peergroupadvertisement.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  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 Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     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, 
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 *  
 *  JXTA is a registered trademark of Sun Microsystems, Inc. in the United 
 *  States and other countries.
 *  
 *  Please see the license information page at :
 *  <http://www.jxta.org/project/www/license.html> for instructions on use of 
 *  the license in source files.
 *  
 *  ====================================================================
 *  
 *  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. 
 */

package net.jxta.protocol;


import java.util.Hashtable;
import java.util.Map;
import java.util.HashMap;

import net.jxta.document.Element;
import net.jxta.document.ExtendableAdvertisement;
import net.jxta.document.MimeMediaType;
import net.jxta.document.StructuredDocument;
import net.jxta.document.StructuredDocumentFactory;
import net.jxta.document.StructuredDocumentUtils;
import net.jxta.id.ID;
import net.jxta.peergroup.PeerGroupID;
import net.jxta.platform.ModuleSpecID;


/**
 *  Describes a peer group and references additional information required for
 *  instantiating it. The PeerGroup method newGroup performs the task of
 *  instantiating a PeerGroup given its advertisement (provided the required
 *  subsequent documents can actually be found). This advertisement is indexed
 *  on "Name", "GID", and "Desc"
 *
 *  @see    net.jxta.platform.ModuleSpecID
 *  @see    net.jxta.protocol.ModuleImplAdvertisement
 *  @see    net.jxta.peergroup.PeerGroup
 */

public abstract class PeerGroupAdvertisement extends ExtendableAdvertisement implements Cloneable {
    
    private PeerGroupID gid = null;
    private ModuleSpecID specId = null;
    
    /**
     *  Informal, non-canonical name of this peer group
     */
    private String name = null;
    
    /**
     * Descriptive meta-data about this peer group.
     */
    private Element description = null;
    
    // A table of structured documents to be interpreted by each service.
    private final Map<ID, StructuredDocument> serviceParams = new HashMap<ID, StructuredDocument>();
    
    /**
     *  Returns the identifying type of this Advertisement.
     *
     *@return    String the type of advertisement
     */
    public static String getAdvertisementType() {
        return "jxta:PGA";
    }
    
    /**
     *  {@inheritDoc}
     */
    @Override
    public final String getBaseAdvType() {
        return getAdvertisementType();
    }
    
    /**
     *  Construct a new Peer Group Advertisement.
     **/
    public PeerGroupAdvertisement() {}
    
    /**
     *  {@inheritDoc}
     *
     *@return An object of class PeerGroupAdvertisement that is a
     *      deep-enough copy of this one.
     */
    @Override
    public PeerGroupAdvertisement clone() {
    
        PeerGroupAdvertisement clone;

        try {
            clone = (PeerGroupAdvertisement) super.clone();
        } catch (CloneNotSupportedException impossible) {
            throw new Error("Object.clone() threw CloneNotSupportedException", impossible);
        }  
            
        clone.setPeerGroupID(getPeerGroupID());
        clone.setModuleSpecID(getModuleSpecID());
        clone.setName(getName());
        clone.setDesc(getDesc());
        clone.setServiceParams(getServiceParams());

        return clone;
    }
    
    /**
     *  Returns the name of the group or <tt>null</tt> if no name has been
     *  assigned.
     *
     *@return    String name of the group.
     */
    
    public String getName() {
        return name;
    }
    
    /**
     *  sets the name of the group.
     *
     *@param  name  name of the group.
     */
    
    public void setName(String name) {
        this.name = name;
    }

    /**
     *  Returns the id of the group spec that this uses.
     *
     *@return    ID the spec id
     */
    
    public ModuleSpecID getModuleSpecID() {
        return specId;
    }
    
    /**
     *  Sets the id of the group spec that this peer group uses.
     *
     *@param  sid  The id of the spec
     */
    
    public void setModuleSpecID(ModuleSpecID sid) {
        this.specId = sid;
    }
    
    /**
     *  Returns the id of the group.
     *
     *@return    ID the group id
     */
    
    public PeerGroupID getPeerGroupID() {
        return gid;
    }
    
    /**
     *  Sets the id of the group.
     *
     *@param  gid  The id of this group.
     */
    
    public void setPeerGroupID(PeerGroupID gid) {
        this.gid = gid;
    }
    
    /**
     *  Returns a unique ID for indexing purposes. We use the id of the group as
     *  a plain ID.
     *
     *@return    ID a unique id for that advertisement.
     */
    
