Its very important to use proper service identification techniques to identify services in an portfolio. In fact, service identification should be the first step in your service lifecycle management process.
Jotting down some of the techniques that we have been using for identifying services:
- Domain decomposition approach - Look at the high level business entities and create entity services for them.
- Top down BPM driven approach - Start from the business processes and divide them into sub-processes. Each business process consists of tasks & activities, that would orchestrate between different service components.
- Business Goal driven approach - Derive services from business goals. Decompose the business goals into a set of services that would help satisfy the business goal. Provide tracability between business goals and IT services by a Goal/Business Service matix.
- Existing systems - Service wrappers are created on existing systems - to surface them for orchestration in a business process or a composite service. This technique may not be appropriate if the existing IT landscape is not aligned with business goals.
- UI driven approach - Identify/discover services based on the user interface requirements. UI technologies such as Flash, Silverlight, Ext-JS directly call JSON/REST services on back-end application servers.