Client/Server networking

[mike hengst]

I am not sure this is the right forum to ask my question but here goes. I am trying to write this application that calls for a client and a server along with other classes which I have not got to yet. Here is the problem: The client won't accept input. I had it working at one point but had to fix a bug and now it does not accept user input. If someone could just take a look at my code and tell me where my error is I would appreciate it greatly. Here are the client and server classes:

package java146.project2;
import java.net.*;
import java.io.*;
/**
 *  Description of the Class
 *
 */
public class Client extends java.lang.Object {
    /**
     *  Description of the Method
     *
     *@param  args             Description of the Parameter
     *@exception  IOException  Description of the Exception
     */
    public static void main(String args[]) throws IOException {
        System.out.println("in main of client");
        Client  c  = new Client();
        c.runClient();
    }

    /**
     *  Description of the Method
     *
     *@exception  IOException  Description of the Exception
     */
    private void runClient() throws IOException {
        System.out.println("inside runClient from Client");
        Socket          sock        = null;
        PrintWriter     out         = null;
        BufferedReader  in          = null;
        BufferedReader  cmdLine     = null;
        String          host        = "localhost";
        try {
            //creating new socket and input and output streams
            sock = new Socket(host, 4444);
            out = new PrintWriter(sock.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(sock.getInputStream()));
            cmdLine = new BufferedReader(new InputStreamReader(System.in));
        }
        //catching error if there is no host or unable to connect
        catch(UnknownHostException uhe) {
            return;
        }
        catch(IOException ioe) {
            //call errorlogger here? stacktrace?
            return;
        }
        String          fromServer  = "";
        String          fromUser    = "";
        //while loop to run through input
        String          str         = "";
        boolean         more        = true;
        System.out.println("in client before while loops");
        while(true) {
            while(more) {
                //System.out.println("in client inside while loops");
        //System.out.println(fromServer);
                fromServer = in.readLine();
                if(fromServer.equalsIgnoreCase("bye")) {
                    more = false;
                    break;
                }
                if(fromServer.equalsIgnoreCase("~Done")) {
                    break;
                }
                //System.out.println("inside while printing of fromServer");
                System.out.println(fromServer);
            }
            if(!more) {
                break;
            }
            System.out.println("reading from client");
            fromUser = cmdLine.readLine();
            out.println(fromUser);
        }
        System.out.println("in client after while loops");
        out.close();
        in.close();
        cmdLine.close();
        sock.close();
    }
}
// -- end class Client
  

 package java146.project2;
import java.net.*;
import java.io.*;
import java146.util.*;
/**
 *  Description of the Class
 *
 */
public class Server {
             String           file  = "";
             String           dir   = "";
    private  ErrorLogger      el;
    private  PropertyHandler  ph;

    /**
     *  This class instantiates itself
     *
     *@param  args             The command line arguments
     *@exception  IOException  Description of the Exception
     */
    public static void main(String[] args) throws IOException {
        Server  pts  = new Server();
        System.out.println("server has started");
        pts.runIt();
    }

    /**
     *  This methos creates an instance of propertyhandler, errorlogger
     *
     *@exception  IOException  Description of the Exception
     */
    public void runIt() throws IOException {
        ServerSocket  serverSocket  = null;
        boolean       listening     = true;
        Search        search        = new Search(file, dir);
        try {
            ph = new PropertyHandler("/config/project2.properties");
            el = new ErrorLogger(ph);
            //file = ph.getNamedProperty("emplocation");
            System.out.println(file);
        }
        catch(Error e) {
            System.out.println("Error in run()");
            e.printStackTrace();
            return;
        }
        try {
            serverSocket = new ServerSocket(4444);
            System.err.println("Starting server... ");
        }
        catch(IOException ioe) {
            System.out.println("Could not listen on port: 4444.");
            el.logError(ioe);
            return;
        }
        while(listening) {
            //new thread object with errorlogger and prophandler passed to it
            //have to make thread safe the errorlogger-file possibly written to it
            //at the same time
            System.out.println("waiting");
            new EmpThread(serverSocket.accept(), el, ph, search).start();
            System.out.println("new thread started");

        }
        serverSocket.close();
    }
}
// -- end class ProjectTwoServer
 

 
package java146.project2;
import java.net.*;
import java.io.*;
import java146.util.*;
/**
 */
public class EmpThread extends Thread {
    private Socket socket = null;
    private PropertyHandler ph = null;
    private ErrorLogger el = null;
    private Search s = null;

