scribetutorial.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.tutorial.lesson6;

import java.net.*;
import java.util.*;

import rice.environment.Environment;
import rice.p2p.commonapi.NodeHandle;
import rice.pastry.*;
import rice.pastry.socket.SocketPastryNodeFactory;
import rice.pastry.standard.RandomNodeIdFactory;

/**
 * This tutorial shows how to use Scribe.
 *
 * @version $Id: pretty.settings 2305 2005-03-11 20:22:33Z jeffh $
 * @author Jeff Hoye
 */
public class ScribeTutorial {

  /**
   * this will keep track of our Scribe applications
   */
  Vector apps = new Vector();

  /**
   * Based on the rice.tutorial.lesson4.DistTutorial This constructor launches
   * numNodes PastryNodes. They will bootstrap to an existing ring if one exists
   * at the specified location, otherwise it will start a new ring.
   *
   * @param bindport the local port to bind to
   * @param bootaddress the IP:port of the node to boot from
   * @param numNodes the number of nodes to create in this JVM
   * @param env the Environment
   * @exception Exception DESCRIBE THE EXCEPTION
   */
  public ScribeTutorial(int bindport, InetSocketAddress bootaddress,
                        int numNodes, Environment env) throws Exception {

    // Generate the NodeIds Randomly
    NodeIdFactory nidFactory = new RandomNodeIdFactory(env);

    // construct the PastryNodeFactory, this is how we use rice.pastry.socket
    PastryNodeFactory factory = new SocketPastryNodeFactory(nidFactory,
      bindport, env);

    // loop to construct the nodes/apps
    for (int curNode = 0; curNode < numNodes; curNode++) {
      // This will return null if we there is no node at that location
      rice.pastry.NodeHandle bootHandle = ((SocketPastryNodeFactory) factory)
        .getNodeHandle(bootaddress);

      // construct a node, passing the null boothandle on the first loop will
      // cause the node to start its own ring
      PastryNode node = factory.newNode(bootHandle);

      // the node may require sending several messages to fully boot into the
      // ring
      while (!node.isReady()) {
        // delay so we don't busy-wait
        Thread.sleep(100);
      }

      System.out.println("Finished creating new node: " + node);

      // construct a new scribe application
      MyScribeClient app = new MyScribeClient(node);
      apps.add(app);
    }

    // for the first app subscribe then start the publishtask
    Iterator i = apps.iterator();
    MyScribeClient app = (MyScribeClient) i.next();
    app.subscribe();
    app.startPublishTask();
    // for all the rest just subscribe
    while (i.hasNext()) {
      app = (MyScribeClient) i.next();
      app.subscribe();
    }

    // now, print the tree
    Thread.sleep(5000);
    printTree(apps);
  }

  /**
   * Recursively crawl up the tree to find the root.
   *
   * @param seed DESCRIBE THE PARAMETER
   * @param appTable DESCRIBE THE PARAMETER
   * @return The Root value
   */
  public static NodeHandle getRoot(NodeHandle seed, Hashtable appTable) {
    MyScribeClient app = (MyScribeClient) appTable.get(seed);
    if (app.isRoot()) {
      return seed;
    }
    NodeHandle nextSeed = app.getParent();
    return getRoot(nextSeed, appTable);
  }

  /**
   * Note that this function only works because we have global knowledge. Doing
   * this in an actual distributed environment will take some more work.
   *
   * @param apps Vector of the applicatoins.
   */
  public static void printTree(Vector apps) {
    // build a hashtable of the apps, keyed by nodehandle
    Hashtable appTable = new Hashtable();
    Iterator i = apps.iterator();
    while (i.hasNext()) {
      MyScribeClient app = (MyScribeClient) i.next();
      appTable.put(app.endpoint.getLocalNodeHandle(), app);
    }
    NodeHandle seed = ((MyScribeClient) apps.get(0)).endpoint
      .getLocalNodeHandle();

    // get the root
    NodeHandle root = getRoot(seed, appTable);

    // print the tree from the root down
    recursivelyPrintChildren(root, 0, appTable);
  }

  /**
   * Print's self, then children.
   *
   * @param curNode DESCRIBE THE PARAMETER
   * @param recursionDepth DESCRIBE THE PARAMETER
   * @param appTable DESCRIBE THE PARAMETER
   */
  public static void recursivelyPrintChildren(NodeHandle curNode,
                                              int recursionDepth, Hashtable appTable) {
    // print self at appropriate tab level
    String s = "";
    for (int numTabs = 0; numTabs < recursionDepth; numTabs++) {
      s += "  ";
    }
    s += curNode.getId().toString();
    System.out.println(s);

    // recursively print all children
    MyScribeClient app = (MyScribeClient) appTable.get(curNode);
    NodeHandle[] children = app.getChildren();
    for (int curChild = 0; curChild < children.length; curChild++) {
      recursivelyPrintChildren(children[curChild], recursionDepth + 1, appTable);
    }
  }

  /**
   * Usage: java [-cp FreePastry- <version>.jar]
   * rice.tutorial.lesson6.ScribeTutorial localbindport bootIP bootPort numNodes
   * example java rice.tutorial.DistTutorial 9001 pokey.cs.almamater.edu 9001
   *
   * @param args The command line arguments
   * @exception Exception DESCRIBE THE EXCEPTION
   */
  public static void main(String[] args) throws Exception {
    // Loads pastry configurations
    Environment env = new Environment();

    try {
      // the port to use locally
      int bindport = Integer.parseInt(args[0]);

      // build the bootaddress from the command line args
      InetAddress bootaddr = InetAddress.getByName(args[1]);
      int bootport = Integer.parseInt(args[2]);
      InetSocketAddress bootaddress = new InetSocketAddress(bootaddr, bootport);

      // the port to use locally
      int numNodes = Integer.parseInt(args[3]);

      // launch our node!
      ScribeTutorial dt = new ScribeTutorial(bindport, bootaddress, numNodes,
        env);
    } catch (Exception e) {
      // remind user how to use
      System.out.println("Usage:");
      System.out.println("java [-cp FreePastry-<version>.jar] rice.tutorial.lesson6.ScribeTutorial localbindport bootIP bootPort numNodes");
      System.out.println("example java rice.tutorial.DistTutorial 9001 pokey.cs.almamater.edu 9001 10");
      throw e;
    }
  }
}