Initial implementation of XMPP Publish/Subscribe

Change-Id: I9930056b83004fa7a085f72f63ba973f9ec2d95b
diff --git a/protocols/xmpp/pubsub/api/src/main/java/org/onosproject/xmpp/pubsub/model/XmppPublish.java b/protocols/xmpp/pubsub/api/src/main/java/org/onosproject/xmpp/pubsub/model/XmppPublish.java
new file mode 100644
index 0000000..97dc2a7
--- /dev/null
+++ b/protocols/xmpp/pubsub/api/src/main/java/org/onosproject/xmpp/pubsub/model/XmppPublish.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.onosproject.xmpp.pubsub.model;
+
+import org.dom4j.Element;
+import org.xmpp.packet.IQ;
+
+/**
+ * Abstracts Publish message of XMPP PubSub protocol.
+ */
+public class XmppPublish extends IQ {
+
+    private String jabberId;
+    private String nodeID;
+    private Element item;
+    private String itemID;
+    private Element itemEntry;
+    private String itemEntryNamespace;
+
+    /**
+     * Constructor for XmppPublish class.
+     * @param iq XMPP IQ stanza, which XmppPublish is based on.
+     */
+    public XmppPublish(IQ iq) {
+        super(iq.getElement());
+        this.jabberId = this.fromJID.toString();
+        this.nodeID = this.getChildElement().element("publish").attribute("node").getValue();
+        this.item = this.getChildElement().element("publish").element("item");
+        this.itemID = this.item.attribute("id").getValue();
+        this.itemEntry = this.item.element("entry");
+        this.itemEntryNamespace = this.itemEntry.getNamespaceURI();
+    }
+
+    public String getJabberId() {
+        return this.jabberId;
+    }
+
+    public String getNodeID() {
+        return this.nodeID;
+    }
+
+    public Element getItem() {
+        return this.item;
+    }
+
+    public String getItemID() {
+        return this.itemID;
+    }
+
+    public Element getItemEntry() {
+        return this.itemEntry;
+    }
+
+    public String getItemEntryNamespace() {
+        return this.itemEntryNamespace;
+    }
+
+    @Override
+    public String toString() {
+        return "Publish{" +
+                "JID=" + fromJID +
+                "NodeID=" + this.getNodeID() +
+                "Item=\n" + this.getItem().asXML() +
+                '}';
+    }
+
+}