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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Stream_Element_Array
Date: Sat, 17 Sep 2011 10:18:52 +0200
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Date: 2011-09-17T10:18:52+02:00
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On Fri, 16 Sep 2011 23:18:21 +0100, Simon Wright wrote:

> On the other hand, if you have a tracker radar reporting target
> positions every 2 ms (I'm making that number up) it probably won't
> matter if you miss one or two reports, so as long as you take care not
> to use an out-of-order report UDP might not be inappropriate.

Theoretically yes, if you measuring a physical contiguous value, you can
live with losses. You cannot if you have discrete stuff: commands, impulses
etc.

But in reality even with physical values, if you have two, which are later
used in some sort of control loop, you have to ensure them coherent. You
could reconstruct missing points using time stamps, but then you would have
to add stamps, synchronize clocks etc. In the end something always emerges
on top of UDP.

Even for broadcasting purposes there exist stream-oriented protocols, which
are safe. We tested PGM, which showed quite decent latencies comparing to
TCP/IP + NO_DELAY.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de