Dynamic FTP site and file locking

From: Rich Jordan (jordan_at_ccs4vms.com)
Date: 11/11/04

  • Next message: Chris Scheers: "Re: Need help with a PeeCee again." 
    Date: 11 Nov 2004 10:16:55 -0800

    We're going to be setting up an FTP site, hopefully on an OpenVMS
    Alpha system. The site will hold data files placed there by dozens of
    sources, updated every 20-30 minutes, via authenticated FTP sessions.
    The connection the data sources use is low bandwidth, and each
    transfer will take about 45-60 seconds; access by the downloading
    clients (using anonymous FTP) will be much faster. Older (VMS file)
    versions of the data files will be retained, but users coming in to
    get the files should normally only retrieve the most 'current' one.

    The system will be running VMS V7.3-2, TCPIP V5.4 ECO2, and _might_ be
    running Hunter's FTP server package (TBD).

    >From some testing with a network camera that FTPs files to a VMS FTP
    server, we've noted that if a request to d/l a file comes in during
    the period a data source is creating a new one, the downloading client
    will get an access error. Given the 45-60 second potential delay
    before a retry works, that isn't going to work for us.

    One obvious fix is to have the data sources FTP to a different
    directory or directory tree and use a process on the VMS system to
    watch for and move the data files to the outbound FTP directory; the
    interlock time would be reduced to a second or two per file. Or we
    could move the file into the anonymous FTP directory under a different
    name, then do a rename, which should reduce the interlock time to a
    fraction of a second (I think).

    That will work, but is there a better solution available?

    Thanks

    Rich
    CCS

  • Next message: Chris Scheers: "Re: Need help with a PeeCee again."

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