Java Reference
In-Depth Information
Granularity
Granularity
Your service will participate in an evolving landscape of many services. Getting the proper
level of granularity is key to ensuring that you can reuse a service, that you can expose it
successfully to your business partners, and that your security constraints will be appropri-
ate.
Contract
Within your model, identify what elements you will need in your overall service contract.
Some of these may be direct attributes of the service, and others may serve as metadata
that you make available within the context of WS-MetadataExchange. Some elements will
be non-functional, and some can be declared and enforced within the sorts of SOA runtime
environments offered by commercial vendors.
Process
Process analysis is a discipline all its own, probably unfamiliar to many OO developers.
Because business processes can be represented as services, and because business pro-
cesses will make use of services, it's important to understand the IT world from this per-
spective. A real discussion is beyond the scope of this topic, but if you have business ana-
lysts and Lean or Six Sigma professionals in your organization, they can be a very valu-
able resource.
Consider these things when you are modeling a new service, in addition to the object-oriented
analysis skills you bring to bear.
NOTE
I only touch on the subject of SOA modeling briefly here. As mentioned earlier, the ideas surrounding
SOA, service modeling, process modeling, and so on fill entire topics. This chapter is intended to
give a grounding in some of the key concepts. If you are interested in SOA modeling, you might
check out Michael Bell's book Service-OrientedModeling:ServiceAnalysis,Design,andArchitec-
ture(Wiley).
Service documentation
Document the service candidates you elicit with an enterprise view. Do this as an iterative
process, using a standard format, in order to visualize your service-enabled enterprise. This
documentation must ultimately be composable into a larger enterprise service catalog.
Be careful of attempting to model your entire business up-front. Circumstances are likely to
change before you complete such an effort. It is reasonable to take a more modular approach
