/*************************************************************************

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
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- Redistributions of source code must retain the above copyright
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- Redistributions in binary form must reproduce the above copyright
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documentation and/or other materials provided with the distribution.

- Neither  the name  of Rice  University (RICE) 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 RICE and the contributors on an "as is"
basis, without any representations or warranties of any kind, express
or implied including, but not limited to, representations or
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particular purpose. In no event shall RICE or contributors be liable
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********************************************************************************/

package rice.p2p.commonapi;

/**
 * @(#) Application.java Interface which an application must implement in order
 * to run on top of the Node interface.
 *
 * @version $Id: Application.java 2584 2005-06-16 22:03:26Z jeffh $
 * @author Alan Mislove
 * @author Peter Druschel
 */
public interface Application {

  /**
   * This method is invoked on applications when the underlying node is about to
   * forward the given message with the provided target to the specified next
   * hop. Applications can change the contents of the message, specify a
   * different nextHop (through re-routing), or completely terminate the
   * message.
   *
   * @param message The message being sent, containing an internal message along
   *      with a destination key and nodeHandle next hop.
   * @return Whether or not to forward the message further
   */
  public boolean forward(RouteMessage message);

  /**
   * This method is called on the application at the destination node for the
   * given id.
   *
   * @param id The destination id of the message
   * @param message The message being sent
   */
  public void deliver(Id id, Message message);

  /**
   * This method is invoked to inform the application that the given node has
   * either joined or left the neighbor set of the local node, as the set would
   * be returned by the neighborSet call.
   *
   * @param handle The handle that has joined/left
   * @param joined Whether the node has joined or left
   */
  public void update(NodeHandle handle, boolean joined);

}


