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Re: issue: optional parts in <message>?

From: Prasad Yendluri <pyendluri@webmethods.com>
Date: Wed, 01 May 2002 20:21:42 -0700
Message-ID: <3CD0B0C6.EB032FC0@webmethods.com>
To: "WS-Desc WG (Public)" <www-ws-desc@w3.org>
>Now what if "part" d is a "foreign" type, for example some ASN.1 doodad?
>Assuming we have agreed on an appropriate definition of the asn.1
>namespace.

I think this is big assumption that will not scale in a generic way. E.g.
any of the MIME types.

I guess it all boils down to, if an abstract representation as in "messages"
is really necessary. I think Sanjiva's note has enumerated the reasons for
this (http://lists.w3.org/Archives/Public/www-ws-desc/2002May/0022.html).

Regards, Prasad


Jeffrey Schlimmer wrote:

> It might be useful to compare two ways of describing a four-part
> message. This:
>
> <wsdl:message name="MyMessage" >
>   <wsdl:part name="a" type="xsd:string" />
>   <wsdl:part name="b" type="xsd:string" />
>   <wsdl:part name="c" type="xsd:string" />
>   <wsdl:part name="d" type="xsd:string" />
> </wsdl:message>
>
> Becomes this:
>
> <xsd:element name="MyMessage" >
>   <xsd:sequence>
>   <wsdl:element name="a" type="xsd:string" />
>   <wsdl:element name="b" type="xsd:string" />
>   <wsdl:element name="c" type="xsd:string" minOccurs="0" />
>   <wsdl:element name="d" type="xsd:string" minOccurs="0" />
>   </xsd:sequence>
> </xsd:element>
> <!-- implies this message declaration in WSDL -->
> <wsdl:message name="MyMessage" >
>   <wsdl:part name="parameters" element="MyMessage" />
> </wsdl:message>
>
> Note "parts" c and d are marked optional using the already-defined
> minOccurs facet in XML Schema.
>
> Now what if "part" d is a "foreign" type, for example some ASN.1 doodad?
> Assuming we have agreed on an appropriate definition of the asn.1
> namespace. This:
>
> <wsdl:message name="MyMessage" >
>   <wsdl:part name="a" type="xsd:string" />
>   <wsdl:part name="b" type="xsd:string" />
>   <wsdl:part name="c" type="xsd:string" />
>   <wsdl:part name="d" type="asn.1:doodad" />
> </wsdl:message>
>
> Becomes:
>
> <xsd:element name="MyMessage" >
>   <xsd:sequence>
>   <wsdl:element name="a" type="xsd:string" />
>   <wsdl:element name="b" type="xsd:string" />
>   <wsdl:element name="c" type="xsd:string" minOccurs="0" />
>   <wsdl:element name="d" minOccurs="0" asn1:type="doodad" />
>   </xsd:sequence>
> </xsd:element>
> <!-- implies this message declaration in WSDL -->
> <wsdl:message name="MyMessage" >
>   <wsdl:part name="parameters" element="MyMessage" />
> </wsdl:message>
>
> Note that the type of "part" d is indicated in both. In the latter,
> "part" d omits the xsd:type attribute, defaulting to any content.
>
> This does beg the question about the value of the wsdl:message
> construct. Why don't we focus WSDL on operational types and leverage the
> good work done on representational types by the XML Schema WG?
>
> --Jeff
>
> -----Original Message-----
> From: Prasad Yendluri [mailto:pyendluri@webmethods.com]
> Sent: Wednesday, May 01, 2002 2:52 PM
> To: Jeffrey Schlimmer
> Cc: WS-Desc WG (Public)
> Subject: Re: issue: optional parts in <message>?
>
> Jeffrey Schlimmer wrote:
>
> > XML Schema provides a rich, well-understood language for expressing
> > choices, sequences, optional, repeated, etc. constructs. It does not
> > seem like a good use of the WG time to re-invent such a mechanism.
>
> I don't believe it is re-inventing the entire mechanism. The spec allows
> multiple parts in a message for a reason (when this can be captured by
> the schema as well) these represent abstract parts coming from potentially
>
> different type-systmes and some perhaps well established schemas (e.g. a
> OAG BOD). The addition being called for is marking the parts optional at
> the
> message level.
>
> > Are there any interesting arguments against removing the message
> element
> > and making the operation within a port type point directly to an XML
> > Schema global element declaration?
>
> That would amount to doing away with the abstract types and other type
> systems and settling only on XMLSchema?
>
> > --Jeff
> >
> > -----Original Message-----
> > From: Sanjiva Weerawarana [mailto:sanjiva@watson.ibm.com]
> > Sent: Wednesday, May 01, 2002 1:18 PM
> > To: WS-Desc WG (Public)
> > Subject: issue: optional parts in <message>?
> >
> > <issue id="issue-message-parts">
> >   <head>Should the message part mechanism be extended to support
> > optional
> >         parts etc.?</head>
> >   In WSDL 1.1, a message can only be defined to be a sequence of
> parts.
> >   It is not possible to indicate that certain parts may be optional,
> >   may occur multiple times, etc.? Should we do that? Overlapping with
> >   XML Schema's mechanisms is an obvious concern.
> >   <source>Sanjiva Weerawarana</source>
> > </issue>
> >
> > Could we also start discussing this issue please?
> >
> > Sanjiva.
Received on Wednesday, 1 May 2002 23:19:58 GMT

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