RE: [soa-rm] Groups - Rough notes taken during the last ebSOA meeting. (ebSOA-Elements.pdf) uploaded

["Peter F Brown" <peter@justbrown.net>]

Surely "service oriented" implies a capacity to deliver a service whether
the service is actually initiated/used or not?
In other words, it must be *capable* of delivery: does that then imply a
messaging infrastructure? If you scream in an empty forest, have you
communicated anything? An old philosophical dilemma...

IMO, I would say that the message is not a required part of the RM but its
construction must be possible from and compatible with the RM. I think Frank
has a point, in distinguishing between operation (private) and effect
(public). It is the transition between the two that makes something a
service rather than just a process, and that transition must be possible
even if not actually invoked

Peter

| -----Original Message-----
| From: Duane Nickull [mailto:dnickull@adobe.com] 
| Sent: Tuesday, March 29, 2005 6:54 PM
| To: Gregory A. Kohring
| Cc: soa-rm@lists.oasis-open.org
| Subject: Re: [soa-rm] Groups - Rough notes taken during the 
| last ebSOA meeting. (ebSOA-Elements.pdf) uploaded
| 
| Gregory:
| 
| I would never dispute that a message is required during 
| runtime in a concrete architecture, but still do not concur 
| that it is a necessary part of the reference model.  If I 
| build something and want to say it is "service oriented", it 
| must have a service.  That service has a binding implicit by 
| its existence.  The question we should probably answer is "if 
| it is architected with X ( X is a placeholder for the elements of 
| the reference model), is it service oriented"?   Our job 
| should then be 
| to figure out what X is.  If I am an application builder (not 
| infrastructure), and I build one application and I want it to 
| be service oriented, it should have an ability to receive a 
| service invocation (probably via a message), but do I have to 
| have a message present for me to state my application is 
| built using service oriented architecture?
| 
| In the coffee shop example, writing an architecture for a 
| coffee shop that is oriented towards providing services makes 
| it service oriented, even if no one has entered the coffee 
| shop and started the dialog.  More comments inline:
| 
| Gregory A. Kohring wrote:
| 
| >
| > I think you have your analogy a little bit confused here. 
| It is not a 
| > question of whether a car has to be driven before it is 
| called a car, 
| > but whether a car without wheels is called a car. It would 
| seem to me 
| > that a service without "message" is not a service.
| 
| The concept of service includes the ability to be bound to 
| and invoked, but the message itself is an instance object 
| doing such.  The binding capability is a core part of a 
| service.  Perhaps we are stuck on semantics?
| 
| >
| > Go back to the coffee shop example. The service a coffee 
| shop offers 
| > has a well defined  message exchange protocol which works 
| the same the 
| > world over. Basically it involves the consumer placing an 
| order, the 
| > server  confirming the order, then the server requesting payment.
| > This is a very generic message exchange protocol which has 
| also been 
| > taken up by many online shops.
| 
| But for the coffee shop architect to state "this coffee shop 
| is service oriented WRT its architecture, does that 
| conversation need to actually take place?  IMO - the answer 
| is no.  It "offers" the well defined message exchange - this 
| is akin to the binding IMO.
| 
| > This is not the only possible protocol, you could demand a down 
| > payment before the consumer orders the service, in which case you 
| > probably want to rearrange your coffee shop so that people 
| have to pay 
| > before entering. (Or you make people put a down payment before 
| > browsing your online store.) Hence, the choice of protocol has an 
| > impact on how the service is designed.
| 
| There are still services with bindings.  Even if no one 
| enters the coffee shop, one could still assert the shops 
| architecture is oriented towards services.
| 
| Messaging protocols are definitely a part of any concrete SOA 
| and messages need to be present at runtime.  I am not 
| convinced that the concepts belong in a reference model however.
| 
| Would like to hear other points of view on this.
| 
| Duane
| 
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