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

Chapter 3. Architectural Patterns 51chronous logic of the systemSynchronous Service– represents logic of the system executed in a synchronousmannerAsynchronous Service Layer– contain low–level elements executing asynchronouslogic of the systemAsynchronous Service– represents logic of the system executed in an asynchronousmannerQueueing Layer– contains element mediating between Synchronous andAsynchronous layersQueue– a mediating element from Queueing LayerExternal Event Source– generates event processed by services from AsynchronousLayerRelationships– - Services from each layer can cooperate with other servicesfrom the same layer. They can also invoke Queue that serves as a messagestore. External Data Source can invoke only services from AsynchronousLayer (see figure 3.15 ).Sync Service 1 Sync Service 2 Sync Service 3 Synchronous Service LayerQueueQueueing LayerAsync Service 1Asynchronous Service LayerExternal Event SourceFigure 3.15: Example usage of Half–Sync Half–Async pattern11. Shared RepositoryOverview– provides solution for problem of passing large amount of databetween elements of a system. The pattern reduces additional overhead andperformance drop.ElementsRepository – is a core element of the pattern. It is meant to store, maintain