diff --git a/common/transport/lwm2m/src/main/java/org/thingsboard/server/transport/lwm2m/server/session/DefaultLwM2MSessionManager.java b/common/transport/lwm2m/src/main/java/org/thingsboard/server/transport/lwm2m/server/session/DefaultLwM2MSessionManager.java
index ee6e4a779b..a9198f9fcd 100644
--- a/common/transport/lwm2m/src/main/java/org/thingsboard/server/transport/lwm2m/server/session/DefaultLwM2MSessionManager.java
+++ b/common/transport/lwm2m/src/main/java/org/thingsboard/server/transport/lwm2m/server/session/DefaultLwM2MSessionManager.java
@@ -19,7 +19,6 @@ import lombok.extern.slf4j.Slf4j;
 import org.springframework.context.annotation.Lazy;
 import org.springframework.stereotype.Service;
 import org.thingsboard.server.common.transport.TransportService;
-import org.thingsboard.server.common.transport.service.DefaultTransportService;
 import org.thingsboard.server.gen.transport.TransportProtos;
 import org.thingsboard.server.queue.util.TbLwM2mTransportComponent;
 import org.thingsboard.server.transport.lwm2m.server.LwM2mSessionMsgListener;
@@ -27,6 +26,11 @@ import org.thingsboard.server.transport.lwm2m.server.attributes.LwM2MAttributesS
 import org.thingsboard.server.transport.lwm2m.server.rpc.LwM2MRpcRequestHandler;
 import org.thingsboard.server.transport.lwm2m.server.uplink.LwM2mUplinkMsgHandler;
 
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SESSION_EVENT_MSG_CLOSED;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SESSION_EVENT_MSG_OPEN;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SUBSCRIBE_TO_ATTRIBUTE_UPDATES_ASYNC_MSG;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SUBSCRIBE_TO_RPC_ASYNC_MSG;
+
 @Slf4j
 @Service
 @TbLwM2mTransportComponent
@@ -52,16 +56,16 @@ public class DefaultLwM2MSessionManager implements LwM2MSessionManager {
         transportService.registerAsyncSession(sessionInfo, new LwM2mSessionMsgListener(uplinkHandler, attributesService, rpcHandler, sessionInfo, transportService));
         TransportProtos.TransportToDeviceActorMsg msg = TransportProtos.TransportToDeviceActorMsg.newBuilder()
                 .setSessionInfo(sessionInfo)
-                .setSessionEvent(DefaultTransportService.getSessionEventMsg(TransportProtos.SessionEvent.OPEN))
-                .setSubscribeToAttributes(TransportProtos.SubscribeToAttributeUpdatesMsg.newBuilder().setSessionType(TransportProtos.SessionType.ASYNC).build())
-                .setSubscribeToRPC(TransportProtos.SubscribeToRPCMsg.newBuilder().setSessionType(TransportProtos.SessionType.ASYNC).build())
+                .setSessionEvent(SESSION_EVENT_MSG_OPEN)
+                .setSubscribeToAttributes(SUBSCRIBE_TO_ATTRIBUTE_UPDATES_ASYNC_MSG)
+                .setSubscribeToRPC(SUBSCRIBE_TO_RPC_ASYNC_MSG)
                 .build();
         transportService.process(msg, null);
     }
 
     @Override
     public void deregister(TransportProtos.SessionInfoProto sessionInfo) {
-        transportService.process(sessionInfo, DefaultTransportService.getSessionEventMsg(TransportProtos.SessionEvent.CLOSED), null);
+        transportService.process(sessionInfo, SESSION_EVENT_MSG_CLOSED, null);
         transportService.deregisterSession(sessionInfo);
     }
 }
diff --git a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java
index fe39721f27..c99b4e1a45 100644
--- a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java
+++ b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/MqttTransportHandler.java
@@ -65,7 +65,6 @@ import org.thingsboard.server.common.transport.service.SessionMetaData;
 import org.thingsboard.server.common.transport.util.SslUtil;
 import org.thingsboard.server.gen.transport.TransportProtos;
 import org.thingsboard.server.gen.transport.TransportProtos.ProvisionDeviceResponseMsg;
-import org.thingsboard.server.gen.transport.TransportProtos.SessionEvent;
 import org.thingsboard.server.gen.transport.TransportProtos.ValidateDeviceX509CertRequestMsg;
 import org.thingsboard.server.queue.scheduler.SchedulerComponent;
 import org.thingsboard.server.transport.mqtt.adaptors.MqttTransportAdaptor;
@@ -102,6 +101,8 @@ import static io.netty.handler.codec.mqtt.MqttMessageType.UNSUBACK;
 import static io.netty.handler.codec.mqtt.MqttQoS.AT_LEAST_ONCE;
 import static io.netty.handler.codec.mqtt.MqttQoS.AT_MOST_ONCE;
 import static io.netty.handler.codec.mqtt.MqttQoS.FAILURE;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SESSION_EVENT_MSG_CLOSED;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SESSION_EVENT_MSG_OPEN;
 
