def register(actor, prefix)
      raise ArgumentError, "#{actor.inspect} is not a RightScale::Actor subclass instance" unless RightScale::Actor === actor
      log_msg = "[actor] #{actor.class.to_s}"
      log_msg += ", prefix #{prefix}" if prefix && !prefix.empty?
      Log.info(log_msg)
      prefix ||= actor.class.default_prefix
      @actors[prefix.to_s] = actor
    end
def register(actor, prefix)
      raise ArgumentError, "#{actor.inspect} is not a RightScale::Actor subclass instance" unless RightScale::Actor === actor
      log_msg = "[actor] #{actor.class.to_s}"
      log_msg += ", prefix #{prefix}" if prefix && !prefix.empty?
      Log.info(log_msg)
      prefix ||= actor.class.default_prefix
      @actors[prefix.to_s] = actor
    end
Initialize registry
 Register as an actor

 === Parameters
 actor(Actor):: Actor to be registered
 prefix(String):: Prefix used in request to identify actor

 === Return
 (Actor):: Actor registered

 === Raises
 ArgumentError if actor is not an Actor