I have a multith-threaded, continusly running application that connects with multiple devices via TCP/IP sockets and exposes a set of WCF API's for controlling, monitoring and reporting on these devices. I would like to host this on IIS for the ususal reasons of not having to worry about re-starting the app in case of errors. So the issue I have is the main application running in parallel with the WCF Servies. To accomplish this I use the static AppInitialize class to start a thread which has the main applicaiton loop. The WCF services mostly report or control the shared objects with this thread. There are two problems that I see with this approach. One is that if the thread dies, IIS has no clue to re-start it so I have to play some tricks with some WCF calls. The other is that the backrgound thread deals with potentially thousands of devices that are connected permanently (typically a thread per socket connection). So I am not sure if IIS is buying me anything in this case. Another approach that I am thinking is to use WF for the main application that deals with the sockets and host both the WF and my WCF services in IIS using AppFabric. Since I have not use WF or AppFabric I am reaching out to see if this would be good approach or there are better alternative.