CORD-131 Added XOS vtn service and port APIs

Change-Id: Ide34212eeb593af5af8db218c6dd2af7d5ab4eaa
diff --git a/apps/xosclient/src/main/java/org/onosproject/xosclient/impl/DefaultVtnPortApi.java b/apps/xosclient/src/main/java/org/onosproject/xosclient/impl/DefaultVtnPortApi.java
new file mode 100644
index 0000000..672c81f
--- /dev/null
+++ b/apps/xosclient/src/main/java/org/onosproject/xosclient/impl/DefaultVtnPortApi.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2016-present Open Networking Laboratory
+ *
+ * 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.xosclient.impl;
+
+import org.onosproject.xosclient.api.VtnPort;
+import org.onosproject.xosclient.api.VtnPortApi;
+import org.onosproject.xosclient.api.VtnPortId;
+import org.onosproject.xosclient.api.VtnServiceId;
+import org.onosproject.xosclient.api.XosAccess;
+
+import java.util.Set;
+
+/**
+ * Provides CORD VTN port APIs.
+ */
+public class DefaultVtnPortApi extends XosApi implements VtnPortApi {
+
+    /**
+     * Default constructor.
+     *
+     * @param baseUrl base url
+     * @param access xos access
+     */
+    public DefaultVtnPortApi(String baseUrl, XosAccess access) {
+        super(baseUrl, access);
+    }
+
+    @Override
+    public Set<VtnPort> vtnPorts() {
+        // TODO implement this when XOS provides this information
+        return null;
+    }
+
+    @Override
+    public Set<VtnPort> vtnPorts(VtnServiceId serviceId) {
+        // TODO implement this when XOS provides this information
+        return null;
+    }
+
+    @Override
+    public VtnPort vtnPort(VtnPortId portId) {
+        // TODO implement this when XOS provides this information
+        return null;
+    }
+}