Passing client context using Unity in WCF service application

I have a WCF service application (actually, it uses WCF Web API preview 5) that intercepts each request and extracts several header values passed from the client. The idea is that the 'interceptor' will extract these values and setup a ClientContext object that is then globally available within the application for the duration of the request. The server is stateless, so the context is per-call.

My problem is that the application uses IoC (Unity) for dependency injection so there is no use of singleton's, etc. Any class that needs to use the context receives it via DI.

So, how do I 'dynamically' create a new context object for each request and make sure that it is used by the container for the duration of that request? I also need to be sure that it is completely thread开发者_如何学C-safe in that each request is truly using the correct instance.

UPDATE

So I realize as I look into the suggestions below that part of my problem is encapsulation. The idea is that the interface used for the context (IClientContext) contains only read-only properties so that the rest of the application code doesn't have the ability to make changes. (And in a team development environment, if the code allows it, someone will inevitably do it.)

As a result, in my message handler that intercepts the request, I can get an instance of the type implementing the interface from the container but I can't make use of it. I still want to only expose a read-only interface to all other code but need a way to set the property values. Any ideas?

I'm considering implementing two interfaces, one that provides read-only access and one that allows me to initialize the instance. Or casting the resolved object to a type that allows me to set the values. Unfortunately, this isn't fool-proof either but unless someone has a better idea, it might be the best I can do.

Read Andrew Oakley's Blog on WCF specific lifetime managers. He creates a UnityOperationContextLifetimeManager:

we came up with the idea to build a Unity lifetime manager tied to WCF's OperationContext. That way, our container objects would live only for the lifetime of the request...

Configure your context class with that lifetime manager and then just resolve it. It should give you an "operation singleton".

Sounds like you need a Unity LifetimeManager. See this SO question or this MSDN article.