A Comparison of the Asynchronous Transfer of Control Features in Ada and the Real-Time Specification for Java

Asynchronous Transfer of Control ("ATC") is a transfer of control within a thread, triggered not by the thread itself but rather from some external source such as another thread or an interrupt handler. Such functionality is useful for several purposes; e.g. expressing common idioms such as timeouts and thread termination, and reducing the latency for responses to events. However, ATC presents significant issues methodologically, semantically, and implementationally. This paper describes the approaches to ATC taken by Ada and the Real-Time Specification for Java, and compares them with respect to programming style, expressive power, and efficiency.