Let's take a look at what implementing a new business process with SOA might look like.
Say you want to realize a new business process. You have the new business process on top and the existing backends, which might provide some basic business functionalities represented as services, on the bottom (see Figure 7-2).
Figure 7-2. Starting point for a new business process
Typically, you'll begin with a top-down decomposition to:
Decide which process steps are manual and which ones are IT-supported.
Separate the whole process into smaller chunks according to when they are performed and which systems are responsible for them.
Break down complex aspects into more manageable steps.
The result of this task (which might be called high-level design or solution design) is a rough idea of how the process should be performed in practice (see Figure 7-3). One important reason for this design process is to determine which IT systems are responsible for which parts of the process. Remember that we're talking about distributed processes. To go into further detail, you first need to identify the systems involved, so you know which people to discuss the details with.
Figure 7-3. High-level or solution design
An interesting question arises when services come into play: at which level ...