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

Chapter 5. Guidelines 122ViewFrontendProcess AbstractionProcess AbstractionInventory EndpointsInventory EndpointsSchemaBasic ServicesPolicySchemaBasic ServicesPolicyUtility+ Frontend=UtilityResourcesResourcesEntityEntityRulesRulesStateStateFigure 5.12: Migration step 12Applied SOA pattern: UI mediatorHow to: Provide continuous feedback to users. The feedback includes informationabout progress of an ongoing process, responding to exceptionas well as displaying forms in order to acquire additional information fromthe user [32]. Literature provides two possible realizations of UI mediatorpattern [32]:(a) A mediator service – requires a permanent binding of client applicationto mediator service for process duration. This kind of mediatorservice contains own logic that decides when and how often interactwith client.(b) A mediator service agent – a service agent is an implementation ofevent driven logic. Events are lunched for instance after each step ofthe process like service invocation. The pattern does not specify howan event can be lunched and intercepted by the agent. The patternstates that an agent has to be stateful in order to continuously notifyclient application. UI–Mediator related code can be found in alreadymigrated Frontends and Controllers of the migrated system. It is alsoworth to revise documentation of the migrated system.5.3 Project for migrationThe previous section presents guidelines for migration in order to their application.The guidelines are theory. There is a need of illustration how to apply them