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

Chapter 2. Related Work 274. Mediator –mediates between Resource Layer and Entity Layer. The purposeof the layer is to manage business transactions, enforce business rules,instantiate business objects in Entity Layer and manage the memory cacheof the application.Depends on: Resource Layer, Entity Layer5. Entity –represents all the business objects within the application.Depends on: Independent6. Resources –mediates between application and data sources. The source canbe a database, service or other external entity containing required information.Depends on: External ResourcesThe pattern fits well to for business solution and as the business solutions becomea subject of integration. The integration presented by L. Maciaszek aims atintegration with Service Oriented Architecture. The pattern is modernised inorder make the integration possible. The modernisation of the pattern is namedPCBMER–U (Utility) and introduces three new elements into the pattern(seefigure 2.3).1. Broker –is a message broker2. Orchestration –encapsulates and executes a new business logic (see 4.3.2 formore information)3. Service Registry –is responsible for service discovering and depends only onmediator.The modification seems to have some contradiction. The first is that accordingto description, Registry depends on “utility’s business logic in Mediator” [52]what in fact is quite interesting because Mediator Layer does not depend onController Layer, consequently Mediator layer is not ”aware” of Controller layer.Registry may not discover higher level services located in Controller. The nextpotential contradiction is where Orchestration is introduced. According to figure3 in [52] Controller depends on Orchestration what seems to be against roleof Orchestration, because in fact Orchestration / Process Services depend onunderlying services what in this case may mean that Orchestration depends onservices allocated in Controller layer. The last contradiction refers to the figure 3and the description. Description says that Broker and Orchestration depend onlogic in Controller Layer while the dependency in the picture is opposite. Thesame situation refers to Mediator Layer and Registry.