modbusudplistener.java

jamod is an object oriented implementation of the Modbus protocol, realized 100 in Java. It allows

//License
/***
 * Java Modbus Library (jamod)
 * Copyright (c) 2002-2004, jamod development team
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the author nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS ``AS
 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 ***/
package net.wimpi.modbus.net;

import java.net.InetAddress;

import net.wimpi.modbus.Modbus;
import net.wimpi.modbus.ModbusCoupler;
import net.wimpi.modbus.ModbusIOException;
import net.wimpi.modbus.io.ModbusUDPTransport;
import net.wimpi.modbus.msg.ModbusRequest;
import net.wimpi.modbus.msg.ModbusResponse;

/**
 * Class that implements a ModbusUDPListener.<br>
 *
 * @author Dieter Wimberger
 * @version 1.2rc1 (09/11/2004)
 */
public class ModbusUDPListener {

  private UDPSlaveTerminal m_Terminal;
  private ModbusUDPHandler m_Handler;
  private Thread m_HandlerThread;
  private int m_Port = Modbus.DEFAULT_PORT;
  private boolean m_Listening;
  private InetAddress m_Interface;

  /**
   * Constructs a new ModbusUDPListener instance.
   */
  public ModbusUDPListener() {
  }//ModbusUDPListener

  /**
   * Create a new <tt>ModbusUDPListener</tt> instance
   * listening to the given interface address.
   *
   * @param ifc an <tt>InetAddress</tt> instance.
   */
  public ModbusUDPListener(InetAddress ifc) {
    m_Interface = ifc;
  }//ModbusUDPListener

  /**
   * Returns the number of the port this <tt>ModbusUDPListener</tt>
   * is listening to.
   *
   * @return the number of the IP port as <tt>int</tt>.
   */
  public int getPort() {
    return m_Port;
  }//getPort

  /**
   * Sets the number of the port this <tt>ModbusUDPListener</tt>
   * is listening to.
   *
   * @param port the number of the IP port as <tt>int</tt>.
   */
  public void setPort(int port) {
    m_Port = ((port>0)? port : Modbus.DEFAULT_PORT);
  }//setPort

  /**
   * Starts this <tt>ModbusUDPListener</tt>.
   */
  public void start() {
    //start listening
    try {
      if(m_Interface == null) {
        m_Terminal = new UDPSlaveTerminal(InetAddress.getLocalHost());
      } else {
        m_Terminal = new UDPSlaveTerminal(m_Interface);
      }
      m_Terminal.setLocalPort(m_Port);
      m_Terminal.activate();

      m_Handler = new ModbusUDPHandler(m_Terminal.getModbusTransport());
      m_HandlerThread = new Thread(m_Handler);
      m_HandlerThread.start();

    } catch (Exception e) {
      //FIXME: this is a major failure, how do we handle this
    }
    m_Listening = true;
  }//start

  /**
   * Stops this <tt>ModbusUDPListener</tt>.
   */
  public void stop() {
    //stop listening
    m_Terminal.deactivate();
    m_Handler.stop();
    m_Listening = false;
  }//stop

  /**
   * Tests if this <tt>ModbusTCPListener</tt> is listening
   * and accepting incoming connections.
   *
   * @return true if listening (and accepting incoming connections),
   *          false otherwise.
   */
  public boolean isListening() {
    return m_Listening;
  }//isListening

  class ModbusUDPHandler
      implements Runnable {

    private ModbusUDPTransport m_Transport;
    private boolean m_Continue = true;

    public ModbusUDPHandler(ModbusUDPTransport transport) {
      m_Transport = transport;
    }//constructor

    public void run() {
      try {
        do {
          //1. read the request
          ModbusRequest request = m_Transport.readRequest();
          //System.out.println("Request:" + request.getHexMessage());
          ModbusResponse response = null;

          //test if Process image exists
          if (ModbusCoupler.getReference().getProcessImage() == null) {
            response =
                request.createExceptionResponse(Modbus.ILLEGAL_FUNCTION_EXCEPTION);
          } else {
            response = request.createResponse();
          }
          /*DEBUG*/
          if (Modbus.debug) System.out.println("Request:" + request.getHexMessage());
          if (Modbus.debug) System.out.println("Response:" + response.getHexMessage());

          //System.out.println("Response:" + response.getHexMessage());
          m_Transport.writeMessage(response);
        } while (m_Continue);
      } catch (ModbusIOException ex) {
        if (!ex.isEOF()) {
          //other troubles, output for debug
          ex.printStackTrace();
        }
      } finally {
        try {
          m_Terminal.deactivate();
        } catch (Exception ex) {
          //ignore
        }
      }
    }//run

    public void stop() {
      m_Continue = false;
    }//stop

  }//inner class ModbusUDPHandler

}//class ModbusUDPListener