org.rifidi.emulator.io.comm.ip.udp.UDPOnCommunicationPowerState.java Source code

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Here is the source code for org.rifidi.emulator.io.comm.ip.udp.UDPOnCommunicationPowerState.java

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/*
 *  UDPOnCommunicationPowerState.java
 *
 *  Project:      RiFidi Emulator - A Software Simulation Tool for RFID Devices
 *  http://www.rifidi.org
 *  http://rifidi.sourceforge.net
 *  Copyright:       Pramari LLC and the Rifidi Project
 *  License:      Lesser GNU Public License (LGPL)
 *  http://www.opensource.org/licenses/lgpl-license.html
 */
package org.rifidi.emulator.io.comm.ip.udp;

import java.net.DatagramSocket;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.rifidi.emulator.common.PowerControllable;
import org.rifidi.emulator.io.comm.buffered.BufferedOnCommunicationPowerState;

/**
 * @author Matthew Dean
 *
 */
public class UDPOnCommunicationPowerState extends BufferedOnCommunicationPowerState {
    /**
     * The log4j logger for this class.
     */
    private static Log logger = LogFactory.getLog(UDPOnCommunicationPowerState.class);

    /**
     * The singleton instance for this state.
     */
    private static final UDPOnCommunicationPowerState SINGLETON_INSTANCE = new UDPOnCommunicationPowerState();

    /**
     * A default-access method for getting the singleton instance of this state
     * class. The default access is designed so that only other members of the
     * UDP package may use this class.
     * 
     * @return The singleton instance of this state class.
     */
    static UDPOnCommunicationPowerState getInstance() {
        return UDPOnCommunicationPowerState.SINGLETON_INSTANCE;
    }

    /**
     * A private constructor used for making the singleton instance of this
     * class.
     */
    private UDPOnCommunicationPowerState() {
        /* Do nothing special, no class variables are being used. */
    }

    /**
     * Suspends the server. <br>
     * 
     * Currently does nothing to the actual server socket (that is, connections
     * will still be accepted), but the underlying BufferedCommunication state
     * takes care of suspending the flow of information.
     * 
     * @see org.rifidi.emulator.io.comm.buffered.BufferedOnCommunicationPowerState#suspend(org.rifidi.emulator.common.PowerControllable)
     */
    @Override
    public void suspend(PowerControllable pcObject) {
        logger.debug("Suspend...");

        /* Invoke buffered handlers. */
        super.suspend(pcObject);

        /* Cast the passed PowerControllable to a TCPServerCommmunication. */
        UDPCommunication curUDPComm = (UDPCommunication) pcObject;

        /* Change to suspended state */
        curUDPComm.changePowerState(UDPSuspendedCommunicationPowerState.getInstance());
    }

    /**
     * Turns off the UDP communication object.
     * 
     * @see org.rifidi.emulator.io.comm.buffered.BufferedOnCommunicationPowerState#turnOff(org.rifidi.emulator.common.PowerControllable)
     */
    @Override
    public void turnOff(PowerControllable pcObject) {

        /* Invoke buffered handlers. */
        super.turnOff(pcObject);

        /* Cast the passed PowerControllable to a TCPServerCommmunication. */
        UDPCommunication curUDPComm = (UDPCommunication) pcObject;

        /* Disconnect and close the underlying socket */
        this.disconnect(curUDPComm);

        /* Change to the off state */
        curUDPComm.changePowerState(UDPOffCommunicationPowerState.getInstance());
    }

    /**
     * Disconnects the socket. Doing this will also kill any threads that are
     * running that are using this socket. In UDP sockets close is tightly bound
     * to a disconnect and thus the socket is also closed as well.
     */
    public void disconnect(UDPCommunication dconnudpComm) {

        DatagramSocket dgs = dconnudpComm.getDatagramSocket();
        boolean outputTest = dconnudpComm.isOutputOnly();

        if (outputTest) {
            /* If it is output only then the disconnect works fine */
            dgs.disconnect();
        } else {
            /* TODO Need to resolve bug in UDPCommunication where
             * the disconnect hangs when there is both an incoming
             * and outgoing message handler
             */
            logger.warn("UDPCommunication was closed but not disconnected"
                    + " due to UDPIncoming Handler Bug - results may vary");
        }

        /* close the datagram socket */
        dgs.close();
    }

}