Kĩ thuật lập trình - Chapter 16: Component based embedded systems

Chapter 16Component based embedded systemsPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsOverviewIntroductionComponent technology in embedded systemsCase study – ABB’s Field DevicesPrerequisites for effective development of Component-based embedded systemsSummaryPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsWhere is the problem?Huge market arises for embedded devices, and thus for software for themSimilar basic functionalities are repeatedNew functionalities are added constantlyShorter development time is requiredPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsIntroductionPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsEmbedded vs. Component-basedMonolithic approach requires re-implementing the functionalitiesComponent based SE provides a mean to reuse the functionalitiesComponent based SE can provide a framework instead of technologyEmbedded devices are too small for component off-the-shelf technologiesPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsComponent technology in embedded worldContractually specified interfacesComponent as a unit of composition and independent deploymentExplicit context dependenciesComponent granularityReuseLocation transparencyComponent wiringPortability, platform independencePage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsContractually specified interfacesState-of-the-art technologies approach:Interfaces as pure collection of methods. Embedded environment constraint:Non-functional specifications are equally important part of the contractPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsInterfaces IIComponent interfaces support:Late binding,Polymorphism,Semantic specificationPre conditions,Post conditions,Invariants Page Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsUnit of composition and independent deploymentRun-time compositionComponent model,Run-time environment,Dynamic communication,Design-time compositionCapable of generating monolithic firmware from component-based design,OptimizationPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsExplicit context dependenciesWhat is a context in embedded world?Other components and interfacesRun-time environmentCPU,RTOS,Component implementation language,Resource constraintsPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsComponent granularityCoarse-grained components,Too heavy bag of unnecessary functionality,Too much resources used,Fine-grained components,Light, unneeded functionality reduced,Scarcer uses of resources,Greater communication overhead,Page Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsReuse Black-box reuseFrom component’s user point of view,White-box reuseFrom composition environment point of viewGray-box reuse (composition environment)If clear conventions for knowledge about implementation are introducedPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsArchitecture and frameworksDefining components alone will not lead to reuseCommon architecture for family of embedded devicesFramework for developmentPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsPortability, Platform independenceSource level portability suffices,Design-time composition,Run-time environment restrictionsSource level portability requires:Agreement on implementation language,Agreement on available libraries,Providing proper abstractions (i.e. RTOS API)Page Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsOther issuesLocation transparencyFor embedded devices there is a single location,Component wiringNeeded for flexible composition of software,Optimizes component interaction,Component ”glue code” should be in implementation languagePage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsCase study – ABB’s Field devicesSynchronous approachArchitecture of the field devicesDynamic behaviorInter-component communicationPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsSynchronous approachSynchronous languages have been developed to simplify the programming of reactive systemsProvide the mean to handle concurrency, determinism, response time controlBased on synchrony hypothesisPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsArchitecture of the field devicePage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsDynamic behaviorspeedTv,Tv,kpSetpointerroroutsetpointa)Controller(2)manipulatedvariable(3)ControlledSystem actual value (1)b)SignalbusSensors(1) PID (2)Actuator(3)outspeedPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsInter-component communicationBased on Signal BusSignal Bus communication is maintained by Object ManagerCommunication itself is based on signalsOne source per signalPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsTypes of InterfacesUserInterfaceReal-timeSystemProcessInterfaceCommunicationLinkMass storageInterface(1)(2)(3)(4)Page Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsPrerequisites for effective developmentComponent modelAdditionally must address non functional properties,Allow for code generation,Allow for efficient functional interfaces,Allow for specification of architectural styles that describe component connections and containment relations,Page Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsFrameworkComponentRepositoryCompositionenvironmentRun-timeenvironmentComponentModelComponent-basedArchitecture forfield devicesPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsPrerequisites IIComponent-based architecture for field devicesFramework,Compile time optimizations,Field-bus architecture,RepositoryStorage and retrieval of components,Storage of non-functional properties, implementation, support and test scripts,Versioning Page Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsPrerequisites IIIComposition environmentConstraint verification,Component adaptation and code generation,Composition techniques,Definition of composition rulesPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsPrerequisites IVRun-time environmentProvide efficient implementation model,Address embedded systems constraints,Allow for compilation to optimized firmware thus allowing for no extra run-time environment that RTOSAllow for hardware and RTOS independent implementation of componentsPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsCase study summaryArchitecture of the field devicePrerequisites for effective developmentFrameworkPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systemsPresentation summaryIntroductionComponent technology in embedded systemsCase study – ABB’s Field DevicesPrerequisites for effective development of Component-based embedded systemsSummaryPage Building Reliable Component-based Systems Chapter 16 - Component based embedded systems