001/**
002 *
003 * Copyright the original author or authors
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smackx.pubsub;
018
019import org.jivesoftware.smack.packet.Message;
020import org.jivesoftware.smack.packet.ExtensionElement;
021import org.jivesoftware.smackx.pubsub.provider.ItemProvider;
022
023/**
024 * This class represents an item that has been, or will be published to a
025 * pubsub node.  An <tt>Item</tt> has several properties that are dependent
026 * on the configuration of the node to which it has been or will be published.
027 * 
028 * <h3>An Item received from a node (via {@link LeafNode#getItems()} or {@link LeafNode#addItemEventListener(org.jivesoftware.smackx.pubsub.listener.ItemEventListener)}</h3>
029 * <ul>
030 * <li>Will always have an id (either user or server generated) unless node configuration has both
031 * {@link ConfigureForm#isPersistItems()} and {@link ConfigureForm#isDeliverPayloads()}set to false.</li>
032 * <li>Will have a payload if the node configuration has {@link ConfigureForm#isDeliverPayloads()} set 
033 * to true, otherwise it will be null.</li>
034 * </ul>
035 * 
036 * <h3>An Item created to send to a node (via {@link LeafNode#send()} or {@link LeafNode#publish()}</h3>
037 * <ul>
038 * <li>The id is optional, since the server will generate one if necessary, but should be used if it is 
039 * meaningful in the context of the node.  This value must be unique within the node that it is sent to, since
040 * resending an item with the same id will overwrite the one that already exists if the items are persisted.</li>
041 * <li>Will require payload if the node configuration has {@link ConfigureForm#isDeliverPayloads()} set
042 * to true.</li>
043 * </ul>
044 * 
045 * <p>To customise the payload object being returned from the {@link #getPayload()} method, you can
046 * add a custom parser as explained in {@link ItemProvider}.</p>
047 * 
048 * @author Robin Collier
049 */
050public class PayloadItem<E extends ExtensionElement> extends Item
051{
052    private E payload;
053
054    /**
055     * Create an <tt>Item</tt> with no id and a payload  The id will be set by the server.  
056     * 
057     * @param payloadExt A {@link ExtensionElement} which represents the payload data.
058     */
059    public PayloadItem(E payloadExt)
060    {
061        super();
062
063        if (payloadExt == null)
064            throw new IllegalArgumentException("payload cannot be 'null'");
065        payload = payloadExt;
066    }
067
068    /**
069     * Create an <tt>Item</tt> with an id and payload.  
070     * 
071     * @param itemId The id of this item.  It can be null if we want the server to set the id.
072     * @param payloadExt A {@link ExtensionElement} which represents the payload data.
073     */
074    public PayloadItem(String itemId, E payloadExt)
075    {
076        super(itemId);
077
078        if (payloadExt == null)
079            throw new IllegalArgumentException("payload cannot be 'null'");
080        payload = payloadExt;
081    }
082
083    /**
084     * Create an <tt>Item</tt> with an id, node id and payload.  
085     * 
086     * <p>
087     * <b>Note:</b> This is not valid for publishing an item to a node, only receiving from 
088     * one as part of {@link Message}.  If used to create an Item to publish 
089     * (via {@link LeafNode#publish(Item)}, the server <i>may</i> return an
090     * error for an invalid packet.
091     * </p>
092     * 
093     * @param itemId The id of this item.
094     * @param nodeId The id of the node the item was published to.
095     * @param payloadExt A {@link ExtensionElement} which represents the payload data.
096     */
097    public PayloadItem(String itemId, String nodeId, E payloadExt)
098    {
099        super(itemId, nodeId);
100
101        if (payloadExt == null)
102            throw new IllegalArgumentException("payload cannot be 'null'");
103        payload = payloadExt;
104    }
105
106    /**
107     * Get the payload associated with this <tt>Item</tt>.  Customising the payload
108     * parsing from the server can be accomplished as described in {@link ItemProvider}.
109     * 
110     * @return The payload as a {@link ExtensionElement}.
111     */
112    public E getPayload()
113    {
114        return payload;
115    }
116
117    @Override
118    public String toXML()
119    {
120        StringBuilder builder = new StringBuilder("<item");
121
122        if (getId() != null)
123        {
124            builder.append(" id='");
125            builder.append(getId());
126            builder.append('\'');
127        }
128
129        if (getNode() != null) {
130            builder.append(" node='");
131            builder.append(getNode());
132            builder.append('\'');
133        }
134        builder.append('>');
135        builder.append(payload.toXML());
136        builder.append("</item>");
137
138        return builder.toString();
139    }
140
141    @Override
142    public String toString()
143    {
144        return getClass().getName() + " | Content [" + toXML() + "]";
145    }
146}