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/*
 * 
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
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 * Header, with the fields enclosed by brackets [] replaced by your own
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package com.sun.grizzly.comet;

import java.io.IOException;

/**
 * This interface represents a suspended connection (or response). Passing an 
 * instance of this class to {@link CometContext#addCometListener} automatically
 * tells Grizzly Comet to suspend the underlying connection and to avoid commiting the 
 * response. Since the response is not commited, the connection is considered
 * as suspended and can be resumed later when an event happens by invoking 
 * {@link CometContext#resumeCometListener(CometHandler)},
 * from {@link CometHandler#onEvent}. 
 * 
 * {@link CometContext#resumeCometHandler(CometHandler}, 
 * resume the connection by commiting the response. As an example, a browser icons
 * will spins when a connection is suspended, as the complete response hasn't been
 * sent back. 
 * 
 * Components that implement this interface will be notified 
 * {@link CometContext#notify(String)} is invoked or when
 * the {@link CometContext#getExpirationDelay()} expires.
 *
 * With {@link Servlet}, it is recommended to attach the {@link HttpServlerResponse}
 * and use this object to push back messages to the client.
 *
 * @author Jeanfrancois Arcand
 */
public interface CometHandler {

    /**
     * Attach an intance of E to this class.
     */
    public void attach(E attachment);
    
    
    /**
     * Receive {@link CometEvent} notification. This method will be invoked
     * everytime a {@link CometContext#notify} is invoked. The {@link CometEvent}
     * will contains the message that can be pushed back to the remote client,
     * cached or ignored. This method can also be used to resume a connection
     * once a notified by invoking {@link CometContext#resumeCometHandler}.
     */
    public void onEvent(CometEvent event) throws IOException;
    
    
    /**
     * Receive {@link CometEvent} notification when Grizzly is about to
     * suspend the connection. This method is always invoked during the 
     * processing of {@link CometContext#addCometHandler} operations.
     */
    public void onInitialize(CometEvent event) throws IOException;
    
    
    /**
     * Receive {@link CometEvent} notification when the response
     * is resumed by a {@link CometHandler} or by the {@link CometContext}
     */
    public void onTerminate(CometEvent event) throws IOException;    
    
    
    /**
     * Receive {@link CometEvent} notification when the underlying 
     * tcp communication is resumed by Grizzly. This happens
     * when the {@link CometContext#setExpirationDelay} expires or when
     * the remote client close the connection.
     */
    public void onInterrupt(CometEvent event) throws IOException;
    
}