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Re: Followup: multiple services sharing a name

From: Amelia A Lewis <alewis@tibco.com>
Date: Thu, 15 Jan 2004 11:57:14 -0500
To: David Booth <dbooth@w3.org>
Cc: www-ws-desc@w3.org
Message-id: <20040115115714.6a09dec9.alewis@tibco.com>

On Thu, 15 Jan 2004 11:23:58 -0500
David Booth <dbooth@w3.org> wrote:
> You presented two scenarios: one using XML Schema import, one without.
>  Let 
> me address them separately.
> 
> 1. In the case WITHOUT using XML Schema import, as I understand it the
> scenario you're presenting is as follows.  You would have one XML
> Schema per country code, and a given XML document would be validated
> against the appropriate XML Schema, based on prior knowledge of the
> country code.  In this case, it seems to me that you would probably
> also have one more "generic" XML Schema that uses "any" for the postal
> code area.  So the processing sequence would likely go like this: (a)
> A normal XML parser validates the document against the generic XML
> Schema; (b) Application code grabs the country code from the document,
> looks up the appropriate country-specific XML Schema; (c) a normal XML
> parser then validates the document against the country-specific XML
> Schema.
> 
> This looks fine to me.  I see nothing here that violates any Web 
> architecture, namespace or XML Schema principles.  It looks like a 
> reasonable way to transcend the limits of XML Schema for a particular 
> application.

Holy hand grenade of Antioch, batman!  No wonder we disagree.  I suggest
you take this to the Schema working group, and ask them to include it in
a primer, and be neutral to it.

> 2. In the case of using XML Schema import, as I understand it the
> scenario you're presenting is as follows.  You would have only one XML
> Schema, but it would contain a (single) import statement.  Based on
> the value of the country code attribute, the effect of the import
> statement would vary: it would cause the appropriate XML Schema
> fragment to be imported for that particular country code.
>
> The problem with this scenario is that it would require a customized
> XML Schema processor that would have to contain application-specific
> knowledge to know that it should perform the "import" differently
> based on the value of the country code attribute.  It could not be
> done with a regular, off-the-shelf XML Schema processor.  In other
> words, the semantics that you'd be ascribing to the XML Schema
> document would be beyond what XML Schema specification says.

Which is exactly the same situation encountered in the multiple schemas
case.  In each case, you go to a catalog to get the schema or schema
import.  It's always the catalog's problem.

I very much doubt that the schema working group would be willing to
accept either of these.  Possibly they would, since it would mean that
they could mark the co-occurrence constraint issue as closed.  But it
would surprise me.

I certainly feel that being "neutral" toward the incredibly evil hack of
separating a WSDL into parts so that service names can be reused, in
order to effect an association between two endpoints that bind different
interfaces, is wrong.

Amy!
-- 
Amelia A. Lewis
Architect, TIBCO/Extensibility, Inc.
alewis@tibco.com
Received on Thursday, 15 January 2004 11:57:09 GMT

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