Smack/source/org/jivesoftware/smackx/ServiceDiscoveryManager.java

/**
* $RCSfile$
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* $Date$
*
* Copyright (C) 2002-2003 Jive Software. All rights reserved.
* ====================================================================
* The Jive Software License (based on Apache Software License, Version 1.1)
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* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
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* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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*    the documentation and/or other materials provided with the
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* 3. The end-user documentation included with the redistribution,
*    if any, must include the following acknowledgment:
*       "This product includes software developed by
*        Jive Software (http://www.jivesoftware.com)."
*    Alternately, this acknowledgment may appear in the software itself,
*    if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Smack" and "Jive Software" must not be used to
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*
* 5. Products derived from this software may not be called "Smack",
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package org.jivesoftware.smackx;

import java.util.*;

import org.jivesoftware.smack.*;
import org.jivesoftware.smack.filter.*;
import org.jivesoftware.smack.packet.*;
import org.jivesoftware.smackx.packet.*;

/**
 * Manages discovery of services in XMPP entities. This class provides:
 * <ol>
 * <li>A registry of supported features in this XMPP entity.
 * <li>Automatic response when this XMPP entity is queried for information.
 * <li>Ability to discover items and information of remote XMPP entities.
 * <li>Ability to publish publicly available items.
 * </ol>  
 * 
 * @author Gaston Dombiak
 */
public class ServiceDiscoveryManager {
    
    private static Map instances = new Hashtable();
    
    private XMPPConnection connection;
    private List features = new ArrayList();
    
    // Create a new ServiceDiscoveryManager on every established connection
    static {
        XMPPConnection.addConnectionListener(new ConnectionEstablishedListener() {
            public void connectionEstablished(XMPPConnection connection) {
                new ServiceDiscoveryManager(connection);
            }
        });
    }

    /**
     * Creates a new ServiceDiscoveryManager for a given XMPPConnection. This means that the 
     * service manager will respond to any service discovery request that the connection may
     * receive. 
     * 
     * @param connection the connection to which a ServiceDiscoveryManager is going to be created
     */
    public ServiceDiscoveryManager(XMPPConnection connection) {
        this.connection = connection;
        init();
    }

    /**
     * Returns the ServiceDiscoveryManager instance associated with a given XMPPConnection.
     * 
     * @param connection the connection used to look for the proper ServiceDiscoveryManager
     * @return the ServiceDiscoveryManager associated with a given XMPPConnection
     */
    public static ServiceDiscoveryManager getInstanceFor(XMPPConnection connection) {
        return (ServiceDiscoveryManager)instances.get(connection);
    }
    
    /**
     * Initializes the packet listeners of the connection that will answer to any
     * service discovery request. 
     */
    private void init() {
        // Register the new instance and associate it with the connection 
        instances.put(connection, this);
        // Add a listener to the connection that removes the registered instance when
        // the connection is closed
        connection.addConnectionListener(new ConnectionListener() {
            public void connectionClosed() {
                // Unregister this instance since the connection has been closed
                instances.remove(connection);
            }
            
            public void connectionClosedOnError(Exception e) {
                // Unregister this instance since the connection has been closed
                instances.remove(connection);
            }
        });
        
        // Listen for disco#items requests and answer with an empty result        
        PacketFilter packetFilter = new PacketTypeFilter(DiscoverItems.class);
        PacketListener packetListener = new PacketListener() {
            public void processPacket(Packet packet) {
                DiscoverItems discoverItems = (DiscoverItems) packet;
                // Answer an empty result if the request is of the GET type
                // Note: In a future version Smack will enable to have items defined in the client 
                if (discoverItems != null && discoverItems.getType() == IQ.Type.GET) {
                    DiscoverItems response = new DiscoverItems();
                    response.setType(IQ.Type.RESULT);
                    response.setTo(discoverItems.getFrom());
                    response.setPacketID(discoverItems.getPacketID());
                    connection.sendPacket(response);
                }
            }
        };
        connection.addPacketListener(packetListener, packetFilter);

        // Listen for disco#info requests and answer the client's supported features 
        // To add a new feature as supported use the #addFeature message        
        packetFilter = new PacketTypeFilter(DiscoverInfo.class);
        packetListener = new PacketListener() {
            public void processPacket(Packet packet) {
                DiscoverInfo discoverInfo = (DiscoverInfo) packet;
                // Answer the client's supported features if the request is of the GET type
                if (discoverInfo != null && discoverInfo.getType() == IQ.Type.GET) {
                    DiscoverInfo response = new DiscoverInfo();
                    response.setType(IQ.Type.RESULT);
                    response.setTo(discoverInfo.getFrom());
                    response.setPacketID(discoverInfo.getPacketID());
                    // Add the registered features to the response
                    synchronized (features) {
                        for (Iterator it=getFeatures(); it.hasNext();) {
                            response.addFeature((String) it.next());
                        }
                    }
                    connection.sendPacket(response);
                }
            }
        };
        connection.addPacketListener(packetListener, packetFilter);
    }

