peergroupadvertisement.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/*
 *  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: PeerGroupAdvertisement.java,v 1.37 2005/11/04 19:11:35 bondolo Exp $
 */
package net.jxta.protocol;


import java.util.Iterator;
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 serviceParams = new HashMap();
    
    /**
     *  Returns the identifying type of this Advertisement.
     *
     *@return    String the type of advertisement
     */
    public static String getAdvertisementType() {
        return "jxta:PGA";
    }
    
    /**
     *  {@inheritDoc}
     */
    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.
     */
    public Object clone() {
        try {
            PeerGroupAdvertisement clone = (PeerGroupAdvertisement) super.clone();
            
            clone.setPeerGroupID(getPeerGroupID());
            clone.setModuleSpecID(getModuleSpecID());
            clone.setName(getName());
            clone.setDesc(getDesc());
            clone.setServiceParams(getServiceParams());
            
            return clone;
        } catch (CloneNotSupportedException impossible) {
            return null;
        }  
    }
    
    /**
     *  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.
     */
    
    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 params) {
        serviceParams.clear();
        
        if (params == null) {
            return;
        }
        
        Iterator services = params.entrySet().iterator();

        while (services.hasNext()) {
            Map.Entry anEntry = (Map.Entry) services.next();
            
            Element e = (Element) anEntry.getValue();
            Element 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 getServiceParams() {
        Hashtable copy = new Hashtable();
        
        Iterator services = serviceParams.entrySet().iterator();

        while (services.hasNext()) {
            Map.Entry anEntry = (Map.Entry) services.next();
            
            Element e = (Element) anEntry.getValue();
            Element 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;
        }
        Element 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) {
        Element param = (Element) serviceParams.get(key);

        if (param == null) {
            return null;
        }
        
        StructuredDocument newDoc = StructuredDocumentUtils.copyAsDocument(param);

        return newDoc;
    }
    
    /**
     *  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 = (Element) 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.
        
        StructuredDocument newDoc = StructuredDocumentUtils.copyAsDocument(param);

        return newDoc;
    }
}