 /**
  * @author Andrew Shvayka
@@ -929,7 +930,7 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
     public void doDisconnect() {
         if (deviceSessionCtx.isConnected()) {
             log.debug("[{}] Client disconnected!", sessionId);
-            transportService.process(deviceSessionCtx.getSessionInfo(), DefaultTransportService.getSessionEventMsg(SessionEvent.CLOSED), null);
+            transportService.process(deviceSessionCtx.getSessionInfo(), SESSION_EVENT_MSG_CLOSED, null);
             transportService.deregisterSession(deviceSessionCtx.getSessionInfo());
             if (gatewaySessionHandler != null) {
                 gatewaySessionHandler.onGatewayDisconnect();
@@ -948,7 +949,7 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
             deviceSessionCtx.setDeviceInfo(msg.getDeviceInfo());
             deviceSessionCtx.setDeviceProfile(msg.getDeviceProfile());
             deviceSessionCtx.setSessionInfo(SessionInfoCreator.create(msg, context, sessionId));
-            transportService.process(deviceSessionCtx.getSessionInfo(), DefaultTransportService.getSessionEventMsg(SessionEvent.OPEN), new TransportServiceCallback<Void>() {
+            transportService.process(deviceSessionCtx.getSessionInfo(), SESSION_EVENT_MSG_OPEN, new TransportServiceCallback<Void>() {
                 @Override
                 public void onSuccess(Void msg) {
                     SessionMetaData sessionMetaData = transportService.registerAsyncSession(deviceSessionCtx.getSessionInfo(), MqttTransportHandler.this);
diff --git a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/GatewaySessionHandler.java b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/GatewaySessionHandler.java
index 7b45b5f9d9..cb984327da 100644
--- a/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/GatewaySessionHandler.java
+++ b/common/transport/mqtt/src/main/java/org/thingsboard/server/transport/mqtt/session/GatewaySessionHandler.java
@@ -44,7 +44,6 @@ import org.thingsboard.server.common.transport.adaptor.JsonConverter;
 import org.thingsboard.server.common.transport.adaptor.ProtoConverter;
 import org.thingsboard.server.common.transport.auth.GetOrCreateDeviceFromGatewayResponse;
 import org.thingsboard.server.common.transport.auth.TransportDeviceInfo;
-import org.thingsboard.server.common.transport.service.DefaultTransportService;
 import org.thingsboard.server.gen.transport.TransportApiProtos;
 import org.thingsboard.server.gen.transport.TransportProtos;
 import org.thingsboard.server.gen.transport.TransportProtos.GetOrCreateDeviceFromGatewayRequestMsg;
@@ -68,6 +67,10 @@ import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 
 import static org.springframework.util.ConcurrentReferenceHashMap.ReferenceType;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SESSION_EVENT_MSG_CLOSED;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SESSION_EVENT_MSG_OPEN;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SUBSCRIBE_TO_ATTRIBUTE_UPDATES_ASYNC_MSG;
+import static org.thingsboard.server.common.transport.service.DefaultTransportService.SUBSCRIBE_TO_RPC_ASYNC_MSG;
 
 /**
  * Created by ashvayka on 19.01.17.
@@ -267,11 +270,9 @@ public class GatewaySessionHandler {
                                     transportService.registerAsyncSession(deviceSessionInfo, deviceSessionCtx);
                                     transportService.process(TransportProtos.TransportToDeviceActorMsg.newBuilder()
                                             .setSessionInfo(deviceSessionInfo)
-                                            .setSessionEvent(DefaultTransportService.getSessionEventMsg(TransportProtos.SessionEvent.OPEN))
-                                            .setSubscribeToAttributes(TransportProtos.SubscribeToAttributeUpdatesMsg.newBuilder()
-                                                    .setSessionType(TransportProtos.SessionType.ASYNC).build())
-                                            .setSubscribeToRPC(TransportProtos.SubscribeToRPCMsg.newBuilder()
-                                                    .setSessionType(TransportProtos.SessionType.ASYNC).build())
+                                            .setSessionEvent(SESSION_EVENT_MSG_OPEN)
+                                            .setSubscribeToAttributes(SUBSCRIBE_TO_ATTRIBUTE_UPDATES_ASYNC_MSG)
+                                            .setSubscribeToRPC(SUBSCRIBE_TO_RPC_ASYNC_MSG)
                                             .build(), null);
                                 }
                                 futureToSet.set(devices.get(deviceName));
@@ -720,7 +721,7 @@ public class GatewaySessionHandler {
 
     private void deregisterSession(String deviceName, GatewayDeviceSessionCtx deviceSessionCtx) {
         transportService.deregisterSession(deviceSessionCtx.getSessionInfo());
-        transportService.process(deviceSessionCtx.getSessionInfo(), DefaultTransportService.getSessionEventMsg(TransportProtos.SessionEvent.CLOSED), null);
+        transportService.process(deviceSessionCtx.getSessionInfo(), SESSION_EVENT_MSG_CLOSED, null);
         log.debug("[{}] Removed device [{}] from the gateway session", sessionId, deviceName);
     }
 
