publishrequestmessage.java

pastry的java实现的2.0b版

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

"FreePastry" Peer-to-Peer Application Development Substrate 

Copyright 2002, Rice University. All rights reserved.

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

package rice.p2p.scribe.messaging;

import java.io.IOException;

import rice.*;
import rice.p2p.commonapi.*;
import rice.p2p.commonapi.rawserialization.*;
import rice.p2p.scribe.*;
import rice.p2p.scribe.rawserialization.*;

/**
 * @(#) PublishRequestMessage.java The publish message.
 *
 * @version $Id: PublishRequestMessage.java 3274 2006-05-15 16:17:47Z jeffh $
 * @author Alan Mislove
 */
public class PublishRequestMessage extends ScribeMessage {

  // the content of this message
  /**
   * DESCRIBE THE FIELD
   */
  protected RawScribeContent content;
  /**
   * DESCRIBE THE FIELD
   */
  public final static short TYPE = 9;

  /**
   * Constructor which takes a unique integer Id
   *
   * @param source The source address
   * @param topic DESCRIBE THE PARAMETER
   * @param content DESCRIBE THE PARAMETER
   */
  public PublishRequestMessage(NodeHandle source, Topic topic, ScribeContent content) {
    this(source, topic, content instanceof RawScribeContent ? (RawScribeContent) content : new JavaSerializedScribeContent(content));
  }

  /**
   * Constructor for PublishRequestMessage.
   *
   * @param source DESCRIBE THE PARAMETER
   * @param topic DESCRIBE THE PARAMETER
   * @param content DESCRIBE THE PARAMETER
   */
  public PublishRequestMessage(NodeHandle source, Topic topic, RawScribeContent content) {
    super(source, topic);

    this.content = content;
  }

  /**
   * Private because it should only be called from build(), if you need to
   * extend this, make sure to build a serializeHelper() like in
   * AnycastMessage/SubscribeMessage, and properly handle the version number.
   *
   * @param buf DESCRIBE THE PARAMETER
   * @param endpoint DESCRIBE THE PARAMETER
   * @param cd DESCRIBE THE PARAMETER
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  private PublishRequestMessage(InputBuffer buf, Endpoint endpoint, ScribeContentDeserializer cd) throws IOException {
    super(buf, endpoint);

    // this can be done lazilly to be more efficient, must cache remaining bits, endpoint, cd, and implement own InputBuffer
    short contentType = buf.readShort();
    if (contentType == 0) {
      content = new JavaSerializedScribeContent(cd.deserializeScribeContent(buf, endpoint, contentType));
    } else {
      content = (RawScribeContent) cd.deserializeScribeContent(buf, endpoint, contentType);
    }

  }

  /**
   * Returns the content
   *
   * @return The content
   */
  public ScribeContent getContent() {
//  if (content == null)
    if (content.getType() == 0) {
      return ((JavaSerializedScribeContent) content).getContent();
    }
    return content;
  }

  /**
   * Raw Serialization **************************************
   *
   * @return The Type value
   */
  public short getType() {
    return TYPE;
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param buf DESCRIBE THE PARAMETER
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public void serialize(OutputBuffer buf) throws IOException {
    buf.writeByte((byte) 0);
    // version
    super.serialize(buf);

    buf.writeShort(content.getType());
    content.serialize(buf);
  }

  /**
   * DESCRIBE THE METHOD
   *
   * @param buf DESCRIBE THE PARAMETER
   * @param endpoint DESCRIBE THE PARAMETER
   * @param scd DESCRIBE THE PARAMETER
   * @return DESCRIBE THE RETURN VALUE
   * @exception IOException DESCRIBE THE EXCEPTION
   */
  public static PublishRequestMessage build(InputBuffer buf, Endpoint endpoint, ScribeContentDeserializer scd) throws IOException {
    byte version = buf.readByte();
    switch (version) {
      case 0:
        return new PublishRequestMessage(buf, endpoint, scd);
      default:
        throw new IOException("Unknown Version: " + version);
    }
  }
}