public async Task Register(With.Component.IIdentity client, With.Component.IEntity entity, IObserver <Message.IMessage> consumer)
{
Registration.IInstance registration = _registrationFactory.For(client, entity, consumer);
_registrations.Add(registration);
await _hub.Register(registration.Client, registration.Entity);
System.Diagnostics.Debug.WriteLine(string.Format("Client Registered '{0}'", registration.Key));
}
