Wcf – Deploying WCF Services and ‘The resource could not be found’

Actually, although I blogged (see Luke's answer), I think this is better than my IDisposable wrapper. Typical code:

Service<IOrderService>.Use(orderService=>
{
  orderService.PlaceOrder(request);
}); 

(edit per comments)

Since Use returns void, the easiest way to handle return values is via a captured variable:

int newOrderId = 0; // need a value for definite assignment
Service<IOrderService>.Use(orderService=>
  {
    newOrderId = orderService.PlaceOrder(request);
  });
Console.WriteLine(newOrderId); // should be updated

What's likely happening is that SignalData is indirectly changing the subscribers dictionary under the hood during the loop and leading to that message. You can verify this by changing

foreach(Subscriber s in subscribers.Values)

To

foreach(Subscriber s in subscribers.Values.ToList())

If I'm right, the problem will disappear.

Calling subscribers.Values.ToList() copies the values of subscribers.Values to a separate list at the start of the foreach. Nothing else has access to this list (it doesn't even have a variable name!), so nothing can modify it inside the loop.