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Subject: RE: [soa-blueprints] Anti-Blueprints - Number of services
All: I still have problems with the "number of services is a measurement of whether something is a pattern/anti-pattern for SOA" conversation. If you agree that the internet is a large SOA, it has more than 10,000,000 services and I do not think that anyone would state that is not an SOA due to the large number of services. I would not be willing to state that the internet is architected errantly since it has too many services. Number of services has no static bearing on good vs. bad design IMO. The requirements vary specific to scenario and YMMV. Some thoughts on what may not be SOA (*thoughts only) 1. A service that is orphaned and has no associated mechanism for being discovered by any consumer is probably not SOA, even though it is a service itself. One of the core tenets of SOA is that concrete services must have some mechanism to declare they exist and are available and to communicate such to potential consumers. A service availability and discovery concept is in the core reference model (*EDITORS DRAFT only). 2. A service with a set of metadata too slim to provide a potential consumer with the information and/or pointers to information it requires to make a service invocation request is not SOA. This may include many mechanisms including out of band human-to-human contact to figure out more intricate details. A service discovery concept is in the core reference model. 3. A set of multiple services that functionally duplicate each other and one of the services is not used by any active or planned future consumer MAY be a poor practice, but is still probably SOA. 4. A service that does not have a mechanism to allow a potential consumer to discover its policies may not be SOA. Even if a service has no specific policies, that is still a conceptual policy. 5. A set of services that advertise or claim they act on a specific resource but in fact do not do anything, are likely not SOA. 6. A service that has no interaction possible is likely not SOA. 7. An always on synchronous socket from one physical endpoint to another may not be SOA. Not sure how to qualify this or if it is relevant to the price of tea in China... So what! While this is an interesting conversation, I also think it may detract from the work of building the following items: 1. A metamodel for expressing architectural blueprints; and 2. A catalog of SOA blueprints and a system for locating ones that are applicable to a specific scenario. Duane
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