public LocPocSubscription(LocationMessageService messageService)
 {
     Name = "Subscription";
     AddField(new EventStreamFieldType
     {
         Name       = "locationAdded",
         Type       = typeof(LocationAddedMessageType),
         Resolver   = new FuncFieldResolver <LocationAddedMessage>(c => c.Source as LocationAddedMessage),
         Subscriber = new EventStreamResolver <LocationAddedMessage>(c => messageService.GetMessages())
     });
 }