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Re: Reference requirements

From: Steve Graham <sggraham@us.ibm.com>
Date: Thu, 21 Feb 2002 10:41:52 -0500
To: www-ws-desc@w3.org
Message-ID: <OF1ACFF8A7.1989BE74-ON85256B67.0055A593@raleigh.ibm.com>
On a related note, some work has been going on in the Grid computing space
to define an approach to instance-based Web services [1][2].

In the Grid services specification [2], we define the notion of a handle
and a reference.  Handles are permanent identifiers to a Grid service
instance.  References are protocol dependent, they may be a CORBA IOR or
maybe a WSDL document (depending on the protocol used to request the

A handle is currently a URL that contains both location information of a
mapping service (a place where handle can be used to obtain a reference)
and an instance id part to identify the service instance itself.

Please check these references out and lets discuss.  The work we are doing
in Grid services will co-evolve with the work going on in this working
group.  In an ideal world, many of the requirements on Web services we have
asserted in these papers would be folded into the base Web services work.

[1] http://www.globus.org/research/papers/ogsa.pdf
Steve Graham
(919)254-0615 (T/L 444)
Emerging Technologies

                      Mukhi/Watson/IBM@        To:       Paul Prescod <paul@prescod.net>                                               
                      IBMUS                    cc:                                                                                     
                      Sent by:                 Subject:  Re: Reference requirements                                                    
                      02/20/2002 11:24                                                                                                 


Returning a specialized URI for an instance sounds like an excellent idea;
however, I would take it one step further: why not return a specialized
WSDL? That gives you flexibility in terms of allowing the instance to
describe a binding too - which means you could ask a "factory service" for
an instance that offers some set of port types, and the factory would come
back to you with a WSDL (with port type definitions omitted and possibly
bindng omitted too - these would be imported so it would still logically be
a complete service description). The advantage of doing this over a URI is
that a URI isn't self-contained - I can't send you my service URI unless
you know everything else (the port type, binidng details). Of course
exchanging WSDLs is more heavyweight (even though in most cases the WSDL
may not contain more than <import...> and <service...> elements), but maybe
there is room for both alternatives? For my part, I think using WSDL itself
as a service reference makes more sense.


                      Paul Prescod

                      <paul@prescod.net        To:       www-ws-desc@w3.org

                      >                        cc:

                      Sent by:                 Subject:  Re: Reference


                      02/19/2002 03:07


Anne Thomas Manes wrote:
> Systinet WASP supports remote references using a header element to
> the instance id.
> Anne Thomas Manes
> CTO, Systinet

That's great. Can we standardize it?

Even better...why not combine the endpoint URI and the instance ID
somewhat like this:


I have other ideas beyond that but I'll let that one sink in. If you do
that then voila you've made it easy for every instance to be an endpoint
and all you need is a WSDL for it. Which puts the ball back in WSDL's
court. You need a way to say that the return value of a method will be a
URI like that and declare the WSDL that goes with that

 Paul Prescod
Received on Thursday, 21 February 2002 10:42:33 UTC

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