ISM 50 - Business Information SystemsLectures 14Instructor: John MusacchioUC Santa CruzNov 9, 2010Class announcementsFor Next ClassRead: MySQL Database Case Database tutorialsMore on layeringSlides modified from those byDavid G. MesserschmittExample 1BobAliceBob sends a letter to AliceUS Postal ServiceUK Royal MailABC AirlinesEnvelopeShipping ContainerShipping ContainerEnvelopeLayer above is a client of thelayer belowLayer below as as a serverto the layer above.by utilizing the services of the layer below and adding capabilityEach layer provides services to the layer above.Interaction of layersThree types of softwareApplicationInfrastructure:Basic services (communication, storage, concurrency, presentation, etc.)Components and frameworks:What is in common among applicationsNetworkOperating systemMiddlewareApplication frameworks and componentsApplicationsMajor layersData and informationApplicationDeals with informationInfrastructureDeals with dataAssumes structure and interpretationIgnores structure and interpretationWeb browserFile systemOperatingsystemFileNetworkMessageCollection of packetsFragmentation AssemblyMessageHTMLScreenApplicationWeb serverExample 2Web pagePackage = file or messageInfrastructure deals with a package of data (non-standard terminology)collection of bitsspecified number and orderingInfrastructure stores and communicates packages while maintaining data integrity File for storage message for communicationData integrityRetain thevaluesordernumberof bits in a packageExample 3HHCHHC ServerHHC Server Application HHC Client ApplicationPassenger InformationWindows OSmessageNetworking Infrastructure(Contains: TCP/IP, WiFi)Collection of PacketsNetworking Infrastructure(Contains: TCP/IP, WiFi)Palm OSmessageExample 3: Network Infrastructure ExpandedHHC Server Application HHC Client ApplicationPassenger InformationWindows OSmessageTCP transport layerPalm OSmessageWiFi Link LayerPacketsWiFi Physical LayerNetworking InfrastructureTCP transport layerWiFi Link LayerPacketsWiFi Physical LayerNetworking InfrastructureRadio SignalsExample 4HHC ServerHHC Server Application DBMSWindows OSmessageNetworking InfrastructureLayers within TCP/IP, WiFiCollection of PacketsNetworking InfrastructureLayers within: TCP/IP, WiFiUnix OSmessageAirline DataserverHEADQUARTERSSend me todaysflight informationData and information in layersThe infrastructure should deal with data,or at most minimal structure and interpretation The application adds additional structure and interpretationThis yields a separation of concernsInformation in the infrastructureSometimes it is appropriate for the infrastructure to assume structure and interpretation for datato add capabilities widely useful to applicationsto help applications deal with heterogeneous platforms, where representations differAt most, data typesData and informationApplicationDeals with informationInfrastructureDeals with data typesAssumes structure and interpretationAssumes standard data
View Full Document
Unlocking...