Can't use WCF NetPeerTcpBinding in ASP.NET?

Question

I write applications for web farms and I wanted to create a simple peer network between server applications so they could pass messages to each other. For example, to coordinate when dropping cache items, or to increment a shared counter to have a better shared view of a crucial statistic.

But apparently this isn't possible. I had peer-to-peer code working perfectly in a console application, but when I added the code to an ASP.NET website I got the following error:

System event notifications are not supported under the current context. Server processes, for example, may not support global system event notifications.

[InvalidOperationException: System event notifications are not supported under the current context. Server processes, for example, may not support global system event notifications.]
   System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg) +10259418
   System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type) +539
   // My code here where I call the proxy object's method to start the WCF call

Um, why not? It seems like this would be supremely useful!

Is there any way to get around this?

Answer 1

What version of IIS is your service running on (assuming IIS)? IIS 6 is quite a bit more limited than IIS 7 - it only supports HTTP activation. Likewise, if you're trying to start a peer-to-peer client from within IIS 6, it may be blocked for the same reason - IIS can't direct responses to the correct worker process.

You could always implement the service as a Windows service on the web server, and use named pipes to communicate with your ASP.NET site. (The Windows service would host a peer-to-peer endpoint and a named-pipe endpoint, and the site would use a named-pipe client. The service would run as a single instance using the [ServiceBehavior] attribute.

Answer 2

I am not sure this is possible because of the way the binding holds its context.

I would suggest having a normal http wcf service and register each host in a configuration database, or even use a topic and post events that web server needs to process.