Disconnection issues with azure service bus relay

Question

We are running some long-running test apps with Azure Service Bus relay over http, hosted in a windows service and most of the time, these run fine for 2-3 days. However every so often an internal network glich may occur (e.g. firewall reboots) that kills the internet connection.

At this point, the relay is dropped in Azure and our web app can no longer communicate with the on-premise service.

I would have thought that the Azure relay client was fault-tolerant - in that if it realises that it's lost connection with Azure then it will re-establish the connection andf if it can't keep trying until it can.. but it appears that this is not the case. This seems pretty fundamental...?

Only once have I ever seen a "System.ServiceModel.CommunicationException" where the service can't communicate on the internet, and that was when the client was starting up and trying to establish the connection in the first place.

Is there any advice or feedback on handling transient disconnections through the relay service (as it's a cloud --> on-prem direction then the client can't AFAIK ping the server).

Answer 1

If you are still experiencing issues, you may want to contact Azure support to understand why it is disconnecting. The Relay client should reconnect if something happens to the existing connection.

You may want to add ConnectionStatusBehavior to your ChannelFactory to have it output when the status for the connection changes. It will contain the error that caused it to change status.

var connectionStatusBehavior = new ConnectionStatusBehavior();
connectionStatusBehavior.Online += ConnectionStatusOnlineMethod;
connectionStatusBehavior.Offline += ConnectionStatusOfflineMethod;
channelFactory.Endpoint.Behaviors.Add(connectionStatusBehavior);

Answer 2

This issue is solved by Microsoft in version 2.6.5 of Microsoft Azure Service Bus dll. After 1 month of testing it seems to work.