generic connection framework

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1、Chapter13GenericConnectionFramework575P:10CompCompRef8710-9ch13.vpThursday,February06,20031:28:02PM576J2ME:TheCompleteReferencehepartnershipbetweenJ2MEandsmallcomputingdevicesopensthepossibilityofdevelopingalargedistributivesystemthatcombinestheco

2、nvenienceofTportablecomputingwiththehorsepowerofaback-endprocessingsystem.Asmallcomputingdeviceiscompactandhassufficientresourcestocollectanddisplayinformationsuchasanorderform,butlacksthecapabilitytofullyprocessandstorethisinformation.Incontrast,aback

3、-endprocessingsystemhasthepowerandstoragetohandleanydataprocessingrequirement,butlackstheconvenientsizeandflexibilitytoworkunderanyconditions,whicharethehallmarksofasmallcomputingdevice.J2MEenablesyoutobuildanapplicationthatovercomesthedisadvantagesofb

4、othbyexchangingdatabetweenasmallcomputingdeviceandaback-endprocessingsystem.Youcandesignanapplicationtoutilizeasmallcomputingdevice’scapabilityofdatacaptureanddatadisplayandaback-endsystem’scapabilityforprocessingandstoringthedata.Theexchangeoccursinre

5、altimeoveraconnectioncreatedbyaJ2MEapplicationbetweenthesmallcomputingdeviceandtheremotecomputer.ThisconnectioniscreatedusingtheGenericConnectionFramework(GCF),whichyou’lllearnaboutinthischapter.TheConnectionAconnectionisapathbetweentwocomputingdevices

6、thatutilizesahard-wired(cable)technologyorwirelesstechnologytotransmitandreceivedataoveranetwork.Thesedevicescanbeasmallcomputingdeviceandaback-endprocessingsystemortwosmallcomputingdevices.Threepiecesofinformationarerequiredtoestablishaconnectionbetwe

7、entwocomputingdevices.Theseareanetworkaddress,communicationsprotocol,andcommunicationparameters.(Parametersarenotnecessarilyrequireddependingontherequirementsoftheremotecomputingdevice.)Thenetworkaddressuniquelyidentifieseachcomputingdeviceonanetwork.A

8、nInternetprotocol(IP)addressisusedonmanynetworks,althoughotheraddressingschemesexist.Acommunicationsprotocolisasetofrulesthatdescribehowdataistransmittedbetweentwocomputingdevices.Bothcomputingdevicesmustagreeonacommunicationsprotocolbe