muSOAing for 4/16/09

The next big challenge for any SOA implementation is services modeling. There is a lot of leg work and planning that needs to be done before you embark on this important task. Ask yourself these set of questions,

– How many existing APIs am I looking at: Do an audit of your existing set of core business APIs that you want to expose
as services both internally and for consumption by trading partners

– SLAs for services: Who is the caller and what are the SLA requirements for these services. Beware that services are
sometimes quite notorius for throwing your SLAs out of whack so tie this down very well right from the beginning.

– Granularity for services: One of the key factors that will determine this is your SLAs. Another factor is whether this will
be a shared service. Another point to note is, services can be composed so whether they are coarse grained or fine
grained will at times not matter if BPM is a key part of your SOA strategy. You an always compose coarse grained
services but you are walking a tightrope here so don’t go overboard. Always do small POCs to validate your findings
instead of going by what you see on paper.

– Services design: Any IT shop will have to deal with two modes of services development. One is to develop services from
scratch and the other is service enabling existing APIs through wrappers. We will get into the gory details of this in future
posts but there you can run into debates about pure web services vs EJB wrappers etc. How do you decide.

– Services Framework: How do you build and deploy your services. The frameworks for the client and server side of
services. This is another very interesting topic and we shall get into the details in future posts.

– Services Security: This is another very important aspects and there are several things to consider. It will primarily be
driven by your overall corporate Security Policy. It can be a federated model or a decentralized model.

Once you have services in place we can get into the details of other aspects such as Governance, Monitoring, Versioning etc.

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