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Subject: Re: [soa-rm] another possible SOA diagram (revised)
Fank, I like the idea of importing an RM for "resource". Can you recommend one we can use? Greg Francis McCabe wrote: > Aaarrrgh .... > > This was a big debate in the Web Services Description WG (WSDL 2.0). > About there being a resource behind the service. > This is the entirely spurious but very seductive idea of the one true > resource™. > > For *some* people, it is right and appropriate for their application > to think of the one true resource represented by their service. But it > is certainly not the general case; many services have the character of > filters (e.g., unit conversion services, ATM machines, encryption > services) which are not primarily concerned with their own resources. > Other services are all about *combining* resources e.g., selling and > delivering books, subscription and notification services. > > From other perspectives (e.g., service management, policy > enforcement, deployment, etc. etc.), the service itself *is* a resource > that has an existence independent of other resources it manipulates. > For example, resources are *things* that can be bought; and a service > certainly meets that criteria. > > Personally, I believe that all of this stuff on resources does not > belong in a SOA RM; the reason: resources have their own modeling and > we can simply layer on top of the concept. > > Frank > > > On May 23, 2005, at 3:28 PM, Ken Laskey wrote: > >> Greg - see below >> >> At 02:33 PM 5/23/2005, Greg Kohring wrote: >> >>> Sorry, but this diagram has a few problems. >>> >>> 1) A "Service Interface" is a concrete representation of some of the >>> constraints detailed in the contract; i.e., it is too concrete for >>> being mentioned so prominently in a reference model. >>> >> >> The service interface is more a representation of the data model than >> a constraint, and I am referring to an unambiguous prescription of >> the interface and not the implementing code. A such, I'd see it no >> more concrete than the specification of a policy. >> >> >> >>> 2) It is the service that is the resource, not the service description. >>> >> >> It has been a while since I read WSA, so my apologies if my use of >> the terms is different. I see the resource as being something that >> provides something I need, whether data or processing. I see the >> service as a means to gain access to the resource but the resource >> exists independent of the service. Many services may access the same >> resource, e.g. for different guaranteed quality of service. >> >> >>> While it is certainly true that every service is a resource, the >>> converse is not true. >>> >> >> Again, this may go against past WSA work but I do not consider a >> service to be a resource. It is one means of accessing a resource. >> >> >>> You might even define an SOA is an architecture >>> in which all resources are either themselves services or can only be >>> accessed through services (i.e., they are part of the service's data >>> model). Therefore, if your architecture only consists >>> of services, you need not mention resources explicitly. >>> >>> -- Greg >>> >>> >>> Ken Laskey wrote: >>> >>>> The resource is the implementation that in many cases was created >>>> to satisfy needs outside the SOA and only becomes part of a SOA in >>>> the same way that any software package becomes part of your >>>> computer. Opacity says you know there is a resource but the only >>>> thing you know about it is what is exposed through the service >>>> description. >>>> Attached is a very quick attempt to include in Duane's last diagram. >>>> Ken >>>> >>>> On May 23, 2005, at 9:18 AM, Christopher Bashioum wrote: >>>> >>>> >>>>> OK - that makes sense. In fact, I remember a book on SOA >>>>> patterns that >>>>> talks about this (forgot the title, but the author is Paul Monday). >>>>> In his >>>>> view, what you are referring to as a service he would refer to as an >>>>> architecture adapter. I.e., the implementation (resource) is done >>>>> in a >>>>> particular architural style. In order to adapt that >>>>> implementation to the >>>>> SOA architectural style one would us an architecture adapter. >>>>> (at least >>>>> that's what I got from his book - I may have misunderstood). >>>>> >>>>> So ... A second question for you - do you think we need to add a >>>>> resource >>>>> box to the diagram that Duane sent out? If so, what would be the >>>>> relationship between the resource and the service? >>>>> >>>>> -----Original Message----- >>>>> From: Ken Laskey [mailto:klaskey@mitre.org] >>>>> Sent: Monday, May 23, 2005 9:11 AM >>>>> To: Christopher Bashioum >>>>> Cc: 'SOA-RM' >>>>> Subject: Re: [soa-rm] another possible SOA diagram (revised) >>>>> >>>>> The resource is the real thing out there that provides a >>>>> capability -- >>>>> in the 07 draft, there is a discussion of data resources vs. >>>>> processing >>>>> resources. In general, a resource does not have to be service- >>>>> enabled. >>>>> However for SOA, the resource must have (we can continue to debate >>>>> this) a service interface that is one of the things published through >>>>> the service description, and that service interface is how you >>>>> connect >>>>> the resource to the underlying service infrastructure. Additionally, >>>>> the service infrastructure has to provide certain TBD capabilities >>>>> and >>>>> likely overlaps but is not necessarily the same as what is often >>>>> termed >>>>> an ESB bus. >>>>> >>>>> Ken >>>>> >>>>> On May 23, 2005, at 8:53 AM, Christopher Bashioum wrote: >>>>> >>>>> >>>>>> Ken, >>>>>> >>>>>> Intuitively, I like this one. One question: how is the resource >>>>>> different >>>>>> than the service? Also, for the TC to use, we may be able to >>>>>> identify >>>>>> the >>>>>> essential elements with a * and then the other optional elements to >>>>>> show >>>>>> where they fit (for example, I see basic logging as non- >>>>>> essential, but >>>>>> this >>>>>> diagram shows where it fits). >>>>>> >>>>>> The diagram may not show up in the actual RM doc, but it may be >>>>>> useful >>>>>> for >>>>>> us as a conceptual model. >>>>>> >>>>>> -----Original Message----- >>>>>> From: Ken Laskey [mailto:klaskey@mitre.org] >>>>>> Sent: Monday, May 23, 2005 12:43 AM >>>>>> To: 'SOA-RM' >>>>>> Subject: [soa-rm] another possible SOA diagram (revised) >>>>>> >>>>>> I played with the ideas in the sketch a bit more. As noted in the >>>>>> previous email: >>>>>> >>>>>> I would not necessarily advocate it being used instead of the >>>>>> one Duane >>>>>> drew but given I had it, I thought I'd pass it around for comments. >>>>>> The 3D presentation may make it look too concrete but I was >>>>>> looking for >>>>>> a way to show there was something SOA I was building services on and >>>>>> there could be any number of services. Note a resource could be a >>>>>> registry but even that would be exposed through services and have >>>>>> metadata. >>>>>> >>>>>> Ken >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> ------------------------------------------------------------------- >>>>> ---- - >>>>> ------------------ >>>>> Ken Laskey >>>>> MITRE Corporation, M/S H305 phone: 703-983-7934 >>>>> 7515 Colshire Drive fax: 703-983-1379 >>>>> McLean VA 22102-7508 >>>>> >>>
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