Migration of a Chosen Architectural Pattern to Service Oriented ...

Chapter 5. Guidelines 109ContextAn application requires access to external resourcesForces(a) There are many services that require access to external resourcesSolution Canonical Resources identifies and standardizes resources acrossthe company. A term resource refers to databases, activity managementsystems, state deferral mechanism or other resource like for instance publicservices. Separation of access to external resources grows in importancewhen an application is not small, because in small application access toexternal resources is rather centralized.Result Contextexternal resources.The system has standardized and centralized access to7. Name Entity AbstractionProblem Many business processes uses the same business entities. It isvery likely that the functionality is implemented several times in differentservices. This raises problems with maintenance and testability.Context An application is composed of business services performing operationson the same entities.Forces(a) Functionality provided by services cannot be implemented in otherservices(b) Business entities do not change too frequentlySolution Entity Abstraction introduces another layer into layered structure.The layer contains services performing operation on business entities.Result Context The application has some services performing operationson business entities.8. Name Rules Centralization