• Operations and parameters
• The quality of documentation
• The degree of interdependence between service operations.
Moving a legacy application to SOA requires addressing these issues.
The granularity of a service is defined in terms of the number of service operations it should contain. An operation causes some business function, support function, or transaction to occur.
Granularity can be rated on a sliding scale from “fine-grained” to “coarsegrained.” A coarse-grained service contains multiple operations that perform pieces of complex business functions. A fine-grained service is a single operation that carries out the entire function. Each type of granularity may or may not be appropriate as a service in your organization. As with everything else in the world of IT, it depends.
How do you decide what constitutes a service?
There are at least five factors to consider when designing services:
• Number and type of operations