WCF channel closed in Azure VM when running long operations

Question

Hi!
We are hosting a WCF Service on a Azure VM. Now we have a Problem with a web service method that runs longer than ~ 5 minutes. So the web client calls the method, the service starts some calculations and should return a value. But the problem is that the
channel seems to be closed (by Azure itself?) before we finish the calculation an can return the value. We receive following error message:
System.Net.HttpListenerException: The semaphore timeout period has expired
We are using .NET 4.0 and wsHttpBinding. Any idea what causes this problem or how we could solve it?

Answer 1

Hi Thomas,
Base on my experience, the reason for this is that the Load Balancer of Windows Azure Datacenter will silently tear down any idle connection after 4 minutes. You may need expend Keepalive time. I suggest you could refer to this code sample (http://code.msdn.microsoft.com/WCF-Azure-NetTCP-Keep-Alive-09f50fd9
) about how to keep alive channel. Also, you could refer to this document (http://blogs.msdn.com/b/cie/archive/2014/02/14/connection-timeout-for-windows-azure-cloud-service-roles-web-worker.aspx
Hope this helps.
Regards,
Will
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