Introduction

The project consists of two interacting application programs, a server and a client:

• The server creates a socket in the Internet domain bound to port SERVER_PORT (a constant that is passed as a argument), accepts connections from clients, and responds to queries from each client. For this project, a query is an arbitrary string and the response is the string prefixed by a RESPONSE_PREFIX (also a constant that is passed as a argument).

• The client creates a TCP connection to the server, reads a query (string line) from standard input, sends the query to the server,  waits for the response, and then repeats this with the next query. It exits if the query is the sring "Bye".

• The class Server (in file Server.java) creates the server socket, listens on the server port, accepts a client connection, launches a thread called ServerThread, and goes back to listening on the server port. ServerThread handles messages from the accepted client; i.e., receives queries, sends responses, and exits upon receiving the query "Bye",

• The class Client (in file Client.java) launches a thread called ClientThread, reads queries (strings) from standard input, passes them to ClientThread, and exits upon encountering query "Bye". ClientThread handles the communication with the server; i.e., send query to server and receive response from server.

Assignment

• The class ServerThread
• Extends Thread
• Has a constructor  ServerThread(Socket cSock, String respPrefix), where cSock is the socket for talking to client and respPrefix is the RESPONSE_PREFIX. This constructor is called by Server.
• Has a method public void run(), which is its runnable method.
• Source is supplied in file ServerThread.java.

• The class ClientThread
• Extends Thread
• Has a constructor ClientThread(String[] args), where the first element of args indicates the server host name and the second element of args indicates the server port number. This constructor is called by Client.
• Has a method public void sendPacket(String buf), where buf is the query to be sent to the server. This method is called by Client.
• The runnable method public void run().

The command line syntax for the Server and Client is given below. The server program takes two command-line arguments: the response_prefix and the server port. The client program also takes two command-line arguments: the name of the host where your server is running and the port number of this host.

java Server <RESPONSE_PREFIX> <server_port>
java Client <server_hostname>  <port>

Server Socket         http://www.javasoft.com/products/jdk/1.1/docs/api/java.net.ServerSocket.html
Socket                   http://www.javasoft.com/products/jdk/1.1/docs/api/java.net.Server.html
Thread                  http://www.javasoft.com/products/jdk/1.1/docs/api/java.lang.Thread.html
String                    http://www.javasoft.com/products/jdk/1.1/docs/api/java.lang.String.html
InetAddress          http://www.javasoft.com/products/jdk/1.1/docs/api/java.net.InetAddress.html
BufferedReader       http://www.javasoft.com/products/jdk/1.1/docs/api/java.io.BufferedReader.html
PrintWriter           http://www.javasoft.com/products/jdk/1.1/docs/api/java.io.PrintWriter.html

Custom Networking         http://java.sun.com/docs/books/tutorial/networking/index.html

Use netstat(1) to see what sockets have been created by your programs (you may have put them in the background; once a program terminates, the sockets it created go away).