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Subject: RE: [soa-rm] Groups - Rough notes taken during the last ebSOA meeting. (ebSOA-Elements.pdf) uploaded
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 | | -- | *********** | Senior Standards Strategist - Adobe Systems, Inc. - | http://www.adobe.com Vice Chair - UN/CEFACT Bureau Plenary - | http://www.unece.org/cefact/ Adobe Enterprise Developer | Resources - http://www.adobe.com/enterprise/developer/main.html | *********** |
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