Given the problem of change, the next thing is to find out the exact mechanism to follow to version control the services. In fact, we have already seen one way, which is the generic string formatted messages approach, but as discussed, this may not be the best available method. We will now look into multiple options available for service versioning.
One important question to answer in service versioning is the level at which we have to version control. By level we mean whether at the whole service interface-level or at the individual service method-level. Perhaps this question is out of context because when we speak on SOA and its constituent services, we always means services which are coarse grained, which are never individual fine grained method invocations. In other words, we always speak about "transfer fund", "authorize credit", or "validate service" request in SOA, but not fine grained methods such as "update balance cell in account...