RFC 250

Some Thoughts on File Transfer 🎀

Okay so, this is RFC 250 from H. Brodie at UCLA-NMC (Computer Science), dated 7 October 71. It's filed under categories D5 and D7 🦋. It doesn't update anything and it doesn't obsolete anything, so it's a clean slate, bestie 💅. It also has NIC #7691.

Brodie is talking about the proposed Data Transfer Protocol (RFC #171) and File Transfer Protocol (RFC #172) 🧚. The team at UCLA-NMC thinks these could use some extra clarification and maybe a revision 🔥. People want to move bigger chunks of data than what usually goes over a regular TELNET connection, and the UCLA-NMC implementation attempts kept running into problems with these protocols 😭.

The first problem is probably the easiest to fix 💖. RFC #171 is kind of confused about the sequence number field in the descriptor and count transaction. The transaction header gives the sequence number 16 bits, but the sequence number field in the error codes transaction only gets 8 bits 🙈. UCLA-NMC thinks 8 bits is enough for a sequence number field ✨. If you shrink it to 8 bits and also delete the two NUL bytes from the descriptor and count header, that header drops to 48 bits. That's apparently just as easy to handle as the proposed 72 bit transaction header 💜.

The second problem is about the SEX time-sharing system 🌸. On that system, the "end" of a file (which would presumably be where an Append transaction starts) is almost completely context-defined. In other words, the program reading the file decides when it has hit the end 💀. So what "Append" actually means is kind of hazy. The proposed Mail Box Protocol uses the Append feature, so if you skip implementing this command in a File Transfer service, you lose a lot of usability 🍓.

Brodie's bottom line is that fixing these ambiguities should speed up implementation a lot, at least at UCLA-NMC 🌈⭐.

    [ This RFC was put into machine readable form for entry ]
    [ into the online RFC archives by BBN Corp. under the   ]
    [ direction of Alex McKenzie.                   12/96   ]