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Network Working Group                                   H. BrodieRequest for Comments #269                               UCLA-NMCNIC # 7817                                              6 December 71Categories:  File TransferUpdates:122,238,172Obsoletes:  NoneSome Experience with File TransferAt UCLA-NMC we have recently completed implementation of a program whichutilizes UCSB's storage capability via their Simple Minded File System(See RFC #122 by Jim White for a description of SMFS).  The use of theprogram is detailed inAppendix A.We learned a number of things in the implementation effort andsubsequent usage.  We think a number of these apply towards thedevelopment of a net- word-wide File Transfer Protocol, and we hope tostimulate further dis- cussion of these issues.  We discovered somethings in the UCSB protocol that we would like to see included in thenetwork-wide protocol, and we see some things that are in the currentlyproposed net protocol and are unfortunately absent from the UCSBprotocol.In the first category, is the UCSB file retrieval procedure.  The userspecifies among other things, a bit count of the number of bits to beretrieved in the current request.Successive RTF commands yield successive pieces of the file.  Portionsof the file can be spaced over by use of the SPF command.  We think thatthe ability of the user to specify the size of the "chunks" of the filehe is about to receive, along with the ability to access any part of thefile without having to get the entire file, is definitely an advantage.It makes the user programs easier to write since the problem of parsingthe input stream virtually disappears, as the user program knows exactlywhat to expect at all times.  In addition, the one request, one responsenature of the protocol avoids the problem of sending a request and thenreceiving pieces of data of unpredictable size at unknown intervals.The response to each RTF gives the comforting knowledge that "they'restill listening".  This leads us to believe that there is much to begained by the adoption of a one request, one response type of protocol.We might point out that for any significant file transfer, this does notseriously cut down on the overall data transfer rate, since a"defaulting" type of approach, as SMFS uses can be used to keep therequest messages very small.  We also have found the mandatory passwordscheme of UCSB quite easily used, and any server site, (i.e. a sitespecifically advertising file storage) can reasonably be expected, inour opinion, to require passwords (see also RFC #238 by R. Braden).                                                                [Page 1]

Network Working Group                                   H. BrodieRequest for Comments #269                               UCLA-NMCNIC #7817                                               6 December 71Almost immediately after starting to use SMFS we found a serious lack inone area.  There is no way for a user to ask "what files do I havethere?"  As a matter of fact, the author suspects that there are alreadyseveral files there which he has "forgotten" about!  It is reasonable,perhaps even necessary, for any server to supply a nicely formattedcharacter string describing the files stored there for this password, oruser, or whatever division is used.  The listing should also containother pertinent information, such as date created, size etc.In the meantime, UCSB is providing the SEX system with valuable "out-of-line on-line" storage, and we look forward to the development of awidely accepted file transfer protocol, implemented on a large number ofserver sites, hopefully equipped with low cost bulk storage.                                                                [Page 2]

SEX NotebookAppendix A              H. BrodieSection 23.29                                           3 December 71                                 FXFERFXFER is a re-entrant program written in Symbol which is used to send areceive file from UCSB, using their Simple Minded File System.  For thedescription of the Network interface to SMFS, see RFC #122 by Jim White.Files are stored there in a paged format identical to the paged formatthat the tape process uses: <header><data page><data page>...  Thus afile which Master lists as having n pages will take 2048 n bytes ofstorage at UCSB.  The user's sign-on initials are used as both theaccess and modification passwords, so that if a file is sent under onuser's sign-on, they can only be retrieved or deleted by him.CommandsPA - Increments "print All" counter.  Different settings of this     counter yield different levels of program trace output on     the console.NP - No print.  This sets the "Print All" counter to zero.DF FOO - This deletes the file "FOO" located at UCSB.PF FOO - This sends the file "FOO", pointed to by the user's root         directory, to UCSB.  Only read access is needed to "FOO".GF FOO - The file "FOO" located at UCSB is retrieved and put in the         user's root (with write access).  Note that it must have been         sent by the user to have the right password.RN FOO BAR - Rename the file "FOO" at UCSB to "BAR".  The same password             restrictions as with PF and GF apply.  (Not yet implemented)ST - Status.  Tells what program is doing and how much its done.X - Exit Program.If the system and/or UCSB is particularly slow, then UCSBFIL may type atime-out message.  At this point the user has the option of continuing,or exiting the program.  The message is self-explanatory, as are most ofthe program's messages.       [ This RFC was put into machine readable form for entry ]       [ into the online RFC archives by Nick Christenson 10/97]                                                                [Page 3]