current OperationContext is null in WCF Windows Service

Question

I am trying to set up a Publish/Subscribe system using WCF and where the WCF server is in a Windows service. The binding is net.TCP. The service is providing a \"Subscribe

Answer 1

I had a similar issue: in my case when the InstanceContextMode was set to Single the WebOperationContext.Current was null in the constructor. However it was available within the services/classes methods.

Answer 2

In the client code neither proxy created not channel factory. Service class instance is created as a class library.

You should consume service as below code

 ServiceCallback serviceCallback = new ServiceCallback();
 InstanceContext instanceContext = new InstanceContext(serviceCallback);

 var pubsubProxy = new PubSubProxy.WcfPublisherContractClient(instanceContext);
 pubsubProxy.Subscribe();

And when the service is running, OperationContext is created and you can access OperationContext.Current

Answer 3

I've faced this issue and non of the solutions worked and Most Important thing is if you're using

async await 
OperationContext.Current; will be null

My usage is to get Ip so used it like this before any awaitable call

var clientIpAddress = System.Web.HttpContext.Current?.Request?.UserHostAddress;

After the first await statement in your async service operation, OperationContext.Current could be null because the rest of the method body may be running on a different thread (and OperationContext does not flow between threads

So to get it you can write your code before any awaitable action

May be it'll help someone :)

Answer 4

As discussed in the comments, if you directly create an instance of the service type - as opposed to a WCF proxy/clientchannel - and then you call a method on it, there is no OperationContext. WCF provides an OperationContext instance when your operation is running within a service.

Answer 5

In my case it was me being stupid...

I tried to set

 callback = OperationContext.Current.GetCallbackChannel<IWcfSubscriberContract>();

In the CALLBACK function, instead of the server side funciton... When in callback function - obviously there's no current context.