----- Original Message -----
From: "Mike Edwards" <[EMAIL PROTECTED]>
To: <tuscany-dev@ws.apache.org >
Sent: Wednesday, November 29, 2006 7:07 AM
Subject: Re: Pass-by-value support for remotable interfaces
> Raymond,
>
> First point I need to make is that just because two components are in
the
> same composite does not mean that they are automatically running in the
> same VM or even the same operating system process. Composites can span
> components running on different nodes (node = machine and/or o/s
process).
>
Good catch.
> Consider a composite which had component A implemented in Java and
> component B implemented in C++. Not likely that they would run in the
> same runtime process (certainly not with the current Tuscany runtime).
> This is perfectly OK as long as any interface between them is
"remotable".
>
> Second, more general point to make, is that there may be implied
semantics
> for the interface that depend on the binding used to connect the
reference
> to the service. Consider the case where the interface involves an
> operation with a message having two references to the same object.
> When
> this is sent from consumer to provider (say), does the provider receive
2
> separate copies of the object or just one - assuming the consumer
started
> with only 1.
>
> The answer is "it depends on the binding" - RMI-IIOP says there is only
1
> copy. Web Services says there are 2 copies...
>
> I don't think that SCA can hide these subtle differences, much though
> we
> may like to do so. However, what we must guarantee is that the
behaviour
> matches the binding type - if the internal wire uses binding.ws, for
> example, then we provide Web services semantics. This must be true for
> any optimisations we may like to use in the case where both ends of the
> wire are in 1 process - since for a remotable interface this proximity
is
> "accidental" and could be changed by a subtle change in deployment.
>
> That leaves open what to do in the case of binding.ws. We may need a
way
> for the composition to indicate the type of semantics required - or we
> could default to one form (eg Web services...)
>
Should this be clarified by the SCA spec on pass-by-value?
>
> Yours, Mike.
>
> Raymond Feng wrote:
>> Hi,
>>
>> I'm talking about the following:
>>
>> componentA.reference --> componentB.service1
>> non-SCA client --> componentB.service1
>>
>> In the cases above, componentA and componentB are in the same
>> composite
>> (in the same VM). Both the service and reference are declared with a
>> remotable interface. We need to have an interceptor to deal with the
>> pass-by-value.
>>
>> For the following wirings:
>>
>> .. --> composite.reference
>> composite.service --> ...
>>
>> I assume the binding implementation for the composite
>> reference/service
>> will handle the pass-by-value naturally over the transport.
>>
>> Thanks,
>> Raymond
>>
> <snip>
>
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