Re: 4 beginner's questions on the PL Ada

[Emanuel Berg <embe8573@student.uu.se>]

Simon Clubley <clubley@remove_me.eisner.decus.org-Earth.UFP> writes:

> Would you rather implement, say, a communications protocol by
> looking at a existing implementation only, or would you rather
> work from a design specification which will include the
> background and overview as well as explain the reason for why
> certain things are done in the way they are?

Again, those CS models - if your task is to implement one of those
- of course you need to study the model/specification. Naturally,
in all those cases, it is as you describe.

My layman's attempt to define what constitutes a protocol would
be:

1. The message format, including its OH fields and what they
carry. For example, in a CAN bus message, there are 11 bits of
message ID (which is also used as priority), and after that, ...

2. How the communication should be conducted. For example, the
dance steps of the TCP/IP, with ack's back and forth: how it is
done, and what it means, and when, and in what order, ...

For 1., I'd use a data structure, and for 2., ordinary control flow
logic, perhaps in a PL with IPC support (Ada tasks with entry -
accept, perhaps? but I'm new at Ada).

All this is just examples, but it is clear that: *no*, you can't,
and shouldn't, write a single line of code until you have the
specification, and have studied it in detail.

Still, while interesting, it is not really what I tried to, um,
"communicate".

-- 
Emanuel Berg - programmer (hire me! CV below)
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