peergroup.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: PeerGroup.java,v 1.40 2002/06/18 20:45:57 hamada Exp $
 */

package net.jxta.peergroup;


import net.jxta.discovery.DiscoveryService;
import net.jxta.document.Advertisement;
import net.jxta.document.Element;
import net.jxta.endpoint.EndpointService;
import net.jxta.exception.ServiceNotFoundException;
import net.jxta.exception.PeerGroupException;
import net.jxta.exception.ProtocolNotSupportedException;
import net.jxta.exception.JxtaError;
import net.jxta.id.ID;
import net.jxta.id.IDFactory;
import net.jxta.membership.MembershipService;
import net.jxta.peer.PeerID;
import net.jxta.peer.PeerInfoService;
import net.jxta.peergroup.PeerGroupID;
import net.jxta.pipe.PipeService;
import net.jxta.platform.JxtaLoader;
import net.jxta.platform.Module;
import net.jxta.platform.ModuleClassID;
import net.jxta.platform.ModuleSpecID;
import net.jxta.protocol.PeerAdvertisement;
import net.jxta.protocol.PeerGroupAdvertisement;
import net.jxta.protocol.ModuleImplAdvertisement;
import net.jxta.rendezvous.RendezVousService;
import net.jxta.resolver.ResolverService;
import net.jxta.service.Service;

import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;
import java.net.UnknownServiceException;
import java.lang.ClassNotFoundException;
import java.lang.ref.WeakReference;
import java.util.HashMap;

/**
 * Peer groups are formed
 * as a collection of peers that have agreed upon a common set of services.
 * Each peer group is assigned a unique peer group ID and a peer group
 * advertisement. The peer group advertisement contains a ModuleSpecID
 * which refers to a module specification for this peer group.
 *
 * <p>The peer group specification mandates each of the group services (membership,
 * discovery, resolver, etc). Implementations of that specification are
 * described by ModuleImplAdvertisements which are identified by the group's
 * ModuleSpecID. Implementations are responsible for providing the services mandated
 * by the specification.
 *
 * The java reference implementation achieves
 * this by loading additional Modules which ModuleSpecIDs are listed by the group
 * implementation advertisement.
 *
 * <p>In order to participate in a group, a peer needs to join the group
 * using the peer group membership service.
 *
 * <p> JXTA comes with two subclasses of peer groups:
 *
 * <ul type-disc> 
 *
 * <li> <strong>Platform</strong>: this is used to represent the <em>World</em>
 * group. Every peer, when booting, becomes part of this group. This group
 * provides the minimum core services needed to find and instantiate other
 * groups on a peer. <strong>Platform</strong> has the privilege of assigning
 * a new ID to the peer, if it does not already have one. The <em>World</em>
 * group's ID is invariant.</li>
 *
 * <li> <strong>StdPeergroup</strong>: this is currently used to implement
 * all other kinds of peer groups.
 * The first such group that is instantiated after booting is known as
 * <em>The Net Peer Group</em>. When <strong>Platform</strong> starts it may
 * optionaly search for <em>The Net Peer Group</em> on the local network and,
 * if found, instantiate it. Otherwise a default configuration of
 * <em>The Net Peer Group</em> is instanciated.
 *
 * A non-default configuration of <em>The Net Peer Group</em> may be set-up
 * by the administrator in charge of the network domain inside which the peer
 * is booting. <em>The Net Peer Group</em> is discovered via the DiscoveryService
 * protocol. Many such groups may be configured by an administrator.<br>
 *
 * <strong>StdPeergroup</strong> may also be used to implement User-defined
 * peer groups: Users can create new peer groups which use their own set of
 * customized services.
 *</li>
 *</ul>
 *
 * @see         net.jxta.peergroup.PeerGroupID
 * @see         net.jxta.service.Service
 * @see         net.jxta.peergroup.PeerGroupFactory
 * @see         net.jxta.protocol.PeerGroupAdvertisement
 * @see         net.jxta.protocol.ModuleImplAdvertisement
 * @see         net.jxta.platform.ModuleSpecID
 * @see         net.jxta.platform.ModuleClassID
 *
 * @version $Revision: 1.40 $
 * @since JXTA 1.0 */


public interface PeerGroup extends Service {

	/**
	 * Look for needed ModuleImplAdvertisement in this group.
	 */
	public static final int Here = 0;

