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Component Technology • • • • • objects versus components -- definitions interoperability requirements for distribution a simple workgroup application extending hush with CORBA Additional keywords and phrases: (D)COM, Java, CORBA, OLE, persistent objects, ODMG, workgroup Postacademische Cursus Informatie Technologie vrije Universiteit amsterdam Objects versus components Subsections: Definitions The technology matrix Component myths Postacademische Cursus Informatie Technologie vrije Universiteit amsterdam Definitions Component substitutability unit of independent deployment unit of third party composition no persistent state Object identity unit of instantiation (persistent) state encapsulation of state and behavior Postacademische Cursus Informatie Technologie vrije Universiteit amsterdam A software component is a unit of composition with contractually specified interfaces and explicit context dependencies only. A software component can be deployed independently and is subject to composition by third parties. Szyperski Postacademische Cursus Informatie Technologie vrije Universiteit amsterdam The technology matrix distribution mobility language platform reflection COM * +/DCOM + * +/+/CORBA + * * +/Java/Beans classes Java * + Java/RMI + classes Java * + Voyager + objects Java * + Postacademische Cursus Informatie Technologie vrije Universiteit amsterdam Components: Myths and Reality component-ware allows for combining components if semantical issues can be resolved component-ware simplifies software distribution and maintenance development becomes more complex component-ware support mega applications it affects performance significantly component-ware is a revolution wrong, it is an evolution from OO and C/S Postacademische Cursus Informatie Technologie unknown source vrije Universiteit amsterdam Component Questions • How to describe the interaction between components? • How to manage variety and flexibility? • How to guarantee critical system-wide properties? Postacademische Cursus Informatie Technologie vrije Universiteit amsterdam