3.6.2 Consideration for distributed systems

For distributed systems, references become meaningless. From this consideration, messages are uniformly transmitted by value. So the identifier of a message is unimportant. The message must be duplicable, so that transmission does not cause a loss of information.

The transmission of messages via the network is time-consuming and the message may be lost on the way. For instance, when an object issues a synchronous invocation to another object, but the message is lost, the requesting object would be blocked forever. The basic action semantics does not give a solution to this problem. It is elaborated in other real-time profiles.