... /> Question

From: <Noah_Mendelsohn@lotus.com>
Date: Tue, 19 Dec 2000 15:57:34 -0500
To: Andreas Kemkes <andreas@perceptronics.com>
Cc: andreas@perceptronics.com, www-xml-schema-comments@w3.org
Message-ID: <OFD3C4F7D9.DA3F1DBC-ON852569BA.0073A8EC@lotus.com>
Yes, what you want to do is permitted, but probably not quite for the 
reason you suspect.  In XML schema, you do not <import> a schema document, 
you <import> a namespace.  Doing the import merely documents your 
intention to use the namespace, largely so that tools can easily track the 
interdependency.  Circular imports and redundant imports are harmless. The 
schemaLocation attribute on <import> is optional, and it is a hint. From 
[1] we find: 

"The normalized value of the schemaLocation, if present, gives a hint as to 
where a schema document with declarations and definitions for that 
namespace (or none) may be found."

What a processor does with redundant or conflicting hints is up to the 
processor, except that the schema language prohibits conflicting or 
duplicate definitions or declarations of the same named component.  So, 
processors can be written to ignore such hints or to reflect warnings or 
errors to the caller, but no such warnings or errors are covered by the 
conformance rules for the schema language itself.  Hints are 
hints...errors in a hint do not generally result in mandatory errors 
(though processing you do as a result of choosing to act on a hint can 
result in an error.)

[1] http://www.w3.org/TR/xmlschema-1/#composition-schemaImport

Noah Mendelsohn                                    Voice: 1-617-693-4036
Lotus Development Corp.                            Fax: 1-617-693-8676
One Rogers Street
Cambridge, MA 02142

Andreas Kemkes <andreas@perceptronics.com>
Sent by: www-xml-schema-comments-request@w3.org
12/19/00 02:47 PM

        To:     www-xml-schema-comments@w3.org
        cc:     andreas@perceptronics.com, (bcc: Noah Mendelsohn/CAM/Lotus)
        Subject:        <import ... /> Question


I have an XML schema question that someone on this list hopefully
can answer:

If an XML schema foo.xsd imports another XLM schema bla.xsd, which
in turn imports the first XML schema foo.xsd, is it permitted?

I couldn't find any conclusive statement in the documents - it may
be there, I just didn't see it.  Pointers would be appreciated.


Received on Tuesday, 19 December 2000 16:06:29 UTC

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