Service vs. Port vs. SRV (following Eliot's presentation)

Folks,

This is in response to Eliot's presentation this morning, in the AppsArea and it 
is merely intended to solicit comment:

I have always understood the construct of Well-Known Ports as being a means of 
standardizing an efficient rendezvous mechanism, for clients to find servers. -- 
without quibbling about the terminology that might better cover use in 
peer-to-peer scenarios.

This creates a means of associating a "channel" to a protocol, in order to 
achieve a "service".

By way of example, SMTP and SUBMIT are (essentially) the same protocol, but they 
are different services (initial MUA-MSA posting, versus MSA/MTA or MTA-MTA or 
MTA/MDA relaying.)

In effect, Port 25 vs. Port 587 define the two different sservice.

SRV clearly serves as a more generalized and long-term mechanism for defining a 
service (and, gosh, doesn't that make the choice of the RR's name particularly 
nice?)

As Eliot notes, however, this builds a dependency on the DNS into the underlying 
construct of IP-to-IP rendezvous.  While most of the Internet use today already 
has that dependency as a pragmatic realtion, for other reasons, it is not built 
into the basics of Internet infrastructure as a formal requirement.

So changing our model to focus on SRV has some interesting implications.

Thoughts?

d/
--

-- 

   Dave Crocker
   Brandenburg InternetWorking
   bbiw.net