RFC 114 (rfc114) - Page 2 of 17

File Transfer Protocol

RFC 114                 A FILE TRANSFER PROTOCOL           16 April 1971


   systems to determine the requirements and capabilities.  This paper
   is a "first cut" at a protocol that will allow users at any host on
   the network to use the file system of every cooperating host.

II.  Discussion

   A few definitions are in order before the discussion of the protocol.
   A file is an ordered set consisting of computer instructions and/or
   data.  A file can be of arbitrary length [3].  A named file is
   uniquely identified in a system by its file name and directory name.
   The directory name may be the name of a physical directory or it may
   be the name of a physical device.  An example of physical directory
   name is owner's project-programmer number and an example of physical
   device name is tape number.

   A file may or may not have access controls associated with it.  The
   access controls designate the users' access privileges.  In the
   absence of access controls, the files cannot be protected from
   accidental or unauthorized usage.

   A principal objective of the protocol is to promote the indirect use
   of computers on the network.  Therefore, the user or his program
   should have a simple and uniform interface to the file systems on the
   network and be shielded from the variations in file and storage
   systems of different host computers.  This is achieved by the
   existence of a standard protocol in each host.

   Criteria by which a user-level protocol may be judged were described
   by Mealy in RFC 91, as involving the notion of logical records,
   ability to access files without program modifications, and
   implementability.  I would add to these efficiency, extendibility,
   adaptability, and provision of error-recovery mechanisms.

   The attempt in this specification has been to enable the reliable
   transfer of network ASCII (7-bit ASCII in 8-bit field with leftmost
   bit zero) as well as "binary" data files with relative ease.  The use
   of other character codes, such as EBCDIC, and variously formatted
   data (decimal, octal, ASCII characters packed differently) is
   facilitated by inclusion of data type in descriptor headings.  An
   alternative mechanism for defining data is also available in the form
   of attributes in file headings.  The format control characters
   reserved for the syntax of this protocol have identical code
   representation in ASCII and EBCDIC.  (These character are SOH, STX,
   ETX, DC1, DC2, DC3, US, RS, GS, and FS.)







Bhushan