Prioritised Dynamic Communicating and Mobile Processes

Continuing research on language design, compilation and kernel support for highly dynamic concurrent reactive systems is reported. The work extends the occam multiprocessing language, which is both sufficiently small to allow for easy experimentation and sufficiently powerful to yield results that are directly applicable to a wide range of industrial and commercial practice. Classical occam was designed for embedded systems and enforced a number of constraints, such as statically predetermined memory allocation and concurrency limits, that were relevant to that generation of application and hardware technology. This work removes most of these constraints and introduces a number of new facilities: explicit channel ends, channel bundles, mobile ends of channels and bundles, dynamic process creation, the extended rendezvous and process priorities. These significantly broaden occam's field of application and raise the level of concurrent system design directly supported. Concurrency overheads have been driven ever downwards, for example synchronising channel communication is now around 100 nanoseconds on an 800 MHz P3, and most operations have unit time cost. Finally, a proposal for secure mobile processes is made.