Re: Distributed programming in heterogenous platforms

["Marin David Condic" <mcondic.auntie.spam@acm.org>]

The approach of building heterogeneous systems utilizing message passing in
one form or another is *extremely* popular in military systems. Often, its
just Mil-Std-1553 32 word messages for the sake of simplicity, but I've
personally worked on a number of projects dealing with radio communications
and rocket launching that have been based on message passing in various
forms. (Anybody ever heard of the TADIL-J catalog?) It has its strengths and
weaknesses. Obviously, once you define the message format with high
precision, any computer capable of connecting to the network can play and it
doesn't need any specific OS or programming language. The bad news is that
message catalogs can get quite large and complex and the protocols for
getting units talking to each other with the right timing and information
sometimes gets very convoluted. (O.K. First, I'll tell you to get started,
then you ask this other guy for this data. When you get it, you let me know
and start your power up cycle. In the mean time, I'll be talking to that
other guy over there and asking him to send you blah blah blah... :-)

Message passing systems are so common in military hardware that I'm suprised
that Ada didn't manage to get that quite right. It *almost* works to try to
build message catalogs with tagged records, but since you can't control the
representation sufficiently, you just can't use them to play in that
sandbox. The only way to do it is to resort to kludges that might just as
well have been written in C.

MDC
--
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Marin David Condic
I work for: http://www.belcan.com/
My project is: http://www.jast.mil/

Send Replies To: m c o n d i c @ a c m . o r g

    "I'd trade it all for just a little more"
        --  Charles Montgomery Burns, [4F10]
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Jim Rogers <jimmaureenrogers@worldnet.att.net> wrote in message
news:3D8F49D8.8000605@worldnet.att.net...
>
> This reference is a bit indirect, but the problem is the same.
>
> I worked on some robotic systems for the U.S. Army. The Army was
interested
> in developing an architecture allowing modules from various vendors,
> implemented using different languages and hardware, to work together.
> They developed the Joint Architecture for Unmanned Ground Systems (JAUGS).
>
> This is primarily a message based architecture. The messages are defined
> independent of any language, with a specified byte order. Messages can be
> separated into two broad classifications; periodic messages and events.
>
> The architecture is defined at http://www.jaugs.org/
>
> Jim Rogers
>