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Re: "OO" features of WSDL 2.0

From: Jacek Kopecky <jacek.kopecky@deri.org>
Date: Tue, 14 Feb 2006 12:25:29 +0100
To: Paul.Brebner@csiro.au
Cc: www-ws-desc@w3.org
Message-Id: <1139916329.3938.20.camel@localhost>

Hi Paul,

AFAIK, interface extension is intended as purely syntactical reuse
mechanism, because WSDL does not attribute any meaning to interfaces or
operations beyond the assignment of MEPs and concrete data schemas.

However, the operation safety extension allows one to claim an operation
is safe, which significantly restricts the potential meaning of that
operation. This indicates that there is a direction in WSDL use that
would actually ascribe concrete meaning to interfaces or interface
operations, and in fact the W3C proposes to work on a continuation of
WSDL-S [1]. This may lead to interface or operation-based discovery and
similar tasks, extending the usefulness of interface extension, so to
speak, and the usefulness of the information that a service implements a
given interface.

As for service instances, WSDL assumes that one service may provide
multiple endpoints that are, in some way, gateways to the same thing.
There are no other standard relationships between services, nor are the
terms "inheritance" or "service instance" mentioned in WSDL. The spec
doesn't intend to imply such terms or concepts either, they are to be
handled by extensions.

Hope it helps,

Jacek

[1] http://www.w3.org/Submission/2005/10/

On Sun, 2006-02-12 at 23:33 +0000, Paul.Brebner@csiro.au wrote:
> Hi,
> 
>  
> 
> There are some aspects of WSDL 2.0 that have an OO flavour, and Ióm
> wondering what the motivation, scope/limitations, and expected use of
> these are. For example (related to inheritance, extension and service
> instances):
> 
>  
> 
> Is it possible to model and expose arbitrary service inheritance
> relationships? Other service relationships? Can these be applied to
> abstract services, concrete services, or instances of services?
> 
>  
> 
> Does interface inheritance apply only across same
> service/implementation of a service?
> 
>  
> 
> What mechanisms are used to model service instances? (in the stateful
> or grid sense)
> 
>  
> 
> Can services have properties? Values? (run-time) State? (c.f. say OGSA
> SDEs)
> 
>  
> 
> Regards,
> 
>  
> 
> Paul
> 
> --
> 
> Paul Brebner www.ict.csiro.au/staff/Paul.Brebner
> Senior Software Research Engineer 
> CSIRO ICT Centre www.ict.csiro.au
> Australian National University, Canberra, Australia 
> +61 2 6216 7062 
> 
>  
> 
>  
> 
> 
Received on Tuesday, 14 February 2006 11:25:33 GMT

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