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Re: section 1, intro, for review

From: Paul Prescod <paul@prescod.net>
Date: Fri, 22 Mar 2002 14:18:10 -0800
Message-ID: <3C9BADA2.9A370660@prescod.net>
To: Don Box <dbox@microsoft.com>
CC: www-tag@w3.org
Don Box wrote:
> 
>...
> 
> I agree that the underlying data rep/type system of DCOM (ndr) and CORBA
> (cdr) didn't have clean extensibility or versioning built in. The data
> rep/type system of web services uses XML and XML Schemas, which have
> fairly well-understood extensibility mechanisms.

The common wisdom I have heard around web services is that once a WSDL
interface is published it does not change. Is your sense different?
Would the proxies generated by .NET gracefully handle new elements added
to an existing one? I would appreciate it if you could describe the .NET
web services versioning model or point me to an appropriate resource.

>...
> However, this ignores the fact that the community at large wants to
> build application-specific contracts. In the absence of XML/SOAP/WSDL,
> this means that every developer winds up building his own ad hoc type
> model and we have no chance of building infrastructure to cope with it
> in any sort of general way. SOAP et al give infrastructure more hooks to
> recognize what is going on in the network. Totally ad hoc hacks built
> using HTTP GET and query strings aren't the answer IMO.

I'm not sure to what you are referring. I think most people whether in
the REST camp or the Web Services camp acknowledge that
application-specific contracts will be strongly expressed in XML schemas
of some sort. The question is whether the documents conforming to those
schemas are subsumed into some kind of RPC infrastructure, or an HTTP
infrastructure or no infrastructure at all.

>...
> The SOAP infrastructure (framing using soap:envelope, extensibility
> using soap:header) are "defined uniform interfaces" that exist primarily
> to facilitate better intermediaries. The SOAP payload, however, tends to
> convey application-specific semantics, which are unavoidable if we are
> to allow developers to continue to innovate in this space.

We all agree that the payload must be allowed to vary. It does on
today's web as well! The question is what interoperability is bought
through the soap:envelope.

 Paul Prescod
Received on Friday, 22 March 2002 17:21:44 GMT

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