Making decisions about interface granularity can be very important in service-oriented design. Granularity can have a significant impact on performance and other concerns. Usually, a service interface contains more than one operation, and the operations of a service should be semantically related.
Fine-grained service operations offer greater flexibility to service consumers but lead to more network overhead, which could reduce performance. The more coarse-grained service operations we have, the less flexible they are, although they do reduce network overhead and could therefore improve performance.
Software architects should seek to find the right balance between the number of services and the number of operations in each service. You do not want to group too many operations into a single service, even if they are semantically related, because it makes the service too bulky and hard to understand. It may also increase the number of service versions that will need to be released going forward, as parts of the service need to be modified. However, if your service interface is too fine-grained, you may end up with an unnecessarily large number of service interfaces.