diff --git a/apps/evpnopenflow/src/main/java/org/onosproject/evpnopenflow/rsc/EvpnConstants.java b/apps/evpnopenflow/src/main/java/org/onosproject/evpnopenflow/rsc/EvpnConstants.java
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+++ b/apps/evpnopenflow/src/main/java/org/onosproject/evpnopenflow/rsc/EvpnConstants.java
@@ -0,0 +1,186 @@
+/*
+ * Copyright 2017-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.evpnopenflow.rsc;
+
+/**
+ * Provides constants used in EVPN openflow application.
+ */
+public final class EvpnConstants {
+    private EvpnConstants() {
+    }
+
+    public static final String APP_ID = "org.onosproject.evpnopenflow";
+    public static final String EVPN_OPENFLOW_START = "evpn-openflow app is " +
+            "started";
+    public static final String EVPN_OPENFLOW_STOP = "evpn-openflow app is " +
+            "stopped";
+    public static final String EVPN_VPN_PORT_START = "EVPN port started";
+    public static final String EVPN_VPN_PORT_STOP = "EVPN port stopped";
+    public static final String EVPN_VPN_INSTANCE_START = "EVPN instance " +
+            "started";
+    public static final String EVPN_VPN_INSTANCE_STOP = "EVPN instance " +
+            "stopped";
+    public static final String HOST_DETECT = "Host detected {}";
+    public static final String HOST_VANISHED = "Host vanished {}";
+    public static final String IFACEID = "ifaceid";
+    public static final String IFACEID_OF_HOST_IS_NULL =
+            "The ifaceId of host is null";
+    public static final String CANT_FIND_VPN_PORT = "Can't find vpnport {}";
+    public static final String CANT_FIND_VPN_INSTANCE = "EVPN instance {} is " +
+            "not exist";
+    public static final String CANT_FIND_CONTROLLER_DEVICE = "Can't find " +
+            "controller of device: {}";
+    public static final String GET_PRIVATE_LABEL = "Get private label {}";
+    public static final String RELEASE_LABEL_FAILED = "Release resoure label " +
+            "{} failed";
+    public static final String VPN_PORT_UNBIND = "On EVPN port unbind";
+    public static final String VPN_PORT_BIND = "On EVPN port bind";
+    public static final String SLASH = "/";
+    public static final String COMMA = ",";
+    public static final String VPN_INSTANCE_TARGET = "VpnService";
+    public static final String VPN_PORT_TARGET = "VpnBinding";
+    public static final String BASEPORT = "Port";
+    public static final String VPN_AF_TARGET = "VpnAfConfig";
+    public static final String BGP_PEERING = "BGPPeering";
+    public static final String DATA_PLANE_TUNNEL = "DataplaneTunnel";
+    public static final String VPN_PORT_STORE = "evpn-port-store";
+    public static final String BASE_PORT_STORE = "evpn-baseport-store";
+    public static final String VPN_INSTANCE_STORE =
+            "evpn-instance-store";
+    public static final String VPN_PORT_ID_NOT_NULL = "EVPN port ID cannot be" +
+            " null";
+    public static final String VPN_PORT_NOT_NULL = "EVPN port cannot be null";
+    public static final String RESPONSE_NOT_NULL = "JsonNode can not be null";
+    public static final String LISTENER_NOT_NULL = "Listener cannot be null";
+    public static final String EVENT_NOT_NULL = "Event cannot be null";
+    public static final String DELETE = "delete";
+    public static final String SET = "set";
+    public static final String UPDATE = "update";
+    public static final String VPN_PORT_ID = "EVPN port ID is  {} ";
+    public static final String VPN_PORT_CREATION_FAILED = "The EVPN port " +
+            "creation is failed whose identifier is {} ";
+    public static final String VPN_PORT_IS_NOT_EXIST = "The EVPN port is not " +
+            "exist whose identifier is {}";
+    public static final String VPN_PORT_UPDATE_FAILED = "The EVPN port update" +
+            " is failed whose identifier is {}";
+    public static final String VPN_PORT_DELETE_FAILED =
+            "The EVPN port delete is failed whose identifier is {}";
+    public static final String INTERFACE_ID = "interface_id";
+    public static final String ID = "id";
+    public static final String VPN_INSTANCE = "service_id";
+    public static final String VPN_INSTANCE_ID_NOT_NULL = "EVPN instance ID " +
+            "cannot be null";
+    public static final String VPN_INSTANCE_NOT_NULL = "EVPN instance cannot " +
+            "be null";
+    public static final String JSON_NOT_NULL = "JsonNode can not be null";
+    public static final String INSTANCE_ID = "EVPN instance ID is  {} ";
+    public static final String VPN_INSTANCE_CREATION_FAILED = "The " +
+            "EVPN instance creation is failed whose identifier is {} ";
+    public static final String VPN_INSTANCE_IS_NOT_EXIST = "The EVPN instance" +
+            " is not exist whose identifier is {}";
+    public static final String VPN_INSTANCE_UPDATE_FAILED = "The EVPN " +
+            "instance update is failed whose identifier is {}";
+    public static final String VPN_INSTANCE_DELETE_FAILED = "The EVPN " +
+            "instance delete is failed whose identifier is {}";
+    public static final String VPN_INSTANCE_NAME = "name";
+    public static final String DESCRIPTION = "description";