    @Override
    public ID getID() {
        return gid;
    }
    
    /**
     * returns the description
     *
     * @return String the description
     */
    public String getDescription() {
        if (null != description) {
            return (String) description.getValue();
        } else {
            return null;
        }
    }
    
    /**
     * sets the description
     *
     * @param description the description
     */
    public void setDescription(String description) {
        
        if (null != description) {
            StructuredDocument newdoc = StructuredDocumentFactory.newStructuredDocument(MimeMediaType.XMLUTF8, "Desc", description);
            
            setDesc(newdoc);
        } else {
            this.description = null;
        }
    }
    
    /**
     * returns the description
     *
     * @return the description
     */
    public StructuredDocument getDesc() {
        if (null != description) {
            StructuredDocument newDoc = StructuredDocumentUtils.copyAsDocument(description);
            
            return newDoc;
        } else {
            return null;
        }
    }
    
    /**
     * sets the description
     *
     * @since JXTA 1.0
     *
     * @param desc the description
     *
     */
    public void setDesc(Element desc) {
        
        if (null != desc) {
            this.description = StructuredDocumentUtils.copyAsDocument(desc);
        } else {
            this.description = null;
        }
    }
    
    /**
     *  sets the sets of parameters for all services. This method first makes a
     *  deep copy, in order to protect the active information from uncontrolled
     *  sharing. This quite an expensive operation. If only a few of the
     *  parameters need to be added, it is wise to use putServiceParam()
     *  instead.
     *
     *@param  params  The whole set of parameters.
     */
    public void setServiceParams(Hashtable<ID, ? extends Element> params) {
        serviceParams.clear();
        
        if (params == null) {
            return;
        }

        for (Map.Entry<ID, ? extends Element> anEntry : params.entrySet()) {
            Element e = anEntry.getValue();
            StructuredDocument newDoc = StructuredDocumentUtils.copyAsDocument(e);

            serviceParams.put(anEntry.getKey(), newDoc);
        }

    }
    
    /**
     *  Returns the sets of parameters for all services. 
     *
     *  <p/>This method returns a deep copy, in order to protect the real
     *  information from uncontrolled sharing while keeping it shared as long as
     *  it is safe. This quite an expensive operation. If only a few parameters
     *  need to be accessed, it is wise to use getServiceParam() instead.
     *
     *@return    all of the parameters.
     */
    public Hashtable<ID, StructuredDocument> getServiceParams() {
        Hashtable<ID, StructuredDocument> copy = new Hashtable<ID, StructuredDocument>();

        for (Map.Entry<ID, StructuredDocument> anEntry : serviceParams.entrySet()) {
            Element e = anEntry.getValue();
            StructuredDocument newDoc = StructuredDocumentUtils.copyAsDocument(e);

            copy.put(anEntry.getKey(), newDoc);
        }

        return copy;
    }
    
    /**
     *  Puts a service parameter in the service parameters table under the given
     *  key. The key is of a subclass of ID; usually a ModuleClassID. This
     *  method makes a deep copy of the given element into an independent
     *  document.
     *
     *@param  key    The key.
     *@param  param  The parameter, as an element. What is stored is a copy as a
     *      standalone StructuredDocument which type is the element's name.
     */
    public void putServiceParam(ID key, Element param) {
        if (param == null) {
            serviceParams.remove(key);
            return;
        }
        
        StructuredDocument newDoc = StructuredDocumentUtils.copyAsDocument(param);

        serviceParams.put(key, newDoc);        
    }
    
    /**
     *  Returns the parameter element that matches the given key from the
     *  service parameters table. The key is of a subclass of ID; usually a
     *  ModuleClassID.
     *
     *@param  key  The key.
     *@return      StructuredDocument The matching parameter document or null if
     *      none matched. The document type id "Param".
     */
    public StructuredDocument getServiceParam(ID key) {
        StructuredDocument param = serviceParams.get(key);

        if (param == null) {
            return null;
        }
        
        return  StructuredDocumentUtils.copyAsDocument(param);
    }
    
    /**
     *  Removes and returns the parameter element that matches the given key
     *  from the service parameters table. The key is of a subclass of ID;
     *  usually a ModuleClassID.
     *
     *@param  key  The key.
     *@return      Element the removed parameter element or null if not found.
     *      This is actually a StructureDocument of type "Param".
     */
    public StructuredDocument removeServiceParam(ID key) {
        Element param = serviceParams.remove(key);

        if (param == null) {
            return null;
        }
                      
        // It sound silly to clone it, but remember that we could be sharing
        // this element with a clone of ours, so we have the duty to still
        // protect it.
        
        return StructuredDocumentUtils.copyAsDocument(param);
    }
}