Re: [ftpext] Fwd: New Version Notification for draft-bryan-ftp-range-06.txt
Anthony Bryan <anthonybryan@gmail.com> Fri, 29 June 2012 01:10 UTC
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Date: Thu, 28 Jun 2012 21:10:08 -0400
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From: Anthony Bryan <anthonybryan@gmail.com>
To: Tim Kosse <tim.kosse@filezilla-project.org>
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Subject: Re: [ftpext] Fwd: New Version Notification for draft-bryan-ftp-range-06.txt
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thanks, Tim! On Sun, Jun 17, 2012 at 5:07 AM, Tim Kosse <tim.kosse@filezilla-project.org> wrote: > On 2012-06-05 01:53, Anthony Bryan wrote: >> FYI, any comments? >> http://tools.ietf.org/html/draft-bryan-ftp-range > >> 3. octet Ranges in STREAM Mode > > The title of section 3 should probably start a capital letter. Yes. >> The server-PI SHOULD transfer the whole range from the start point to >> the end point with RETR if the end point is larger than the actual >> file. > > Seems unclear, in particular what to send between the end of the file > and the end point. I suppose you meant the following? > > The server-PI SHOULD transfer the whole range from the start point to > the end of the file with RETR if the end point is larger than the actual > file. Yes, changed. >> With STOR, however, the server must >> insert the data into the file named. The results are undefined if a >> client uses RANG to do other than restart to complete a transfer of a >> file that had previously failed to completely transfer. In >> particular, if the restart marker set with a RANG command is not at >> the end of the data currently stored at the server, as reported by >> the server, or if insufficient data are provided in a STOR that >> follows a RANG to extend the destination file to at least its >> previous size, then the effects are undefined. > > The requirement of the start point to be at the end of the file if used > with STOR is problematic. > > If a transfer is interrupted due to a network error, it can happen that > the for the client the transfer has failed already whereas the server > things it is still ongoing. If there is data still in-flight or > otherwise pending, the file size can change between the call to SIZE and > the subsequent RANG/STOR. Only workaround would be for the client to > wait an unspecified time before resuming until it can be reasonably sure > that there is no pending data still in-flight. > > I would change the semantics as follows: > > - The RANG start point must never exceed the file size > - If it is less than the file size, continue writing at that position in > the file, overwriting existing data between start-point and end-point. > - RANG must not cause files on the server to be truncated > - Implementation note: Some servers currently open the file with > O_APPEND if using STOR, they should not do this anymore. > > Apart from solving the timing issue, this change would also makes it > possible to selectively modify parts of a file on the server. that sounds good to me and like a nice bonus. what do others think? -- (( Anthony Bryan ... Metalink [ http://www.metalinker.org ] )) Easier, More Reliable, Self Healing Downloads
- [ftpext] Fwd: New Version Notification for draft-… Anthony Bryan
- Re: [ftpext] Fwd: New Version Notification for dr… Tim Kosse
- Re: [ftpext] Fwd: New Version Notification for dr… Anthony Bryan