    /**
     *  Constructor for the EmpThread object
     *
     *@param  socket  Description of Parameter
     *@param  el      Description of the Parameter
     *@param  ph      Description of the Parameter
     *@param  s       Description of the Parameter
     */
    public EmpThread(Socket socket, ErrorLogger el, PropertyHandler ph, Search s) {
        super("EmpThread");
        this.socket = socket;
        this.ph = ph;
        this.el = el;
        this.s = s;
        System.out.println("in EmpThread constructor");
    }

    /**
     *  Main processing method for the Project2Thread object
     */
    public void run() {
        try {
            System.out.println("Start of thread");
            //out goes to client in, in comes from  client out
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String inLine = null;
            String outLine = "";
            
            //instance of project2protocol
            Protocol p = new Protocol();
            
            outLine = p.processInput(inLine);
            
           //System.out.println("outLine: " + outLine);
            
            out.println(outLine);
            
            System.out.println("Outside while that calls processInput()");
            while ((inLine = in.readLine()) != null) {
                
                System.out.println("Inside while that calls processInput()");
                
                outLine = p.processInput(inLine);
                //see what is being output
                out.println(outLine + " inside");
                
                if (outLine.equalsIgnoreCase("Bye")) {
                    break;
                }
            }
            out.close();
            in.close();
            socket.close();
            //do we print trace or send to errorlogger?
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }
}
// -- end class Thread
 

[William Barnes]

My favorite part of the code:

/**
*  Description of the Class
*
*/

[William Barnes]

The client won't accept input.

If this is the problem I don't understand why you are posting more than just the Client class.
You have all sorts of debugging print statements in the code already, so you should be able to give us a better clue as to where the problem is.

System.out.println("reading from client");
fromUser = cmdLine.readLine();
out.println(fromUser);

Is it possible that you are just missing a "System" in front of the last line here?

[mike hengst]

I posted my server and thread classes so you could see where I was sending the input from the client. out is my printwriter and outputs to the server the user input. The problem is once the client displays a menu it is supposed to accept user inputs such as 1 or 2 or 3 etc and sends that to the server to retrieve a file etc... Instead the cursor just sits there.???

[Stan James]

Your client is connecting and then reading somethign from the server. Any chance the server is not sending anything?
here's a little socket project of my own:
http://www.surfscranton.com/architecture/CmdServer.htm
I'm new at sockets, and haven't implemented shutdown commands, so it's not perfect. I posted it on my site to solicit any and all constructive comments.
The client spawns a separate thread to read responses from the server, allowing the server to send zero to many responses to any request. The client will never get "hung" waiting for something from the server.

package com.saxman.cmdserver;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.Socket;
/**
 * Interactive client for execution of commands on another machine running SocketServer.
 * A command entered at the prompt for this program is forwarded to the remote server.
 * While executing a remote command, this program displays any prompts or messages
 * issued by the command, and forwards any user input to the command. Enter an empty
 * line to terminate the client.
 * <p>
 * Command line arguments are [server] and [port]
 */
public class CmdClient
{
   String mServer = "uninitialized";
   String mPort   = "uninitialized";
   PrintWriter    mWriter;
   Socket         mSocket;
   public CmdClient()
   {
   }
   /**
    * Command line arguments are [server] and [port]
    */
   public static void main( String[] args )
   {
      new CmdClient( ).execute( args );
   }
   private void execute( String[] args )
   {
      try
      {
         configure( args );
         connect();
         sendCommands();
         mSocket.close();
      }
      catch( Exception e )
      {
         System.out.println("CmdClient.main: Exception " + e);
      }
   }
   private void configure( String[] args )
   {
      if ( args.length > 0 ) mServer = args[0];
      if ( args.length > 1 ) mPort   = args[1];
      System.out.println("CmdClient.configure Server=" + mServer + ":" + mPort );
   }
   private void connect()
   throws IOException
   {
      mSocket = new Socket( mServer, Integer.parseInt( mPort ) );
      mWriter = new PrintWriter( mSocket.getOutputStream(), true );
      new StreamReader( mSocket.getInputStream(), "SocketServerResponse" ).start();
      System.out.println("CmdClient.connect Successful");
   }
   private void sendCommands()
   throws IOException
   {
      BufferedReader lStdIn  = new BufferedReader( new InputStreamReader( System.in ) );
      String lLine = "";
      while ( !( lLine = lStdIn.readLine() ).equals( "" ) )
      {
         System.out.println("CmdClient>");
         mWriter.println( lLine );
         mWriter.flush();
      }
   }
}
  

[Stan James]

Forgot the StreamReader.

package com.saxman.cmdserver;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.IOException;
/**
 * Reads a line at a time from an input stream on its own thread. This can be used
 * to handle asynchronous input. For example, you might send a command to a socket
 * server that sends back several progress reports over the next few minutes.
 * <p>
 * The thread stops when the input line is null or equals the HaltCondition.
 * <p>
 * Override processLine to do something with the incoming data. Override processError
 * to do something useful on error.
 */
public class StreamReader extends Thread
{
   protected BufferedReader mReader;
   protected String mName;
   protected String mHaltCondition = null;
   /**
    * Constructor.
    * @param InputStream aStream - what we read
    * @param String aName - an identifier used in messages
    */
   StreamReader( InputStream aStream, String aName )
   {
      mReader = new BufferedReader( new InputStreamReader(aStream) );
      mName   = aName;
   }
   public void run()
   {
      try
      {
         String lLine = null;
         while ( ( lLine = mReader.readLine() ) != null )
         {
            if ( null != mHaltCondition )
               if ( lLine.equals( mHaltCondition ) )
                  break;
            processLine( lLine );
         }
      }
      catch (IOException e)
      {
         processError( e );
      }
   }
   /** Default implementation displays the line and continues. */
   protected void processLine( String aLine )
   throws IOException
   {
      System.out.println( mName + ": Line=" + aLine );
   }
   /** Default implementation displays the error and continues. */
   protected void processError( Exception e )
   {
      System.out.println( this.getClass().getName() + " " + mName + " Exception " + e );
   }
   public void   setHaltCondition( String aHaltCondition ) { mHaltCondition = aHaltCondition; }
   public String getHaltCondition() { return mHaltCondition; }
}
  

[William Barnes]

while(true) 
{
  while(more) 
  {
    //System.out.println("in client inside while loops");
    //System.out.println(fromServer);
    fromServer = in.readLine();
    if(fromServer.equalsIgnoreCase("bye")) 
    {
      more = false;
      break;
    }
    if(fromServer.equalsIgnoreCase("~Done")) 
    {
      break;
    }
   //System.out.println("inside while printing of fromServer");
   System.out.println(fromServer);
  }
  if(!more) 
  {
    break;
  }
}  

Am I missing something here? How do you ever get out of these loops?

[mike hengst]

Here is the code I have working:

 package java146.project2;
import java.net.*;
import java.io.*;
import java146.util.*;
/**
 *  Description of the Class
 *
 *@author     MHengst
 *@created    March 25, 2003
 */
public class Server {
             String           file  = "";
             String           dir   = "";
    private  ErrorLogger      el;
    private  PropertyHandler  ph;

    /**
     *  This class instantiates itself
     *
     *@param  args             The command line arguments
     *@exception  IOException  Description of the Exception
     */
    public static void main(String[] args) throws IOException {
        Server  pts  = new Server();
        System.out.println("server has started");
        pts.runIt();
    }

    /**
     *  This methos creates an instance of propertyhandler, errorlogger
     *
     *@exception  IOException  Description of the Exception
     */
    public void runIt() throws IOException {
        ServerSocket  serverSocket  = null;
        boolean       listening     = true;
        Search        search        = new Search(file, dir);
        try {
            ph = new PropertyHandler("/config/project2.properties");
            el = new ErrorLogger(ph);
            //file = ph.getNamedProperty("emplocation");
            System.out.println(file);
        }
        catch(Error e) {
            System.out.println("Error in run()");
            e.printStackTrace();
            return;
        }
        try {
            serverSocket = new ServerSocket(4444);
            System.err.println("Starting server... ");
        }
        catch(IOException ioe) {
            System.out.println("Could not listen on port: 4444.");
            el.logError(ioe);
            return;
        }
        while(listening) {
            //new thread object with errorlogger and prophandler passed to it
            //have to make thread safe the errorlogger-file possibly written to it
            //at the same time
            System.out.println("waiting");
            new EmpThread(serverSocket.accept(), el, ph, search).start();
            System.out.println("new thread started");

