Cancel a long running task over WCF from client
.net, c#, long-running-processes, nettcpbinding, wcf
Solution
I have a WCF service set to PerCall
... the problem here is that, each time a call comes to the server, it's treated as a new request.
Yup, that's exactly what you're telling it to do. If you can, just change to `InstanceContextMode.PerSession`; then you can do what you're trying to do (assuming you're self-hosting).
If you can't do this, then you'll have to develop a more complex solution like @PeterRitchie commented. First, your host: IIS is not designed to have long-running operations independent of requests, so I'll assume you're self-hosting. Next, you'll need a form of token (like a GUID) that will act as an identifier for a long-running operation. Your `Start` method will allocate a GUID and `CancellationTokenSource` and start the operation, and your `Stop` method will take a GUID and use that to look up the `CancellationTokenSource` and cancel the operation. You'll need a shared (static, threadsafe) dictionary to act as lookup.
If your host is IIS, then your solution gets more complex... :)
First, you'll need a backend that's not hosted in IIS. Common choices are an Azure worker role or a Win32 service. Next, you'll need a reliable communications mechanism: an Azure queue, MSMQ, WebSphere, etc. Then you can build your WCF-over-IIS service to have the `Start` method generate a GUID identifier and drop a message on the queue to start processing. The `Stop` method takes the GUID and drops a message on the queue to cancel processing. All other logic gets moved to the backend service.
Problem
I have a WCF service set to PerCall I would like to know how I can send a Start call from the client to start a long running process, and send a Cancel command to cancel it My WCF service looks something like this ``` [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)] public class Service1 : IService1 { CancellationTokenSource cancelToken = new CancellationTokenSource(); public void Start() { var compute = Task.Factory.StartNew(StartLongRunningTask, cancelToken.Token); } public void Stop() { cancelToken.Cancel(); } private void StartLongRunningTask() { //process here } } ``` I guess the problem here is that, each time a call comes to the server, it's treated as a new request. So how should starting and cancelling a long running task in WCF be done? EDIT: I'm hosting it as a windows service