TcpSentryScenarioClient.java

package TcpExamples;

import static TcpExamples.TcpSentryScenarioHandlerThread.HALT_WHO_GOES_THERE;
import static TcpExamples.TcpSentryScenarioHandlerThread.HOLD_IT_RIGHT_THERE;
import static TcpExamples.TcpSentryScenarioHandlerThread.YOU_MAY_PASS;
import java.io.*;
import java.net.*;

/**
 * This client program establishes a socket connection to the {@link TcpSentryScenarioDispatchServer},
 * then checks how long it takes to read the single line it expects as a server response.
 * No fancy footwork here, it is pretty simple and similar to {@link TcpExample3Client}.
 * 
 * @see TcpSentryScenarioDispatchServer
 * @see TcpSentryScenarioHandlerThread
 * @see TcpExample4Client
 * @see TcpExample4DispatchServer
 * @see TcpExample4HandlerThread
 *
 * @see <a href="../../../src/TcpExamples/TcpSentryScenarioTerminalLog.txt" target="blank">TcpSentryScenarioTerminalLog.txt</a>
 * @see <a href="../../../src/TcpExamples/TcpExample4SequenceDiagram.png" target="blank">TcpExample4SequenceDiagram.png</a>
 * @see <a href="../../../src/TcpExamples/TcpExample4SequenceSketch.png" target="blank">TcpExample4SequenceSketch.png</a>
 * 
 * @author Don Brutzman
 * @author Don McGregor
 * @author MV3500 class
 */
public class TcpSentryScenarioClient
{
    static String prefix = "[" + TcpSentryScenarioClient.class.getName() + "] ";
    
    /** Default constructor */
    public TcpSentryScenarioClient()
    {
        // default constructor
    }
    static String DESTINATION_HOST = "localhost";
    static int    MAX_LOOP_COUNT   = 6;

    /**
     * Program invocation, execution starts here
     * @param args command-line arguments
     */
    public static void main(String[] args) {
        try {
            System.out.println(prefix + " start, loop " + MAX_LOOP_COUNT + " times");
            System.out.println("=======================================================");
            for (int loopCount = 1; loopCount <= MAX_LOOP_COUNT; loopCount++) // loop then exit
            {
                System.out.println(prefix + " creating new socket #" + loopCount + "...");

                // We request an IP to connect to ("localhost") and
                // port number at that IP (2317). This establishes
                // a connection to that IP in the form of the Socket
                // object; the server uses a ServerSocket to wait for
                // connections.

                // open a socket for each loop
		Socket socket = new Socket(DESTINATION_HOST, 2317);
                
////////////////////////////////////////////////////////////////////////////////////////////
// Assignment code
                String myName = new String();
                // input stream and output stream 
                InputStream    inputStream       = socket.getInputStream();
                Reader         inputStreamReader = new InputStreamReader(inputStream);
                BufferedReader bufferedReader    = new BufferedReader(inputStreamReader);

                OutputStream outputStream = socket.getOutputStream();
                PrintStream  printStream  = new PrintStream(outputStream);

                String serverMessage = bufferedReader.readLine(); // blocks
                System.out.println(prefix + ": message received from server='" + serverMessage + "'");
                
                String sentryResponse = bufferedReader.readLine();
                System.out.println ("Sentry: " + sentryResponse);
            
                if (sentryResponse.equals(HALT_WHO_GOES_THERE))
                {
                    // user provides name from console
                    myName = System.console().readLine();
                    printStream.println(myName); // send it back to dispatch server
//                  System.out.println ("[trace] console return: " + myName);

                    sentryResponse = bufferedReader.readLine();
                    System.out.println ("Sentry: " + sentryResponse);

                    if      (sentryResponse.equals(YOU_MAY_PASS))
                    {
                         System.out.println ("Thank you officer.");
                    }
                    else if (sentryResponse.equals(HOLD_IT_RIGHT_THERE))
                    {
                         System.out.println ("OK I am outta here!");
                    }
                    // handling unexpected cases is important
                    else System.out.println ("I'm not sure what that means...");
                }

                System.out.println("=======================================================");
                // To push this further, launch multiple copies of TcpSentryScenarioClient simultaneously
                
                if (myName.equalsIgnoreCase("quit") || myName.equalsIgnoreCase("exit"))
                {
                    printStream.flush();
                    socket.close();
                }
            }

////////////////////////////////////////////////////////////////////////////////////////////

            System.out.println(prefix + " complete");
            // main method now exits
        } catch (IOException e) {
            System.out.println("Problem with " + prefix + " networking:networking:"); // describe what is happening
            System.out.println("Error: " + e);
            // Provide more helpful information to user if exception occurs due to running twice at one time
            if (e instanceof java.net.BindException) {
                System.out.println("*** Be sure to stop any other running instances of programs using this port!");
            }
        }
    }
}