A new I/O model for the real-time specification for Java

The Real-Time Specification for Java (RTSJ) does not only provide features for realtime programming but also for direct device access. Both reading and writing to a device and reacting to external signals are supported. Unfortunately, the APIs provided have two major drawbacks: since a single class is used to access all types of I/O devices, it is hard to provide an efficient implementation; and there is no mechanism for the user to add new external signals. Alleviating this situation requires APIs that both provide the necessary extensibility and are still compatible with the existing APIs. This is achieved by using factories to provide type specific accessor classes and making happenings first class objects instead of just strings. The new design proposal also unifies happenings, timers, and POSIX signals.