SubscriptionTransferFailed hook not working as expected in Eclipse Milo

Question

I'm trying to manage reconnection to OPC server when it was down for some time and gets started again. My milo client is not able to automatically reconnect because server does not support Subscription transfer, so I added a SusbcriptionListener in order to catch the onSubscriptionTransferFailed event, so I can manually reconnect to the server. The problem seems to be my code is not catching the onSubscriptionTransferFailed event, so I'm not able to know that the server is up again and try to manually reconnect. I tried also with a SessionActivityListener but none event received neither. This is the log file of milo trying to reconnect:

2022-05-19 16:26:59,512 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientAcknowledgeHandler [milo-netty-event-loop-2] Received Acknowledge message on channel=[id: 0x8dc57c76, L:/134.145.242.91:49555 - R:/134.145.242.30:4840].
2022-05-19 16:26:59,513 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-2] OpenSecureChannel timeout scheduled for +5000ms
2022-05-19 16:26:59,513 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler$1 [milo-shared-thread-pool-5] Sent OpenSecureChannelRequest (Issue, id=0, currentToken=-1, previousToken=-1).
2022-05-19 16:26:59,515 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-2] OpenSecureChannel timeout canceled
2022-05-19 16:26:59,515 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-shared-thread-pool-5] Received OpenSecureChannelResponse.
2022-05-19 16:26:59,516 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-shared-thread-pool-5] SecureChannel id=17, currentTokenId=1, previousTokenId=-1, lifetime=3600000ms, createdAt=DateTime{utcTime=116444737603600000, javaDate=Thu Jan 01 01:02:40 CET 1970}
2022-05-19 16:26:59,516 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-2] 0 message(s) queued before handshake completed; sending now.
2022-05-19 16:26:59,516 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-0] [2] S(Reconnecting)          x E(ConnectSuccess)        = S'(Connected)           
2022-05-19 16:26:59,564 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-5] [3] S(ReconnectWait)         x E(ReconnectDelayElapsed) = S'(Reconnecting)        
2022-05-19 16:26:59,567 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientAcknowledgeHandler [milo-netty-event-loop-3] Sent Hello message on channel=[id: 0x311aec0a, L:/134.145.242.91:49556 - R:/134.145.242.30:4840].
2022-05-19 16:26:59,572 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientAcknowledgeHandler [milo-netty-event-loop-3] Received Acknowledge message on channel=[id: 0x311aec0a, L:/134.145.242.91:49556 - R:/134.145.242.30:4840].
2022-05-19 16:26:59,573 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-3] OpenSecureChannel timeout scheduled for +5000ms
2022-05-19 16:26:59,574 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler$1 [milo-shared-thread-pool-0] Sent OpenSecureChannelRequest (Issue, id=0, currentToken=-1, previousToken=-1).
2022-05-19 16:26:59,579 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-3] OpenSecureChannel timeout canceled
2022-05-19 16:26:59,580 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-shared-thread-pool-0] Received OpenSecureChannelResponse.
2022-05-19 16:26:59,580 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-shared-thread-pool-0] SecureChannel id=18, currentTokenId=1, previousTokenId=-1, lifetime=3600000ms, createdAt=DateTime{utcTime=116444737604250000, javaDate=Thu Jan 01 01:02:40 CET 1970}
2022-05-19 16:26:59,581 DEBUG org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-3] 0 message(s) queued before handshake completed; sending now.
2022-05-19 16:26:59,581 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-5] [3] S(Reconnecting)          x E(ConnectSuccess)        = S'(Connected)           
2022-05-19 16:27:14,504 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-0] [5] S(CreatingWait)          x E(CreatingWaitExpired)   = S'(Creating)            
2022-05-19 16:27:14,505 DEBUG org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory [milo-shared-thread-pool-0] [5] Sending CreateSessionRequest...
2022-05-19 16:27:14,512 DEBUG org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory [milo-shared-thread-pool-5] [5] CreateSession succeeded: NodeId{ns=1, id=100016}
2022-05-19 16:27:14,512 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-0] [5] S(Creating)              x E(CreateSessionSuccess)  = S'(Activating)          
2022-05-19 16:27:14,513 DEBUG org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory [milo-shared-thread-pool-0] [5] Sending ActivateSessionRequest...
2022-05-19 16:27:14,516 DEBUG org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory [milo-shared-thread-pool-5] [5] Session activated: OpcUaSession{sessionId=NodeId{ns=1, id=100016}, sessionName=UaSession:Data Capture Automation:1652970434516}
2022-05-19 16:27:14,516 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-0] [5] S(Activating)            x E(ActivateSessionSuccess) = S'(Transferring)        
2022-05-19 16:27:14,517 DEBUG org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory [milo-shared-thread-pool-0] [5] Sending TransferSubscriptionsRequest...
2022-05-19 16:27:14,520 ERROR org.eclipse.milo.opcua.stack.client.transport.uasc.UascClientMessageHandler [milo-netty-event-loop-2] [remote=/134.145.242.30:4840] errorMessage=ErrorMessage{error=StatusCode{name=Bad_ServiceUnsupported, value=0x800B0000, quality=bad}, reason=null}
2022-05-19 16:27:14,522 DEBUG com.digitalpetri.netty.fsm.ChannelFsmFactory$1 [milo-netty-event-loop-2] [2] channelInactive() local=/134.145.242.91:49555, remote=/134.145.242.30:4840
2022-05-19 16:27:14,523 DEBUG com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate [milo-shared-thread-pool-5] [2] S(Connected)             x E(ChannelInactive)       = S'(ReconnectWait)       
2022-05-19 16:27:14,523 DEBUG org.eclipse.milo.opcua.stack.client.UaStackClient [milo-shared-thread-pool-0] sendRequest() failed, request=TransferSubscriptionsRequest, requestHandle=305
java.util.concurrent.CompletionException: UaException: status=Bad_ConnectionClosed, message=connection closed
    at java.util.concurrent.CompletableFuture.encodeRelay(CompletableFuture.java:326)
    at java.util.concurrent.CompletableFuture.completeRelay(CompletableFuture.java:338)
    at java.util.concurrent.CompletableFuture.uniRelay(CompletableFuture.java:925)
    at java.util.concurrent.CompletableFuture$UniRelay.tryFire(CompletableFuture.java:913)

