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

[Duane Nickull <dnickull@adobe.com>]

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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Senior Standards Strategist - Adobe Systems, Inc. - http://www.adobe.com
Vice Chair - UN/CEFACT Bureau Plenary - http://www.unece.org/cefact/
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