multiringapplication.java

pastry的java实现的2.0b版

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

"FreePastry" Peer-to-Peer Application Development Substrate 

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package rice.p2p.multiring;

import rice.p2p.commonapi.*;

/**
 * @(#) MultiringApplication.java Application which wraps a real application
 *
 * @version $Id: MultiringApplication.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 * @author Peter Druschel
 */
public class MultiringApplication implements Application {

  /**
   * The app which this mulitring app is wrapping
   */
  protected Application application;

  /**
   * The Id which represents the current ring this app is a member of
   */
  protected Id ringId;

  /**
   * Constructor
   *
   * @param ringId DESCRIBE THE PARAMETER
   * @param application DESCRIBE THE PARAMETER
   */
  protected MultiringApplication(Id ringId, Application application) {
    this.application = application;
    this.ringId = ringId;

    if ((ringId instanceof RingId) || (application instanceof MultiringApplication)) {
      throw new IllegalArgumentException("Illegal creation of MRApplication: " + ringId.getClass() + ", " + application.getClass());
    }
  }

  /**
   * 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) {
    return application.forward(new MultiringRouteMessage(ringId, 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) {
    if (id != null) {
      application.deliver(RingId.build(ringId, id), message);
    } else {
      application.deliver(null, 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) {
    application.update(new MultiringNodeHandle(ringId, handle), joined);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @return DESCRIBE THE RETURN VALUE
   */
  public String toString() {
    return "MultiringApplication<" + application + ">:" + ringId;
  }

}