And this is my code to try to catch the onSubscriptionTransferFailed event:

            @Override
            public void onStatusChanged(UaSubscription subscription,
                                        StatusCode status)
            {
                logger.warn("onStatusChanged event for {}, status = {}. Trying to setup new subscription", subscription.toString(), status.toString());
            }

            @Override
            public void onSubscriptionTransferFailed(UaSubscription subscription, StatusCode statusCode) {
                logger.warn("onStatusChanged event for {}, status = {}. Trying to setup new subscription", subscription.toString(), statusCode.toString());
                Stack.sharedExecutor().execute(() -> {
                    try {
                        if(!isConnected()){
                            disconnect();
                            init(endpointUrl, securityPolicy.toString(), "AnonymousProvider");
                        }
                        subscribe(nodesToSubscribe);
                        logger.info("New subscription created");
                    } catch (Exception e) {
                        logger.error("Error creating Subscription: {}", e.getMessage(), e);
                    }
                });
            }
        });

And the SessionActivityListener:

this.client.addSessionActivityListener(new SessionActivityListener() {
            @Override
            public void onSessionInactive(UaSession session) {
                logger.warn("onSessionInactive event for {}. Trying to setup new subscription", session.toString());
            }

            @Override
            public void onSessionActive(UaSession session) {
            }
        });

Could someone tell me if there is something wrong in my code or any clue why I'm not catching the events with those listeners?

Many thanks in advance.

Answer 1

I'm using milo 0.4.3

Due to an implementation defect in this server combined with this issue in Milo's Session FSM pre-0.5.3 you'll need to upgrade the version of Milo your client uses to at least 0.5.3.

I'd recommend just going all the way to 0.6.6, which was just released today. There's no point in moving to an older version.