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Subject: RE: [sca-j] Java Callback Simplification Proposal


OK, I thought I had been clear, but obviously not.

Let's lay out what I think of as a classic Callback scenario:

ClientA  uses an anychronous callback provided by   ServiceB

the forward service interface has operations   S1, S2, S3
the callback interface has operations CB1, CB2, CB3
the interfaces are non conversational

and the following applies (stated as non-code metadata):

invoking S1 causes CB1 and CB2 to be returned (in that sequence) over some long period
invoking S2 causes CB2 and CB3 to be returned (in that sequence) over some long period
invoking S3 causes CB3 to be returned at some later point

So, I want to write ClientA to do the following:

1. invoke S1
2. when CB1 is returned from S1, invoke S2
3. when CB2 is returned from S1, note the result
4. when CB2 is returned from S2, if the result tallies with CB2 from S1, invoke S3
5. when CB3 is returned from S2, record it against S2
6. when CB3 is returned from S3, record it against S3

The essence of this requiement is that it is possible to get a callback message
whose original cause is not unique, but where the client needs to correlate the
callback message with the invocation it made.  

With a callback ID, I think the client can set the callback ID appropriately and
do the correlation.  Without a callbackID, how can I do it?

Yours,  Mike.

Strategist - Emerging Technologies, SCA & SDO.
Co Chair OASIS SCA Assembly TC.
IBM Hursley Park, Mail Point 146, Winchester, SO21 2JN, Great Britain.
Phone & FAX: +44-1962-818014    Mobile: +44-7802-467431  
Email:  mike_edwards@uk.ibm.com

"Jim Marino" <jmarino@bea.com> wrote on 13/02/2008 11:46:23:

> Hi Mike,
> Before I respond in detail to your comments, could you please
> enumerate the use cases you believe this proposal would inhibit,
> particularly from the perspective of having SCA infrastructure
> manage those interactions? Otherwise, I may not directly address
> your concerns.
> Thanks,
> Jim

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