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

[Rich Thompson <richt2@us.ibm.com>]

I would agree with this argument for
the use case of someone trying to simulate a Service Group as a WS-Resource.

I would not agree for the case where
the WS is an interface to a component that needs handles to various (existing)
stateful entities in order to process the messages declared in its WSDL
(don't think of WSRF messages, think of a getMarkup message to a portlet).
The choices are: 1) Require such a WS-Resource to physically wrap these
entities into a single resource which can then be mapped to the WS-Resource
or 2) Allow the WS to logically wrap the existing entities as a single
resource. I don't see why the WSRF spec should be making this choice for
the architect designing the WS. From the protocol and client points of
view, it has to appear as if there was a single resource ... how that view
is generated is an issue properly left to the WS implementation.

Rich

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

10/16/2004 04:25 AM

To	Tim Banks <tim_banks@uk.ibm.com>
cc	wsrf@lists.oasis-open.org
Subject	Re: [wsrf] WS-RAP; section 2.3 - WS-Resource definition

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
     Hayes Park Central
     Hayes End Road
     Hayes, Middlesex  UB4 8FE

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