# Re: URLs -- the ftp case

Mark P. McCahill (mpm@boombox.micro.umn.edu)
Thu, 28 Oct 93 09:10:41 CDT

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    Date: Thu, 28 Oct 93 09:10:41 CDT

    Message-Id: <9310281410.AA03308@boombox.micro.umn.edu>

    From: "Mark P. McCahill" <mpm@boombox.micro.umn.edu>

    To: fred.swartz@umich.edu, uri@bunyip.com

    Subject: Re: URLs -- the ftp case

In message <9310271954.AA04238@merit.edu> "Fred Swartz" writes:
> In the case of ftp, the URL as specified does NOT allow the retrieval
> of files since the text/binary mode can not be determined. This
> difference may not be important for those of you who use only one kind
> of system (eg Unix), but the representation of text files differs on
> Unix, DOS, and the Macintosh. The transfer mode must be known to make
> intersystem transfers work correctly.
>

When I read the part of the URL spec that talks about ftp,
it makes me think that URL actualy stands for Unix Resource Locator.
If you make a lot of assumptions and everything is on Unix it
might work. For ftp servers run off other systems I don't understand
how to make it work.

> There is a certain air of unreality in the ftp URL description
> in that it reads as though everything is fine, and only in the
> last paragraph brings up the fact that the URL as specified really
> doesn't work. As a practical matter it does mention that you can
> make guesses by looking at the file name and the data, but you
> will never know for sure.
>
> Instead of giving the false impression that URLs work for ftp, perhaps
> the mode, as with Gopher, could be added.

yes. a simple flag that tells you transfer mode (text or binary) and
if the path points to a directory or a document would make this usable.
And you wouldn't have to try to interpret paths based on the assumption
that everything in the world is Unix.

> This is a very distant
> cousin of "type" in that it really indicates the transfer mode, not
> the object type. In other words, postscript, rtf, ... files are
> all transfered in text mode, even though you may think of them as
> having different types.
>
> One way to indicate these two transfer modes might be to have alternate
> protocol identifiers: ftpt and ftpb (for text and binary).
>

You would also need ftpd (for URLs that point at directories), if you were
going to take this approach.

Mark P. McCahill

gopherspace engineer/University of Minnesota
mpm@boombox.micro.umn.edu
612 625 1300 (voice) 612 625 6817 (fax)

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