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From: "Tony Matthews" <tony.matthews@SpamJam.gecm.com>
Subject: Re: Sequential_IO Data Portability
Date: 2000/02/01
Message-ID: <38972823$1@pull.gecm.com>#1/1
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 <3895E8B2.AD802742@SpamJam.gecm.com> <3896E408.7790@nospam.com.tj>
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Newsgroups: comp.lang.ada
Date: 2000-02-01T00:00:00+00:00
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Andy <andy@nospam.com.tj> wrote in message
news:3896E408.7790@nospam.com.tj...
> > Nick Roberts wrote:
>
> The project I work on does not share files, but we do share binary data
> (via messages) between
> a number of DEC Alpha platforms (using Rational Apex) and VME 68k
> platforms (using a Greenhills
> compiler). In the end we deceided to bite the bullet and rep spec all
> the messages (and closure
> of the all the types used in these messages).
>
> To this end we have developed a tool (written in shell scripts & Perl)
> to auto generate the rep
> specs. The rep specs are such that they are evaluated at compile time.
> Thus if a low level type
> changes, say from scalar to a physically larger/smaller scalar, or to a
> composite type, then the
> rep specs of the types dependent upon this type are automatically
> adjusted at compile time (by
> both compilers).
>
> While I cannot provide the scripts or the Perl (they are designed to
> work within an Apex
> environment anyway) I could provide more info on the compile time
> arithmetic we perform in
> order to generate the rep specs if required.
>
> (we also have to perform endian conversions, but that's another story).
>
> ___________________________________________
>
> Andy Starritt
> ___________________________________________


I didn't want to scare anyone away with too much detail, but we also pass
binary messages via LAN between
the sub-systems for the purpose of health monitoring, request/response, data
transfer etc, so the consistent binary
representation provided between sub-systems by having the same Ada compiler
is something we rely on at present,
and would be a great loss to us.

We also use Rational Apex as our development environment (Apex NT 3.0.2b
with a Solaris shadow server in fact), so
your approach is certainly a promising alternative.

However, I'm still hoping that I can avoid having to do that, use a single
compiler across both platforms, and leave it
all to the compiler!

If you have the time to e-mail me with further details, I will follow this
up with you.

Thanks.

Tony M.