In the SOA architecture used in this organisation, there are some more terms which need to be explained to understand the solution presented in the next chapter.
A Service is a functional entity with an interface and internal implementation. The interface defines the request message to invoke the service and the response message which contains the result from the invocation. The internal implementation defines how the response is constructed from the request message. Figure 2 shows a simple example of a back end adapter service with a Start and End node and an invocation of another service “BE Sample”. Every step in the service design can generate an error which is described separately.
- Composite Service
A Composite Service is a service without a direct communication to an external system. It combines the functionality of several other services into a single service. An example of a Composite Service is shown in Figure 3 which asynchronously invokes a back end adapter service (BEA Sample).
A Chain is a combination of systems and services which together provide a consistent set of functionality. Usually, such a chain is the result of a (successful) project. An example of a chain is Number Portability which is a combination of all services related to the functionality of porting a mobile number from one operator to another operator.
A Component is a combination of related services which can be deployed together. An example is the set of back end adapter services which all communicate with the same single back end system.