[AccessD] Ensuring FTP completion

John,

  Your going to quickly find that FTP is not fool proof.  Copying, renaming,
etc is not a valid way of checking if the file transmission is complete.  It
is possible to move/rename a partially copied file.  There is no locking.
Also, you going to find that files can be added/removed from the directory
while your working with it.

A couple of different techniques:

1. Zip the file before sending.  The zip/unzip builds in a check sum.  If
you unzip on the remote end and don't have the file, you'll get an error.

2. When working with a file, copy/rename to another directory that's
exclusive to you.

3. When downloading files, take a snapshot of the files that are there at
the start of processing, then work off the snapshot list.    Many FTP batch
jobs fail because they do a MGET followed by an MDEL.  In the meantime, new
files may have been uploaded.  Result, the newly uploaded file disappears.

 As an alternative, you can purchase AS2 software, which is basically
transactional messaging software for file transfers across the internet.
Most AS2 software supports both HTTP and FTP protocols.

Jim.

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com]On Behalf Of John Colby
Sent: Monday, January 16, 2006 3:16 PM
To: 'Access Developers discussion and problem solving'; Tech - Database
Advisors Inc.
Subject: [AccessD] Ensuring FTP completion


I am working on a system to FTP an MDB file to a web directory.  I need to
know that the file got there correctly.  Does anyone do this, and if so,
what tools do you use for the FTP up/down and how do you check to ensure
that the transfer completed?  I am going to need to do something like FTP up
under one name, then rename / delete the existing and rename the new to the
filename of the existing.  This has to be bulletproof though so I need to
know that it worked.

John W. Colby
www.ColbyConsulting.com


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