FreeTDS Development Group

["Lowden, James K" <LowdenJK AT bernstein.com>]

> From: Paul Rensing [mailto:prensing AT cimetrics.com]
> Sent: February 24, 2003 10:23 AM
> 
> BTW, iBiblio's FTP server reports the RPM files as being of type
> "audio/x-pn-realaudio-plugin", presumably because of a clash of file
> extensions. Anything to be done about that?

FTP is primitive.  It cares about moving files, and cares very little about
their type.  You don't have to take my word for it; it's all there in RFC
959.  

Your FTP client sends a "LIST" command to the server.  The response,
according to the RFC, is "a listing" of the files.  No mention of type.  How
your client chooses to interpret that listing is its choice.  My experience
is, less is more.  (Really:

        $ ls -i `which less` `which more`
        5988 /usr/bin/less 5988 /usr/bin/more

>:))  Because any heuristic interpretation is bound to be wrong sooner of
later.  In your case, sooner.  

I hope you'll indulge a story, admittedly OT.  

Not too long ago, a vendor we use notified us that its ftp server would
switch from GMT to EST.  We puzzled over what that might mean, how it would
affect ftp MDTM ("modtime"), on which our batch processing relies.  Answer:
the MDTM command (it never became part of an accepted RFC, but it's widely
implemented) is specified to return the file's modification time and date in
GMT.  Our vendor's change didn't affect it at all.  

A few days later, my colleague complained that the vendor had gone
overboard.  He alleged the vendor, rather than going to GMT -5 had actually
switched (by accident, presumably) to GMT -10.  Sure enough, by comparing
what was on his screen to the output of MDTM, that was the case.  

But the server wasn't wrong.  Using another ftp client, it was obvious that
the LIST reponse was showing times in GMT -5.  Even Mozilla got it right, as
did IE 5.0.  The error was in IE 6 (IIRC): it apparently read the LIST
reponse, assumed the times were in GMT, subtracted 5 hours, and displayed
the result.  At best, they'd created a non-compliant client.  They certainly
went to a lot of effort to get the wrong answer.  

Because any heuristic interpretation is bound to be wrong sooner of
later....  

Thus endeth the lesson.  

--jkl


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