Initial implementation of XMPP Publish/Subscribe

Change-Id: I9930056b83004fa7a085f72f63ba973f9ec2d95b
diff --git a/protocols/xmpp/pubsub/api/src/main/java/org/onosproject/xmpp/pubsub/model/XmppSubscribe.java b/protocols/xmpp/pubsub/api/src/main/java/org/onosproject/xmpp/pubsub/model/XmppSubscribe.java
new file mode 100644
index 0000000..c3040d5
--- /dev/null
+++ b/protocols/xmpp/pubsub/api/src/main/java/org/onosproject/xmpp/pubsub/model/XmppSubscribe.java
@@ -0,0 +1,48 @@
+/*
+ * 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.xmpp.packet.IQ;
+
+/**
+ * Abstracts Subscribe message of XMPP PubSub protocol.
+ */
+public class XmppSubscribe extends IQ {
+
+    private String jabberId;
+    private String nodeID;
+
+    /**
+     * Constructor for XmppSubscribe class.
+     *
+     * @param iq XMPP IQ stanza, which XmppSubscribe is based on.
+     */
+    public XmppSubscribe(IQ iq)  {
+        super(iq.getElement());
+        this.jabberId = this.fromJID.toString();
+        this.nodeID = this.getChildElement().element("subscribe").attribute("node").getValue();
+    }
+
+    public String getJabberId() {
+        return this.jabberId;
+    }
+
+    public String getNodeID() {
+        return this.nodeID;
+    }
+
+}