        }
        serverSocket.close();
    }
}
// -- end class ProjectTwoServer
 

package java146.project2;
import java.net.*;
import java.io.*;
import java146.util.*;
/**
 *@author     mhengst
 *@created    March 23, 2003
 */
public class EmpThread extends Thread {
    private Socket socket = null;
    private PropertyHandler ph = null;
    private ErrorLogger el = null;
    private Search s = null;

    /**
     *  Constructor for the Project2Thread object
     *
     *@param  socket  Description of Parameter
     *@param  el      Description of the Parameter
     *@param  ph      Description of the Parameter
     *@param  s       Description of the Parameter
     */
    public EmpThread(Socket socket, ErrorLogger el, PropertyHandler ph, Search s) {
        super("EmpThread");
        this.socket = socket;
        this.ph = ph;
        this.el = el;
        this.s = s;
        System.out.println("in EmpThread constructor");
    }

    /**
     *  Main processing method for the Project2Thread object
     */
    public void run() {
        try {
            System.out.println("Start of thread");
            //out goes to client in, in comes from  client out
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String inLine = null;
            String outLine = "";
            
            //instance of project2protocol
            Protocol p = new Protocol();
            
            outLine = p.processInput(inLine);
            
           //System.out.println("outLine: " + outLine);
            
            out.println(outLine);
            
            System.out.println("Outside while that calls processInput()");
            while ((inLine = in.readLine()) != null) {
                
                System.out.println("Inside while that calls processInput()");
                
                outLine = p.processInput(inLine);
                //see what is being output
                out.println(outLine + " this is what is being out.println inside");
                
                if (outLine.equalsIgnoreCase("Bye")) {
                    break;
                }
            }
            out.close();
            in.close();
            socket.close();
            //do we print trace or send to errorlogger?
        } catch (IOException ioe) {
            ioe.printStackTrace();
        }
    }
}
// -- end class Thread
  

package java146.project2;
import java.net.*;
import java.io.*;
/**
 *  Description of the Class
 *
 *@author     MHengst
 *@created    March 26, 2003
 */
public class Client extends java.lang.Object {
    /**
     *  Description of the Method
     *
     *@param  args             Description of the Parameter
     *@exception  IOException  Description of the Exception
     */
    public static void main(String args[]) throws IOException {
        System.out.println("in main of client");
        Client  c  = new Client();
        c.runClient();
    }

    /**
     *  Description of the Method
     *
     *@exception  IOException  Description of the Exception
     */
    private void runClient() throws IOException {
        System.out.println("inside runClient from Client");
        Socket          sock        = null;
        PrintWriter     out         = null;
        BufferedReader  in          = null;
        BufferedReader  cmdLine     = null;
        String          host        = "localhost";
        try {
            //creating new socket and input and output streams
            sock = new Socket(host, 4444);
            out = new PrintWriter(sock.getOutputStream(), true);
            in = new BufferedReader(new InputStreamReader(sock.getInputStream()));
            cmdLine = new BufferedReader(new InputStreamReader(System.in));
        }
        //catching error if there is no host or unable to connect
        catch(UnknownHostException uhe) {
            return;
        }
        catch(IOException ioe) {
            //call errorlogger here? stacktrace?
            return;
        }
        String          fromServer  = "";
        String          fromUser    = "";
        //while loop to run through input
        String          str         = "";
        boolean         more        = true;
        System.out.println("in client before while loops");
        while(true) {
            while(more) {
                //System.out.println("in client inside while loops");
                //System.out.println(fromServer);
                fromServer = in.readLine();
                if(fromServer.equalsIgnoreCase("bye")) {
                    more = false;
                    break;
                }
                //System.out.println(fromServer + " Before checking for ~Done");
            
            if(fromServer.equalsIgnoreCase("~Done")) {
                break;
            }
            //System.out.println(fromServer + " After checking for ~Done");
            //System.out.println("inside while printing of fromServer");
            System.out.println(fromServer);
            }
            if(!more) {
                break;
            }
            System.out.println("reading from client");
            fromUser = cmdLine.readLine();
            out.println(fromUser);
        }
        //fromUser = cmdLine.readLine();
        System.out.println("in client after while loops");
        out.close();
        in.close();
        cmdLine.close();
        sock.close();
    }
}
// -- end class Client