+    public static final String ROUTE_DISTINGUISHERS = "route_distinguishers";
+    public static final String IPV4_FAMILY = "ipv4_family";
+    static final String ID_CANNOT_BE_NULL = "ID cannot be null";
+    static final String INSTANCE_NAME_CANNOT_BE_NULL = "Instance name cannot " +
+            "be null";
+    static final String DESCRIPTION_CANNOT_BE_NULL = "Description cannot be " +
+            "null";
+    static final String RD_CANNOT_BE_NULL = "RouteDistinguisher cannot be null";
+    static final String RT_CANNOT_BE_NULL = "RouteTarget cannot be null";
+    static final String VPNINSTANCE_NAME = "vpnInstanceName";
+    static final String ROUTE_DISTINGUISHER = "routeDistinguisher";
+    static final String VPN_INSTANCE_ID_CANNOT_BE_NULL = "EVPN instance ID " +
+            "cannot be null";
+    static final String VPN_INSTANCE_ID = "vpnInstanceId";
+    public static final String FORMAT_VPN_INSTANCE = "Id=%s, description=%s,"
+            + " name=%s, routeDistinguisher=%s, routeTarget=%s";
+    public static final String FORMAT_VPN_PORT = "   EVPN port id=%-32s, " +
+            "EVPN instance id=%-18s";
+    public static final String FORMAT_PRIVATE_ROUTE = "   %-18s %-15s %-10s";
+    public static final String FORMAT_PUBLIC_ROUTE = "   %-18s %-18s %-10s";
+    public static final String SWITCH_CHANNEL_ID = "channelId";
+    public static final String NOT_MASTER_FOR_SPECIFIC_DEVICE = "The local " +
+            "controller is not master for the specified deviceId";
+    public static final String VPN_AF_CONFIG_STORE =
+            "evpn-vpn-af-config-store";
+    public static final String EVPN_VPN_AF_CONFIG_START = "EVPN af config" +
+            " started";
+    public static final String EVPN_VPN_AF_CONFIG_STOP = "EVPN af config" +
+            " stopped";
+    static final String RT_TYPE_CANNOT_BE_NULL = "Route target type " +
+            "cannot be null";
+    public static final String VPN_AF_CONFIG_NOT_NULL = "EVPN af config be " +
+            "null";
+    public static final String ROUTE_TARGET_VALUE = "Route target value is {} ";
+    public static final String VPN_AF_CONFIG_CREATION_FAILED = "The " +
+            "EVPN af config creation is failed whose route target is {} ";
+    public static final String VPN_AF_CONFIG_UPDATE_FAILED = "The EVPN af " +
+            "config update is failed whose identifier is {}";
+    public static final String VPN_AF_CONFIG_IS_NOT_EXIST = "The EVPN AF " +
+            "config is not exist whose identifier is {}";
+    public static final String ROUTE_TARGET_CANNOT_NOT_NULL = "Route target " +
+            "value cannot be null";
+    public static final String ROUTE_TARGET_DELETE_FAILED = "The route target" +
+            " delete is failed whose route target value is {}";
+    static final String EXPORT_RT_CANNOT_BE_NULL = "export route " +
+            "target set cannot be null";
+    static final String IMPORT_RT_CANNOT_BE_NULL = "import route " +
+            "target set cannot be null";
+    static final String CONFIG_RT_CANNOT_BE_NULL = "import route " +
+            "target set cannot be null";
+    public static final String EXPORT_EXTCOMMUNITY = "export_extcommunity";
+    public static final String IMPORT_EXTCOMMUNITY = "import_extcommunity";
+    public static final String BOTH = "both";
+    public static final String INVALID_ROUTE_TARGET_TYPE
+            = "Invalid route target type has received";
+    public static final String INVALID_EVENT_RECEIVED
+            = "Invalid event is received while processing network " +
+            "configuration event";
+    public static final String NETWORK_CONFIG_EVENT_IS_RECEIVED
+            = "Event is received from network configuration {}";
+    public static final int ARP_PRIORITY = 0xffff;
+    public static final short ARP_RESPONSE = 0x2;
+    public static final String INVALID_TARGET_RECEIVED
+            = "Invalid target type has received";
+    public static final String INVALID_ACTION_VPN_AF_CONFIG
+            = "Invalid action is received while processing VPN af" +
+            " configuration";
+    public static final String EXPORT_ROUTE_POLICY = "export_route_policy";
+    public static final String IMPORT_ROUTE_POLICY = "import_route_policy";
+    public static final String VRF_RT_TYPE = "vrf_rt_type";
+    public static final String VRF_RT_VALUE = "vrf_rt_value";
+    public static final String BGP_EVPN_ROUTE_UPDATE_START
+            = "bgp evpn route update start {}";
+    public static final String MPLS_OUT_FLOWS = "mpls out flows --> {}";
+    public static final String BGP_EVPN_ROUTE_DELETE_START
+            = "bgp route delete start {}";
+    public static final String ROUTE_ADD_ARP_RULES = "Route ARP Rules-->ADD";
+    public static final String ROUTE_REMOVE_ARP_RULES
+            = "Route ARP Rules-->REMOVE";
+    public static final String TUNNEL_DST = "tunnelDst";
+    public static final String FAILED_TO_SET_TUNNEL_DST
+            = "Failed to get extension instruction to set tunnel dst {}";
+    public static final String VXLAN = "vxlan";
+    public static final String CANNOT_FIND_TUNNEL_PORT_DEVICE =
+            "Can't find tunnel port in device {}";
+}