diff --git a/common/transport/transport-api/src/main/java/org/thingsboard/server/common/transport/service/DefaultTransportService.java b/common/transport/transport-api/src/main/java/org/thingsboard/server/common/transport/service/DefaultTransportService.java
index 57d1da63b4..98ffcd721e 100644
--- a/common/transport/transport-api/src/main/java/org/thingsboard/server/common/transport/service/DefaultTransportService.java
+++ b/common/transport/transport-api/src/main/java/org/thingsboard/server/common/transport/service/DefaultTransportService.java
@@ -21,7 +21,6 @@ import com.google.common.util.concurrent.MoreExecutors;
 import com.google.gson.Gson;
 import com.google.gson.JsonObject;
 import com.google.protobuf.ByteString;
-import lombok.Getter;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.context.ApplicationEventPublisher;
@@ -124,6 +123,15 @@ import java.util.stream.Collectors;
 public class DefaultTransportService implements TransportService {
 
     public static final String OVERWRITE_ACTIVITY_TIME = "overwriteActivityTime";
+    public static final String SESSION_EXPIRED_MESSAGE = "Session has expired due to last activity time!";
+    public static final TransportProtos.SessionEventMsg SESSION_EVENT_MSG_OPEN = getSessionEventMsg(TransportProtos.SessionEvent.OPEN);
+    public static final TransportProtos.SessionEventMsg SESSION_EVENT_MSG_CLOSED = getSessionEventMsg(TransportProtos.SessionEvent.CLOSED);
+    public static final TransportProtos.SessionCloseNotificationProto SESSION_CLOSE_NOTIFICATION_PROTO = TransportProtos.SessionCloseNotificationProto.newBuilder()
+            .setMessage(SESSION_EXPIRED_MESSAGE).build();
+    public static final TransportProtos.SubscribeToAttributeUpdatesMsg SUBSCRIBE_TO_ATTRIBUTE_UPDATES_ASYNC_MSG = TransportProtos.SubscribeToAttributeUpdatesMsg.newBuilder()
+            .setSessionType(TransportProtos.SessionType.ASYNC).build();
+    public static final TransportProtos.SubscribeToRPCMsg SUBSCRIBE_TO_RPC_ASYNC_MSG = TransportProtos.SubscribeToRPCMsg.newBuilder()
+            .setSessionType(TransportProtos.SessionType.ASYNC).build();
 
     private final AtomicInteger atomicTs = new AtomicInteger(0);
 
@@ -267,9 +275,7 @@ public class DefaultTransportService implements TransportService {
 
     @Override
     public SessionMetaData registerAsyncSession(TransportProtos.SessionInfoProto sessionInfo, SessionMsgListener listener) {
-        SessionMetaData newValue = new SessionMetaData(sessionInfo, TransportProtos.SessionType.ASYNC, listener);
-        SessionMetaData oldValue = sessions.putIfAbsent(toSessionId(sessionInfo), newValue);
-        return oldValue != null ? oldValue : newValue;
+        return sessions.computeIfAbsent(toSessionId(sessionInfo), (x) -> new SessionMetaData(sessionInfo, TransportProtos.SessionType.ASYNC, listener));
     }
 
     @Override
@@ -719,12 +725,8 @@ public class DefaultTransportService implements TransportService {
                     }
                     sessions.remove(uuid);
                     sessionsToRemove.add(uuid);
-                    process(sessionInfo, getSessionEventMsg(TransportProtos.SessionEvent.CLOSED), null);
-                    TransportProtos.SessionCloseNotificationProto sessionCloseNotificationProto = TransportProtos.SessionCloseNotificationProto
-                            .newBuilder()
-                            .setMessage("Session has expired due to last activity time!")
-                            .build();
-                    sessionMD.getListener().onRemoteSessionCloseCommand(uuid, sessionCloseNotificationProto);
+                    process(sessionInfo, SESSION_EVENT_MSG_CLOSED, null);
+                    sessionMD.getListener().onRemoteSessionCloseCommand(uuid, SESSION_CLOSE_NOTIFICATION_PROTO);
                 }
             } else {
                 if (lastActivityTime > sessionAD.getLastReportedActivityTime()) {
@@ -1018,7 +1020,7 @@ public class DefaultTransportService implements TransportService {
         return new DeviceId(new UUID(sessionInfo.getDeviceIdMSB(), sessionInfo.getDeviceIdLSB()));
     }
 
-    public static TransportProtos.SessionEventMsg getSessionEventMsg(TransportProtos.SessionEvent event) {
+    private static TransportProtos.SessionEventMsg getSessionEventMsg(TransportProtos.SessionEvent event) {
         return TransportProtos.SessionEventMsg.newBuilder()
                 .setSessionType(TransportProtos.SessionType.ASYNC)
                 .setEvent(event).build();