message.java

pastry的java实现的2.0b版

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"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

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package rice.p2p.commonapi;

import java.io.*;

/**
 * @(#) Message.java This interface is an abstraction of a message which is sent
 * through the common API-based system.
 *
 * @version $Id: Message.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 * @author Peter Druschel
 */
public interface Message extends Serializable {

  // different priority levels
  /**
   * DESCRIBE THE FIELD
   */
  public final static byte MAX_PRIORITY = 0;
  /**
   * DESCRIBE THE FIELD
   */
  public final static byte HIGH_PRIORITY = 5;
  /**
   * DESCRIBE THE FIELD
   */
  public final static byte MEDIUM_HIGH_PRIORITY = 10;
  /**
   * DESCRIBE THE FIELD
   */
  public final static byte MEDIUM_PRIORITY = 15;
  /**
   * DESCRIBE THE FIELD
   */
  public final static byte MEDIUM_LOW_PRIORITY = 20;
  /**
   * DESCRIBE THE FIELD
   */
  public final static byte LOW_PRIORITY = 25;

  /**
   * Method which should return the priority level of this message. The messages
   * can range in priority from 0 (highest priority) to Integer.MAX_VALUE
   * (lowest) - when sending messages across the wire, the queue is sorted by
   * message priority. If the queue reaches its limit, the lowest priority
   * messages are discarded. Thus, applications which are very verbose should
   * have LOW_PRIORITY or lower, and applications which are somewhat quiet are
   * allowed to have MEDIUM_PRIORITY or possibly even HIGH_PRIORITY.
   *
   * @return This message's priority
   */
  public byte getPriority();

}