	/**
	 * Look for needed ModuleImplAdvertisement in the parent group of this group.
	 */
	public static final int FromParent = 1;

	/**
	 * Look for needed ModuleImplAdvertisement in both this group and its parent.
	 */
	public static final int Both = 2;

	/**
	 * Default life time for group advertisements in the publisher's cache.
	 * (a year)
	 */
	public static final long   DEFAULT_LIFETIME = 1000 * 3600 * 24 * 365;

	/**
	 * Default expiration time for discovered group advertisements. (2 weeks)
	 */
	public static final long   DEFAULT_EXPIRATION = 1000 * 3600 * 24 * 14;

	/*
	 * Global registry of instanciated groups.
	 */
	class GlobalRegistry {

		private HashMap registry = new HashMap(8);

		/**
		 * Registers a new instance.
		 * @param gid the ID of the group of which an instance is being registered.
		 * @param pg the group instance being registered.
		 * @return false if the instance could not be registered because there
		 * was already such an instance registered.
		 */
		public synchronized boolean
		registerInstance(PeerGroupID gid, PeerGroup pg) {

			WeakReference ref = (WeakReference) registry.get(gid);

			if ((ref != null) && (ref.get() != null)) return false;

			// If the ref is a dead instance, we can also replace it.
			registry.put(gid, new WeakReference(pg));
			return true;
		}

		/**
		 * Unregisters a group instance (normaly because the grou is being
		 * stopped.
		 *
		 * @param gid the ID of the group of which an instance is unregistered.
		 * @param pg the group instance itself (serves as a creadential).
		 * @return false if the group could not be unregistered because no such
		 * registration (exact ID, exact object) was not found.
		 */
		public synchronized boolean
		unRegisterInstance(PeerGroupID gid, PeerGroup pg) {

			WeakReference ref = (WeakReference) registry.get(gid);
			if (ref == null) return false;

			PeerGroup found = (PeerGroup) ref.get();

			if (found == null) {
				// Dead instance. Remove from table.
				registry.remove(gid);
				return false;
			}

			// Note the use of "!=", not "!equals()"
			if (pg != found) return false;

			registry.remove(gid);
			return true;
		}

		/**
		 * Returns a running instance of the peergroup with given ID if any
		 * exists.
		 * @param gid the id of the group of which an instance is wanted.
		 * @return the group, or null if no instance exists.
		 */
		public synchronized PeerGroup lookupInstance(PeerGroupID gid) {

			WeakReference ref = (WeakReference) registry.get(gid);
			if (ref == null) return null;

			PeerGroup pg = (PeerGroup) ref.get();

			if (pg == null) {
				// Dead instance. remove from table.
				registry.remove(gid);
				return null;
			}

			// Returns an interface object. Therefore a module that got the
			// peergroup through lookup cannot unregister it if the group
			// protects itself by returning an interface object different from
			// the group object. In general only the group itself can
			// unregister when being torn down. Unregistration will also be
			// automatic if the grp object is GC'ed (the references are weak
			// references).
			return (PeerGroup) pg.getInterface();
		}
	}




	/**
	 * An inner class used to create static well-known identifiers.
	 */
	class IdMaker {

		// This method serves to catch the MalformedURLException.
		// Don't know how to catch it from the static init context.
		static ID mkID( String s ) {
		    try {
			return IDFactory.fromURL(IDFactory.jxtaURL( "urn", "", "jxta:uuid-" + s));
		    } catch (MalformedURLException absurd) {
			throw new JxtaError( "Hardcoded Spec and Class IDs are malformed." + s );
		    } catch (UnknownServiceException absurd3) {
			throw new JxtaError( "Unknown Service");
		    }
		}
	}

	/**
	 * Well known classes for the basic services.
	 * FIXME: we should make a "well-known ID" encoding implementation that
	 * has its own little name space of human readable names...later.
	 * To keep their string representation shorter, we put our small spec
	 * or role pseudo unique ID at the front of the second UUID string.
	 * Base classes do not need an explicit second UUID string because it is
	 * all 0.
	 * The type is always the last two characters, nomatter the total length.
	 */

	/**
	 * Well known module class identifier: peer group
	 */
	public static final ModuleClassID peerGroupClassID = (ModuleClassID)
	        IdMaker.mkID( "DeadBeefDeafBabaFeedBabe00000001"
	                      + "05" );

	/**
	 * Well known module class identifier: resolver service