Some Experience with File Transfer (RFC0269)
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2019-Feb-13
Internet Society Requests For Comment (RFCs)
Network Working Group H. Brodie Request for Comments #269 UCLA-NMC NIC # 7817 6 December 71 Categories: File Transfer Updates: 122, 238, 172 Obsoletes: None
Some Experience with File Transfer
At UCLA-NMC we have recently completed implementation of a program which utilizes UCSB’s storage capability via their Simple Minded File System (See RFC #122 by Jim White for a description of SMFS). The use of the program is detailed in Appendix A.
We learned a number of things in the implementation effort and subsequent usage. We think a number of these apply towards the development of a net- word-wide File Transfer Protocol, and we hope to stimulate further dis- cussion of these issues. We discovered some things in the UCSB protocol that we would like to see included in the network-wide protocol, and we see some things that are in the currently proposed net protocol and are unfortunately absent from the UCSB protocol.
In the first category, is the UCSB file retrieval procedure. The user specifies among other things, a bit count of the number of bits to be retrieved in the current request.
Successive RTF commands yield successive pieces of the file. Portions of the file can be spaced over by use of the SPF command. We think that the ability of the user to specify the size of the "chunks" of the file he is about to receive, along with the ability to access any part of the file without having to get the entire file, is definitely an advantage. It makes the user programs easier to write since the problem of parsing the input stream virtually disappears, as the user program knows exactly what to expect at all times. In addition, the one request, one response nature of the protocol avoids the problem of sending a request and then receiving pieces of data of unpredictable size at unknown intervals. The response to each RTF gives the comforting knowledge that "they’re still listening". This leads us to believe that there is much to be gained by the adoption of a one request, one response type of protocol. We might point out that for any significant file transfer, this does not seriously cut down on the overall data transfer rate, since a "defaulting" type of approach, as SMFS uses can be used to keep the request messages very small. We also have found the mandatory password scheme of UCSB quite easily used, and any server site, (i.e. a site specifically advertising file storage) can reasonably be expected, in our opinion, to require passwords (see also RFC #238 by R. Braden).
Network Working Group H. Brodie Request for Comments #269 UCLA-NMC NIC #7817 6 December 71
Almost immediately after starting to use SMFS we found a serious lack in one area. There is no way for a user to ask "what files do I have there?" As a matter of fact, the author suspects that there are already several files there which he has "forgotten" about! It is reasonable, perhaps even necessary, for any server to supply a nicely formatted character string describing the files stored...