--On Tuesday, 02 December, 2008 07:04 -0800 "Hallam-Baker,
Phillip" <pbaker@xxxxxxxxxxxx> wrote:
> One of the topics that came up in the architectural debate is
> that a few folk made statements of the form that application
> developers assume that applications only engage in bilateral
> communications. In fact one person went so far that
> applications developers are not aware of the range of
> applications protocols.
>
> But more generally, some appear to have voiced the opinion
> that the IETF transport area only serves the IETF applications
> area, not the Internet application developer community which
> is many, many times the size of the IETF.
>
> No examples were given of these non-application application
> protocols. So here is why there can only be bilateral
> communications at the application layer.
>...
Of course, there are a whole class of exceptions to this. There
are applications that perform minimal-effort notification or
database update functions that do not particularly care if the
notification gets through (i.e., can accept some data loss in
the process). I've worked on several such applications over the
years in which the consumer of the data needed only the most
recent values available and perhaps an indication of whether
recent data had been lost (easily accomplished with a simple
sequence number) or how recent the most recent available data
were (for which a time stamp is usually sufficient).
One set of examples for this involves remote sensors (sometimes
very remote, as in "in orbit") that are reporting on data that
are considered only statistically for other reasons.
Constructing, e.g., moving average models that can allow for
some missed data points is fairly straightforward and often
makes a lot more sense than trying to assure reliable
transmission or anything else that would require a bilateral
connection arrangement. While it is outside my personal
experience, I'd assume that sensors that deliver snapshots from
high-data-volume, high-data-rate experiments in physics would
have much the same properties, with the quantity and arrival
rate of the data overwhelming any possibility of bilateral
handshaking and the probability of some data loss being much
more acceptable than a lower sample rate.
In some cases, the transmitter at the sensor just broadcasts the
data on a known channel, with no information (including either
names or addresses) about who is going to receive it or how it
is going to be received. Certainly the receiver(s) need to
know the channel and the way in which the data are encoded, but
that doesn't involve the network in anything bilateral.
Or perhaps you are using "bilateral" in a way that I don't
understand.
john
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