diff --git a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/Constants.java b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/Constants.java
index b59307e..6475a7a 100644
--- a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/Constants.java
+++ b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/Constants.java
@@ -18,6 +18,7 @@
 import com.google.common.collect.ImmutableMap;
 import org.onlab.packet.MacAddress;
 
+import java.nio.charset.StandardCharsets;
 import java.util.Map;
 
 /**
@@ -41,6 +42,11 @@
 
     public static final String OPENSTACK_NETWORKING_APP_ID =
                                             "org.onosproject.openstacknetworking";
+    public static final String OPENSTACK_NETWORKING_REST_PATH = "onos/openstacknetworking";
+    public static final int REST_PORT = 8181;
+    public static final String REST_USER = "onos";
+    public static final String REST_PASSWORD = "rocks";
+    public static final String REST_UTF8 = StandardCharsets.UTF_8.name();
 
     public static final String ARP_BROADCAST_MODE = "broadcast";
     public static final String ARP_PROXY_MODE = "proxy";
diff --git a/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackHaService.java b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackHaService.java
new file mode 100644
index 0000000..2b39179
--- /dev/null
+++ b/apps/openstacknetworking/api/src/main/java/org/onosproject/openstacknetworking/api/OpenstackHaService.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2019-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.openstacknetworking.api;
+
+import org.onlab.packet.IpAddress;
+
+/**
+ * Handles openstack mastership.
+ */
+public interface OpenstackHaService {
+
+    /**
+     * Indicates the active-standby status.
+     *
+     * @return true if the the node runs in active mode, false otherwise
+     */
+    boolean isActive();
+
+    /**
+     * Obtains the IP address of the active node.
+     *
+     * @return IP address of the active node
+     */
+    IpAddress getActiveIp();
+
+    /**
+     * Configures the IP address of the active node.
+     *
+     * @param ip  IP address of the active node
+     */
+    void setActiveIp(IpAddress ip);
+
+    /**
+     * Configures the active status.
+     *
+     * @param flag true if the node runs in active mode, false otherwise
+     */
+    void setActive(boolean flag);
+}