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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Stream_Element_Array
Date: Fri, 16 Sep 2011 23:18:21 +0100
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Date: 2011-09-16T23:18:21+01:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:

> On Fri, 16 Sep 2011 18:20:09 +0100, Simon Wright wrote:
>
>> I certainly wouldn't expect any significant performance difference
>> between UDP and TCP with no-delay. I suppose what's significant for you
>> may not be for me. But very few system engineers IME appreciate the
>> difference; and by the time you've eliminated out-of-order UDP packets
>> you may have eaten the difference anyway.
>
> Exactly, whatever overhead TCP/IP might cause, it is one to pay anyway by
> adding safety to UDP (sequence numbers, acknowledging, resending lost
> packets, reordering packets etc).

We are of one mind here, indeed someone who thought that was a good idea
should also like the design of a project I worked on where heartbeat
(keep-alive) messages were not only application-generated but also sent
on a different socket from data messages. It took a lot of effort to
persuade TPTB that TCP/IP channels are bidirectional.

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.