課件第13章應(yīng)用層簡介

1、 1Chapter 13 Application LayerClient-server paradigmPeer-to-peer paradigmSummary13.1 Client-Server ParadigmClient（客戶）A program running on the local machine requesting service from a serverFiniteActive open and active closeServer（服務(wù)器）A program running on the remote machine providing service to the cl

2、ientsInfinitePassive open 2 3Concurrency，并發(fā)ClientIteratively（順序）: running one by oneConcurrently: running at the same timeServerConnectionless iterative：UDPConnectionless concurrentConnection-oriented iterativeConnection-oriented concurrent：TCP、SCTPConnectionless Iterative Server 4Connection-Oriente

3、d Concurrent Server 5Socket Interface，套接字接口Interface，接口A set of instructions designed for interaction between two entitiesSocket interface 6Physical layerData link layerNetwork layerTransport layerSocket interfaceApplication layer操作系統(tǒng)應(yīng)用程序SocketIn the Internet：a software data structureSOCK_STREAM：用于

4、TCPSOCK_DGRAM：用于UDPSOCK_SEQPACKET：用于SCTPSOCK_RAW：用于直接使用IP服務(wù)的應(yīng)用Socket addressstruct sockaddr_in unsigned short sin_family;unsigned short sin_port;unsigned long sin_addr;char sin_zero8;Socket functionssocket, bindconnect, listen, accept, forksend, recvsendto, recvfromclose 7相關(guān)課程：網(wǎng)絡(luò)軟件設(shè)計13.2 Peer-to-Pee

5、r ParadigmTwo peer computers can communicate with each other to exchange servicesThe P2P paradigm does not ignore the C/S paradigmLet the duty of a server be shared by some users that want to participate in the processA computer can be a client for a specific application at one moment and the server at another moment 8 913.3 S