Kĩ thuật lập trình - Chapter 12: Physical architecture layer design

Chapter 12:Physical Architecture Layer DesignObjectivesUnderstand the different physical architecture components.Understand server-based, client-based, and client–server physical architectures.Be familiar with distributed objects computing.Be able to create a network model using a deployment diagram.Understand how operational, performance, security, cultural, and political requirements affect the design of the physical architecture layer.Be familiar with how to create a hardware and software specification.IntroductionMost modern systems span two or more networked computersThe physical architecture layer design specifiesHow the system will be distributed across the computers What hardware and software will be usedMost systems’ design is constrained by existing systems and networksELEMENTS OF THE PHYSICAL ARCHITECTURE LAYERArchitectural ComponentsSoftware componentsData storageData access logicApplication logicPresentation logicHardware componentsComputers (clients, servers)NetworksServer-Based ArchitecturesThe server performs all four application functionsThe client only needed a monitor, a keyboard, and a communications device (e.g. modem)Data StorageData Access LogicApplication LogicPresentation LogicClient-Based ArchitecturesAll logic resides on the client computerA separate computer may hold the dataSimple to develop, but difficult to maintainData StorageData Access LogicApplication LogicPresentation LogicClient-Server ArchitecturesBalance processing between client and serverPredominant architecture in modern systemsAmount of client processing variesThin clients do only presentation logicThick clients do presentation and applicationApplication LogicPresentation LogicData StorageData Access LogicClient-Server TiersClient server architectures can have two or more tiers depending on application logic partitioning2-tier: all application and data logic on one server3-tier: application logic on one server, data logic on another4-tier: application logic split among two servers, data logic on anotherSometimes called an n-tier architectureDistributed Objects ComputingNext generation of client-server computingThe client need not know which server to callMiddleware intercepts the client request and sends it to the appropriate serverThree competing approachesCORBAEnterprise Java Beans.NETSelecting a Physical ArchitectureCost of infrastructureCost of developmentEase of developmentInterface capabilitiesControl and securityScalabilityArchitecture CharacteristicsServer-BasedClient-BasedClient-ServerCost of infrastructureVery highMediumLowCost of developmentMediumLowHighEase of developmentLowHighLow-MediumInterface capabilitiesLowHighHighControl and SecurityHighLowMediumScalabilityLowMediumHighINFRASTRUCTURE DESIGNDeployment DiagramRepresent relationships between hardware components of an information systemElements of a deployment diagramNodes: a computational resourceArtifacts: a piece of the information system which will be installed on a nodeCommunication paths: a communication link such as a network connection or a USB cableSample Deployment DiagramNetwork ModelShows the major components of the information system and their geographic locations throughout the organizationPurposes of the network model: To convey the complexity of the systemTo show how the system’s software components will fit togetherSample Network ModelNONFUNCTIONAL REQUIREMENTSNonfunctional Requirement TypesOperationalPerformanceSecurityCultural and PoliticalOperational RequirementsPerformance RequirementsSecurity RequirementsCultural & Political RequirementsSummaryElements of the Physical Architecture LayerInfrastructure DesignNonfunctional Requirements