Service Operations and Overloading

The service operations are described as a combination of verb, modifier, and object, where the verb is the action or behavior, the modifier further describes or characterizes the object, and the object is an abbreviated name or description of the data. The scope of a service-oriented architecture (SOA) service is largely determined by a combination of the information (data) that is either manipulated by a service or returned to a requesting consumer in the response message and the operations that act on that information. The three primary types of services include data services, utility services, and functional services. The operations for each type of service should be defined by a standard set of verbs. The most common verbs used to describe service operations are those related to data services and are known as CRUD (create, read, update, delete). Other types of services also require a standard set of operations verbs. A utility service might include “Validate”, “Replicate”, or “Move” operations. The scope of a service and its relationship to supported operations are critical design considerations. A coarse-grained service exposes multiple operations to consumers. A fine-grained service only includes a single operation. A moderate-grained service will expose multiple operations but only those that have functional or data-related synergy. Another design technique allows for overloading service operations as elements and data values of the request message payload. This can be a powerful design pattern that helps to insulate existing consumers from change, when additional and new operations are added to a service. However, it also has disadvantages.