举两个网际网路的应用例子

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1、WEEKLYQUIZ3(A)ComputerNetworks11.舉兩個網際網路的應用例子，說明其應用架構具有P2P及主從式架構﹖2Skype:centralizedserver:findingaddressofremoteparty:client-clientconnection:direct(notthroughserver)Instantmessage:centralizedservice:clientpresencedetection/locationuserregistersitsIPaddresswithc

2、entralserverwhenitcomesonlineusercontactscentralservertofindIPaddressesofbuddies32.Explaination(1)API(2)Socket(3)RTT(4)Proprietaryprotocol4APIApplicationprogramminginterfacethemethodbywhichanapplicationprogramrequestservicesfromlibrariesand/oroperatingsystems

3、ex.JavaAPI,iPhoneAPI5Socket網路上資料進出的地方位於應用層和傳輸層的介面6RTTRoundtriptime封包從發送開始到收到回應的時間7ProprietaryprotocolcommunicationsprotocolownedbyasingleorganizationorindividualExample:Skypeprotocol83.何謂Process？如何決定一個網路上的Process？9Process:programinexecutionAddressingprocesses:IP

4、andportnumberExamples:HTTPport80,FTPport21104.Flowcontrol與Congestioncontrol有何不同﹖11Flowcontrol調整sender端傳送資料的速率和receiver端處理速度相符，避免receiver端bufferoverflowCongestioncontrol控制sender端傳送資料的速率，避免網路中的上bufferoverflow(packetloss)125.舉例說明Non-persistentHTTP與PersistentHTTP的不同

5、﹖13假設一台伺服器上包含一份html檔和10份圖檔，共11個object：NonpersistentPersistent一次建立一條TCP連線，共建立11條只建立一次TCP連線消耗頻寬資源分為pipeline與withoutpipeline的方法有閒置狀態產生14ProblemsandQuestions151.Foracommunicationsessionbetweenapairofprocess,whichprocessistheclientandwhichistheserver?16Clientprocess:

6、processthatinitiatescommunicationServerprocess:processthatwaitstobecontacted172.Whatinformationisusedbyaprocessrunningononehosttoidentifyaprocessrunningonanotherhost?18TheIPaddressofthedestinationhostandtheportnumberofthedestinationsocket.193.Supposeyouwanttodoa

7、transactionfromremoteclienttoaserverasfastaspossible.WouldyouuseUDPorTCP?Why?20YouwoulduseUDP.WithUDP,thetransactioncanbecompletedinoneroundtriptime(RTT)-theclientsendsthetransactionrequestintoaUDPsocket,andtheserversendsthereplybacktotheclient'sUDPsocket.WithTC

8、P,aminimumoftwoRTTsareneeded-onetoset-uptheTCPconnection,andanotherfortheclienttosendtherequest,andfortheservertosendbackthereply.214.SupposetheHTMLfilereferences3ver