RFC 451 (rfc451) - Page 3 of 3

Tentative proposal for a Unified User Level Protocol

RFC 451           Unified User Level Protocol Proposal     February 1973


Although this is a tentative proposal and not meant to be a detailed
design spec, one elaboration suggests itself which might make the
general idea more attractive: For ease of implementation on some
systems, it would probably be a good idea to define additional TCC's for
"Begin User Protocol".  That is, the user side starts the FTP by sending
the "Begin FTP" Telnet Control Code, waits for the Server to send either
the same code or the one for "Unimplemented Generic Function", and then
proceeds (or not) to send STOR's and RETR's and the like.  (It could
also follow the "I will"/"I won't" style discipline of RFC 435 if we
like.) Probably each line is preceded by the Network Generic Function
TCC so that systems which don't pass input off to some other process can
still distinguish between input to the system command processor and
input to the procedure(s) which perform(s) the protocol in question,
although perhaps it would be preferable to have an "End Protocol" TCC.

Now, I'm the first to admit that what makes sense to me, on my system,
may not make sense on somebody else's.  But it does seem plausible to me
that the unified user level protocol I've sketched here ought to be no
harder to implement than the multiple contact socket (MCS) ICP is.  And
the advantages of the UULP over the MCS ICP in terms of ease of
extension and (at least in my mind, if not in this paper) clarity make
it seem worthwhile to consider further.  So rather than try to refine it
here, let me simply ask for comments both on the general notion and on
the necessary iteration of the design from sketch to spec.  (The Multics
scenario in ICCC booklet shows how to get "mail" to me, for those who
don't feel like RFCing or phoning.)










       [ This RFC was put into machine readable form for entry ]
       [ into the online RFC archives by Alex McKenzie with    ]
       [ support from GTE, formerly BBN Corp.             9/99 ]












Padlipsky