RFC 486 (rfc486) - Page 1 of 2

Data transfer revisited

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Network Working Group                           Bob Bressler
RFC #486                                        BBN
NIC #15064                                      20 March 1973


                        Data Transfer Revisited


    A lot of work has recently gone into the development and refinement
of both the RJE and FTP protocols.  Stepping back from the details and
small issues, we can describe the two protocols as 1) a control
connection over which commands are passed, and 2) a data connection over
which uninterpreted (by the server process) data is passed.  Both
protocols deal with the concept of identifying oneself to the server,
setting up parameters, and transferring some data.

    New ideas and concepts, such as the "hot card reader", have been
introduced into one protocol or the other, but these concepts are
generally applicable to both.  In addition, a great deal of effort was
made to make the structures of the two protocols be as similar as
possible.

    This discussion is, of course, leading to the suggestion that we
stop considering these as two separate protocols, and merge them into a
single unit - perhaps resurrecting the name of "data transfer".

    Several advantages besides simplicity are gained by this.  Sites
need only build one server program - given that they can always respond
with "command not implemented".  This will also prevent the RJE users
and servers from having to start up a (possibly) separate FTP user and
server - saving the resulting doubling of programs and Telnet
connections.

    The further advantage of insuring that new ideas and concepts will
be shared by all users and servers will also be realized.  A RJE user
will be able to transfer his deck of cards (file) to storage on another
machine's file system using the "hot card reader" previously defined
only in the RJE protocol.

    The command set of the combined protocol would now consist of
several sets of command types.  These sets include:

    a.  general system commands (e.g., USER, HELP)

    b.  parameter settings (e.g., TYPE, STRU)

    c.  data control (e.g., ABORT, REIN)




Bressler
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