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Re: Importing schemata into WSDL

From: Sanjiva Weerawarana <sanjiva@watson.ibm.com>
Date: Sat, 12 Oct 2002 05:24:12 +0600
Message-ID: <019201c2717d$50ad4aa0$8100a8c0@lankabook2>
To: "Jacek Kopecky" <jacek@systinet.com>, "WS Description WG" <www-ws-desc@w3.org>

This is getting into more XSD than I understand. Intuitively I
don't see any problem with importing XSDs using its import
mechanism rather than schema's. 

Would Gudge or anyone else who's more XSD aware than I care to 


----- Original Message ----- 
From: "Jacek Kopecky" <jacek@systinet.com>
To: "WS Description WG" <www-ws-desc@w3.org>
Sent: Friday, October 11, 2002 11:15 PM
Subject: Importing schemata into WSDL

> Hi all, 8-)
> in WSDL 1.1 the import statement allowed importing schema documents. In
> WSDL 1.2 we are apprarently moving in the direction of disallowing this,
> but we acknowledge it must be possible to import an external schema into
> a WSDL definitions document somehow.
> What I've heard from Gudge is that it is possible to import a schema at
> http://example.org/schema.xs (with the same target namespace) using
> <wsdl:types>
>   <xs:schema>
>     <xs:import namespace="http://example.org/schema.xs"
>                location="http://example.org/schema.xs"/>
>   </xs:schema>
> </wsdl:types>
> I have a problem with this because IMHO this violates XML Schema import
> semantics. Let me explain:
> Let's assume I have three schemas, a.xs, b.xs and c.xs, with different
> target namespaces; where a.xs only imports b.xs and b.xs imports c.xs.
> On the component level; a.xs then contains all the type and element
> definitions from a.xs and all the type and element definitions from b.xs
> are accessible in a.xs. 
> Note that no definitions from c.xs are visible in a.xs - this is logical
> because the fact that b.xs imports c.xs is just an implementation detail
> of b.xs and should not be propagated outside of b.xs. In other words,
> a.xs must not be affected by a change to b.xs that only removes the
> import and redefines those definitions (still in b.xs) that used
> definitions from c.xs.
> What I think this means is that an xs:schema element (together with any
> contents) is a syntactic representation of the set of type and element
> definitions contained within.
> I think it's apparent from the paragraph above that WSDL should not know
> about imports in wsdl:types/xs:schema. I.e. a schema cannot be imported
> into a WSDL definitions document by importing it in a contained schema.
> I think that we'll have to reallow our import statement to import
> schemas (which should be doable in a safe way, I believe) or we should
> introduce a typesImport statement that would serve to import external
> schemata, as the types statement serves to provide (import) internal
> schemata.
> Hope it makes sense,
>                    Jacek Kopecky
>                    Senior Architect, Systinet Corporation
>                    http://www.systinet.com/
Received on Friday, 11 October 2002 19:26:01 UTC

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