Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definition

[David Snelling <David.Snelling@UK.Fujitsu.com>]

Tim,

Well put. I was thinking that this would be an easy thing to add. I was 
wrong. The solution to targeting many WS-Resources with the same 
message is to use a Service Group extended with an iterator. This could 
be added as a new operation on SG itself or as something added by the 
developer using SG to create collections that behave in this way.

Bryan: Is there an issue for adding iterator to SG? I have heard it 
discussed several times now.

On 7 Oct 2004, at 15:09, Tim Banks wrote:

>
>
>
>
> Dave,  (and Rich)
>
> You said:
>
>> If I have a WS and a bunch of resources, I have a set of WS-Resources
>> with a one-to-one correspondence to the resources. Because all the
>> WS-Resources share the same WS they can respond to the operations.
>
> If the resources are independent they may respond differently to the 
> same
> operation. Some may respond with a fault; how are the different 
> responses
> combined? What is the client to make of this? So, it may work in some 
> cases
> (perhaps you have some in mind that you could describe) but it isn't
> generally applicable because the interface of the components isn't the 
> same
> as the interface of the aggregation. You can define a new interface 
> for the
> aggregation (probably with some rather vague fault messages in the 
> general
> case) but that establishes a new kind of behaviour for the aggregate
> resource (singular).
>
>
> Regards, Tim Banks
> IBM TP Architecture & Technology. Hursley, UK.
> Phone: External +44 1962 815639, Internal 245639
>
> David Snelling <David.Snelling@UK.Fujitsu.com> wrote on 06/10/2004
> 09:03:33:
>
>> Folks,
>>
>> This issue has come up in other discussions I have had, particularly
>> with folks less enthusiastic about WSRF. Put generally ...
>>
>> If I have a WS and a bunch of resources, I have a set of WS-Resources
>> with a one-to-one correspondence to the resources. Because all the
>> WS-Resources share the same WS they can respond to the operations.
>> Rich's question (and that of others) is, can I drive the same 
>> operation
>> on all WS-Resources at once?
>>
>> Answer 1: Yes, create a new Disambiguator that refers to the whole
>> collection. Steve pointed to this option.
>>
>> Answer 2: Wrap the set of WS-Resources in a ServiceGroup and drive the
>> operation on all WS-Resources through an iterator operation on the
>> ServiceGroup (NB: such an iterator has yet to be proposed for
>> ServiceGroup).
>>
>> Answer 3: Allow multiple Disambiguators in a single message. To use
>> embodiment 1, create an EPR for the collection that looked like this:
>>
>> <wsa:EndpointReference>
>>
>> <wsa:Address>http://localhost:8080/axis/services/UnicorePort</wsa:
>> Address>
>>     <wsa:ReferenceProperties>
>>        <ns1:ResourceDisambiguator 
>> xmlns:ns1="http://arcon.fujtsu.com/";>
>>        UnicorePort:E5623340-16DA-11D9-9A2A-C83D27C15A63
>>        </ns1:ResourceDisambiguator>
>>        <ns1:ResourceDisambiguator 
>> xmlns:ns1="http://arcon.fujtsu.com/";>
>>        UnicorePort:0035B930-16DB-11D9-9A2A-9A608286117E
>>        </ns1:ResourceDisambiguator>
>>     </wsa:ReferenceProperties>
>> </wsa:EndpointReference>
>>
>> The semantics would require that the client copy both Disambiguators
>> into the message and the service could interpret this as "Drive the
>> same operation on all the WS-Resources referenced by the 
>> Disambiguators
>> in the message."
>>
>> I kind of like this, but I have never been convinced by WSRF critic's
>> use cases. Possibly the WSRP use case is a strong enough one.
>>
>> Note: I don't believe this approach is as straight forward for the
>> other embodiments as the above.
>>
>
>
-- 

Take care:

     Dr. David Snelling < David . Snelling . UK . Fujitsu . com >
     Fujitsu Laboratories of Europe
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