南开软院2012网络课程课件.ppt

Client/server socket interaction: TCP wait for incoming connection request connectionSocket = welcomeSocket.accept() create socket, port=x, for incoming request: welcomeSocket = ServerSocket() create socket, connect to hostid, port=x clientSocket = Socket() close connectionSocket read reply from clientSocket close clientSocket Server (running on hostid) Client send request using clientSocket read request from connectionSocket write reply to connectionSocket TCP connection setup Application 2-* Client process client TCP socket Stream jargon stream is a sequence of characters that flow into or out of a process. input stream is attached to some input source for the process, e.g., keyboard or socket. output stream is attached to an output source, e.g., monitor or socket. Application 2-* Socket programming with TCP Example client-server app: 1) client reads line from standard input (inFromUser stream) , sends to server via socket (outToServer stream) 2) server reads line from socket 3) server converts line to uppercase, sends back to client 4) client reads, prints modified line from socket (inFromServer stream) Application 2-* Example: Java client (TCP) import java.io.*; import .*; class TCPClient { public static void main(String argv[]) throws Exception { String sentence; String modifiedSentence; BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in)); Socket clientSocket = new Socket(hostname, 6789); DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream()); create input stream create clientSocket object of type Socket, connect to server create output stream attached to socket Application 2-* This package defines Socket() and ServerSocket() classes server port # server name, e.g., Example: Java client (TCP), cont. BufferedReader inFromServer = new BufferedReader(new InputStreamReader(c