- Service boundaries are absolute they "how" techniques can
- Alter internal state
- Invoke external services
- They cannot
- Contain activities that are internal to another service
In this way there is no Process to Service mapping, but Service acts as a container for process, and process is the mechanism via which the capabilities of that service are realised.
The next challenge is how to model these processes within a service context. First challenge is the current tools aren't set up to do this, they like to model process as the ultimate goal and they haven't yet got to modelling business as services. This means we have to do a few work arounds. The first option is to use service models, as per the methodology, to indicate the orchestration of services to deliver capability.
If using BPMN rather than modelling the whole end to end process model the overall execution process (the numbers on the diagram) and model EACH of the invocations as individual process. Do NOT try and model this has a massive process with lots of swim lanes. This will make the transition to services harder as these process models will cross service boundaries within one process model. The challenge is to be able to create these end-to-end processes as views rather than as models, again the tools don't really help here at the moment as they are process oriented rather than service oriented.
All this is at the level at which process is a series of activities. This isn't the only level at which process and service need to interact, the other level is where process describes a broad area like "buy" which means all of those processes releated to buying. At this level the terms service and process can be reasonably interchangable because they both are used to describe broad areas. The key therefore is to identify the points at which process stops being about broad areas and about stringing activities together.
In an enterprise model this often occurs between level 2 and 3, but this isn't a fixed point so you need to be careful.
So in summary : Broad area process is pretty much interchangable with service, activity and orchestration processes are contained by services and implement capabilities of those services.