Re[2]: Too good to be true: Re: Asynchronous Exceptions in Java ...

[P.H.Welch@xxxxxxxxx]

Jim Wolffe wrote:

> Ian Page wrote: 
>
> > My guess is that this timing model is too tight for most of the systems
> > that you are interested in, but I think the basic observation is just
> > as true for you as it is for me: without the ability to express, reason
> > about and control the temporal behaviour of programs, you simply cannot
> > expect to build real-time systems routinely.
> 
> 
> 
> Right On!
> 
> This consideration is showing up in some areas that involve parallel 
> processing, the MPI/RT standard effort for example. I'm afraid, though, 
> that we are a long way from a generally useful methodology built on a 
> rigorous foundation. Can anyone offer some much-needed "magic" in this 
> area?
> 
> -------------------------------------------
> James Wolffe
> Sr Member Technical Staff
> Northrop Grumman Norden Systems

Take a look at Adrian Lawrence's two papers in the WoTUG-21 proceedings.
They offer an extended version of CSP to deal with hardware-software
codesign ... and other things.  Priorities (i.e. occam's PRI ALT and
PRI PAR) are included together with an outlined denotational semantics.
Whilst not explicitly dealing with time, it formalises what designers
need to capture about making choices between (time-critical) actions.

Here is the abstract to the second of these papers:

  HCSP is a variant of CSP adapted to capture the semantics of hardware 
  compilation, among other purposes. It extends CSP in several ways:
  it includes priority; events can be combined; new synchronization
  constructors are introduced; and state is explicitly modelled.
  Including state permits the treatment of shared memory as well as
  message passing systems. A possible denotational semantics is included
  here thus allowing proper treatment of such systems.  Although most
  of these extensions were motivated by the needs of hardware compilation,
  HCSP can be applied more widely including software and thus can form
  the foundation of a codesign language.

Peter Welch.

cc: adrian.lawrence@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx