rdvgreeter.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/************************************************************************
 *
 * $Id: RdvGreeter.java,v 1.6 2004/05/18 19:21:55 bondolo Exp $
 *
 * Copyright (c) 2002 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is bansed on the BSD license adopted by the Apache Foundation.
 *********************************************************************************/

package net.jxta.impl.rendezvous;


import java.io.IOException;

import net.jxta.endpoint.EndpointListener;
import net.jxta.endpoint.Message;


/**
 * This abstract class must be extended by all rendezvous peer greeter.
 *
 * A Greeter is reponsible for receiving messages from walkers, and
 * push them to the service that is listening to them.
 *
 * @see net.jxta.impl.rendezvous.limited.LimitedRangeWalk
 * @see net.jxta.impl.rendezvous.limited.LimitedRangeWalker
 * @see net.jxta.impl.rendezvous.limited.LimitedRangeGreeter
 */

public abstract class RdvGreeter {

    private EndpointListener listener = null;

    /**
     * set an Endpoint Listener for messages received by this greeter
     *
     * @param  listener         An EndpointListener to process the message.
     * @return EndpointListener the old listener. null otherwise.
     */
    public synchronized EndpointListener setEndpointListener(EndpointListener listener) {
        EndpointListener old = this.listener;

        this.listener = listener;
        return old;
    }

    /**
     * get the Endpoint Listener for messages received by this greeter
     *
     * @param  listener         An EndpointListener to process the message.
     * @return EndpointListener current listener. null if no listener was set.
     */
    public synchronized EndpointListener getEndpointListener() {
        return this.listener;
    }

    /**
     * Reply to a message received by the Greeter.
     *
     * @param msg is the source message received previously by the Greeter
     * @param reply is the reply message to be sent to the source of the message.
     * @throws IOException when the reply cannot be sent.
     **/
    public abstract void replyMessage(Message msg, Message reply) throws IOException;

    /**
     ** Start the greeter 
     **/
    public abstract void start();

    /**
     ** Stop the greeter
     **/
    public void stop() {
        listener = null;
    }
}