    /**
     * Returns the supported features by this XMPP entity.
     * 
     * @return an Iterator on the supported features by this XMPP entity
     */
    public Iterator getFeatures() {
        synchronized (features) {
            return Collections.unmodifiableList(new ArrayList(features)).iterator();
        }
    }
    
    /**
     * Registers that a new feature is supported by this XMPP entity. When this client is 
     * queried for its information the registered features will be answered. 
     *
     * @param feature the feature to register as supported
     */
    public void addFeature(String feature) {
        synchronized (features) {
            features.add(feature);
        }
    }

    /**
     * Removes the specified feature from the supported features by this XMPP entity.
     *
     * @param feature the feature to remove from the supported features
     */
    public void removeFeature(String feature) {
        synchronized (features) {
            features.remove(feature);
        }
    }

    /**
     * Returns true if the specified feature is registered in the ServiceDiscoveryManager.
     *
     * @param feature the feature to look for
     * @return a boolean indicating if the specified featured is registered or not
     */
    public boolean includesFeature(String feature) {
        synchronized (features) {
            return features.contains(feature);
        }
    }

    /**
     * Returns the discovered information of a given XMPP entity addressed by its JID.
     * 
     * @param entityID the address of the XMPP entity
     * @return the discovered information
     * @throws XMPPException if the operation failed for some reason
     */
    public DiscoverInfo discoverInfo(String entityID) throws XMPPException {
        return discoverInfo(entityID, null);
    }
    
    /**
     * Returns the discovered information of a given XMPP entity addressed by its JID and
     * note attribute. Use this message only when trying to query information which is not 
     * directly addressable.
     * 
     * @param entityID the address of the XMPP entity
     * @param node the attribute that supplements the 'jid' attribute
     * @return the discovered information
     * @throws XMPPException if the operation failed for some reason
     */
    public DiscoverInfo discoverInfo(String entityID, String node) throws XMPPException {
        // Discover the entity's info
        DiscoverInfo disco = new DiscoverInfo();
        disco.setType(IQ.Type.GET);
        disco.setTo(entityID);
        disco.setNode(node);

        // Create a packet collector to listen for a response.
        PacketCollector collector =
            connection.createPacketCollector(new PacketIDFilter(disco.getPacketID()));

        connection.sendPacket(disco);

        // Wait up to 5 seconds for a result.
        IQ result = (IQ) collector.nextResult(5000);
        if (result == null) {
            throw new XMPPException("No response from the server.");
        }
        if (result.getType() == IQ.Type.ERROR) {
            throw new XMPPException(result.getError());
        }
        return (DiscoverInfo) result;
    }

    /**
     * Returns the discovered items of a given XMPP entity addressed by its JID.
     * 
     * @param entityID the address of the XMPP entity
     * @return the discovered information
     * @throws XMPPException if the operation failed for some reason
     */
    public DiscoverItems discoverItems(String entityID) throws XMPPException {
        return discoverItems(entityID, null);
    }
    
    /**
     * Returns the discovered items of a given XMPP entity addressed by its JID and
     * note attribute. Use this message only when trying to query information which is not 
     * directly addressable.
     * 
     * @param entityID the address of the XMPP entity
     * @param node the attribute that supplements the 'jid' attribute
     * @return the discovered items
     * @throws XMPPException if the operation failed for some reason
     */
    public DiscoverItems discoverItems(String entityID, String node) throws XMPPException {
        // Discover the entity's items
        DiscoverItems disco = new DiscoverItems();
        disco.setType(IQ.Type.GET);
        disco.setTo(entityID);
        disco.setNode(node);

        // Create a packet collector to listen for a response.
        PacketCollector collector =
            connection.createPacketCollector(new PacketIDFilter(disco.getPacketID()));

        connection.sendPacket(disco);

        // Wait up to 5 seconds for a result.
        IQ result = (IQ) collector.nextResult(5000);
        if (result == null) {
            throw new XMPPException("No response from the server.");
        }
        if (result.getType() == IQ.Type.ERROR) {
            throw new XMPPException(result.getError());
        }
        return (DiscoverItems) result;
    }

    /**
     * Publishes new items to a parent entity. The item elements to publish MUST have at least 
     * a 'jid' attribute specifying the Entity ID of the item, and an action attribute which 
     * specifies the action being taken for that item. Possible action values are: "update" and 
     * "remove".
     * 
     * @param entityID the address of the XMPP entity
     * @param discoverItems the DiscoveryItems to publish
     * @throws XMPPException if the operation failed for some reason
     */
    public void publishItems(String entityID, DiscoverItems discoverItems) throws XMPPException {
        discoverItems.setType(IQ.Type.SET);
        discoverItems.setTo(entityID);
        
        // Create a packet collector to listen for a response.
        PacketCollector collector =
            connection.createPacketCollector(new PacketIDFilter(discoverItems.getPacketID()));

        connection.sendPacket(discoverItems);

        // Wait up to 5 seconds for a result.
        IQ result = (IQ) collector.nextResult(5000);
        if (result == null) {
            throw new XMPPException("No response from the server.");
        }
        if (result.getType() == IQ.Type.ERROR) {
            throw new XMPPException(result.getError());
        }
    }
}