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Re: locally scoped element decls and namespaces

From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
Date: 04 Jan 2000 12:50:09 +0000
To: Roger Costello <costello@mitre.org>
Cc: XML List <xml-dev@ic.ac.uk>, xml-schema-comments <www-xml-schema-comments@w3c.org>
Message-ID: <f5bzoumngqm.fsf@cogsci.ed.ac.uk>
Roger Costello <costello@mitre.org> writes:

> Let me see if I understand this correctly.  If I wish to indicate in the
> instance document that everything between <Person> and </Person>
> conforms to the schema in urn:person-schema/person-schema.xsd, then this
> is the correct syntax:
> 
> <t:Person xmlns:t="urn:person-schema"
>           xmlns:xsi="http://www.w3.org/1999/XMLSchema/instance"
>           xsi:schemaLocation="urn:person-schema
>                               urn:person-schema/person-schema.xsd">

     <fname>Helen</fname>
     <lname>Jones</lname>

<!-- or -->

     <t:fname>Helen</t:fname>
     <t:lname>Jones</t:lname>

> </t:Person>

With all respect to Andrew Layman, the working group has not yet
settled this question (what is the correct form for element GIs with
locally scoped declarations), which is logged as an outstanding issue.
There are strong arguments for and against both answers.

> If the above is correct, then please tell me what it means when we don't
> declare the namespace:
> 
> <Person xmlns:xsi="http://www.w3.org/1999/XMLSchema/instance"
>           xsi:schemaLocation="urn:person-schema
>                               urn:person-schema/person-schema.xsd">
>     <fname>Helen</fname>
>     <lname>Jones</lname>
> </Person>

There's something missing from your example, and the answer depends on 
which way you fill it in:

1) The default namespace is declared with the URI "urn:person-schema":

<Person xmlns:xsi="http://www.w3.org/1999/XMLSchema/instance"
        xmlns="urn:person-schema"
          xsi:schemaLocation="urn:person-schema
                              urn:person-schema/person-schema.xsd">
    <fname>Helen</fname>
    <lname>Jones</lname>
</Person>

which ONLY is coherent under the second (elements with locally-scoped
declarations are declared in the same namespace as their parent is
declared in) interpretation.  To produce a schema-valid instance under
the first (element with locally-scoped declarations are in NO
namespace) interpretation, the following would be required:

<Person xmlns:xsi="http://www.w3.org/1999/XMLSchema/instance"
        xmlns="urn:person-schema"
          xsi:schemaLocation="urn:person-schema
                              urn:person-schema/person-schema.xsd">
    <fname xmlns=''>Helen</fname>
    <lname xmlns=''>Jones</lname>
</Person>

2) You meant the document to not use any namespace at all:

<Person xmlns:xsi="http://www.w3.org/1999/XMLSchema/instance"
          xsi:schemaLocation="##what.goes.here???###
                              urn:person-schema/person-schema.xsd">
    <fname>Helen</fname>
    <lname>Jones</lname>
</Person>

We don't yet have a concrete syntax for indicating an association
between "no namespace" and a schema in xsi:schemaLocation.  We know we
need to fill this gap.  The locally-scoped element declaration issue
doesn't arise in this case, or rather both interpretations give the
same answer.

> /Roger
> 
> Andrew Layman wrote:
> > 
> > The first is the right interpretation of local namespaces.

Again, with respect, the question of whether locally-scoped element
declarations imply local namespace [partitions] has not been resolved
by the WG.

> > 
> > -----Original Message-----
> > From: Gabe Beged-Dov [mailto:begeddov@jfinity.com]
> > Sent: Monday, January 03, 2000 10:11 AM
> > To: XML List
> > Cc: xml-schema-comments
> > Subject: locally scoped element decls and namespaces
> > 
> > I have a hopefully simple question concerning locally
> > scoped element decls and namespaces. Here is an example
> > schema:
> > 
> > <schema targetNamespace='urn:person-schema'>
> >         <type name='Person'>
> >                 <element name='fname' type='string' />
> >                 <element name='lname' type='string' />
> >         </type>
> >         <element name='Person' type='Person' />
> > </schema>
> > 
> > Given this schema, here is an instance:
> > 
> > <t:Person xmlns:t='urn:person-schema'
> > 
> > xmlns:xsi='http://www.w3.org/1999/XMLSchema/instance'>
> >         <fname>Helen</fname>
> >         <lname>Jones</lname>
> > </t:Person>
> > 
> > Is this right or should fname and lname be bound to the
> > same namespace as Person, i.e.:
> > 
> > <t:Person xmlns:t='urn:person-schema'
> > 
> > xmlns:xsi='http://www.w3.org/1999/XMLSchema/instance'>
> >         <t:fname>Helen</t:fname>
> >         <t:lname>Jones</t:lname>
> > </t:Person>
> > 
> > Cordially from Corvallis,
> > 
> > Gabe Beged-Dov
> > 
> > --
> > ---------------------------
> > http://www.jfinity.com/gabe
> > 
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> 

-- 
  Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
     2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
	    Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk
		     URL: http://www.ltg.ed.ac.uk/~ht/
Received on Tuesday, 4 January 2000 07:50:18 GMT

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