Dennis, I posed a similar question to your last one and got some interesting comments:
http://www.innoq.com/blog/st/2006/08/21/whats_a_service_contract.html Best regards, Stefan On Sep 1, 2006, at 3:41 PM, dennis_djenfer wrote: > Hi folks, > > I'm trying to map a Reference Architecture to the OASIS SOA Reference > Model, however I've been put in a quandary by some of the definitions > in OASIS SOA-RM: > > 1) Service Description: "The service description represents the > information needed in order to use a service." [OASIS SoA-RM] > > My interpretation of SOA-RM is that a service description will > encompass documents like WSDL-files, XML-schemas, Policy document, > Service Level Agreements and so on. A service description is like a > map that points to all the information that a consumer needs to use > the service. That's fine for me, but it clashes with the term "Web > Service Description Language", which is not used for service > descriptions according to the SOA-RM definition (if you uses Web > Services). I guess we just have to accept this ambiguity. > > 2) Contract: "A contract represents an agreement by two or more > parties." [OASIS SOA-RM] > > Most people think about a WSDL-file as a contract, like in > "contract-first design", but is it really a contract? It is true that > the requirement work for a service in most cases has been done with > some specific consumers in mind, but after the service is deployed and > new consumers discovers the service, the interface to a service is > more like "take-it-or-leave-it". > > An SLA, on the other hand, is more like a contract that normally is a > negotiated with every consumer. > > 3) Policy: "A policy always represents a participant's point of view." > [OASIS SOA-RM] > > In many cases I would say that a WSDL-file is a policy-document if we > use OASIS definition. It's something that the service provider states > and the consumers has to accept. On the other hand, If a service state > that it will not be operational between 3 A.M and 4 A.M, that could be > a policy, but in many cases that is something that has been negotiated > between two parties, even after the service has been deployd. I could > very well imagine that a service provider will negotiate different > policys with various consumers that need different QoS. > > In that case a policy is more like contract according to the SOA-RM > definition. > > So, the problems I have with SOA-RM are: > 1) The well established term "Web Service Description Language" does > not actually define a language that is used for a service description > according to SOA-RM definition (well, this is a minor problem). > 2) Is a WSDL-file a contract or a policy-document? > 3) Does policy-documents always conform to the SOA-RM definition and > reflects one participants view or could it be a contract between two > parties? > > // Dennis Djenfer > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/service-orientated-architecture/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
