URLs should contain types

Larry Masinter (masinter@parc.xerox.com)
Fri, 21 May 1993 20:19:33 PDT

To: uri@bunyip.com
Subject: URLs should contain types
From: Larry Masinter <masinter@parc.xerox.com>
Message-Id: <93May21.201947pdt.168962@nebula.parc.xerox.com>
Date: Fri, 21 May 1993 20:19:33 PDT

I don't know how successful I will be at introducing this at this
time, since people are happy to 'go with' the current URL
specification, but I think that as time goes on, we'll be unhappy if
we don't allow URLs to explicitly name what kind of resource it
locates. Most of this typing is implicit: you know that telnet:foo.com
doesn't point to a color picture, and that ftp://host.edu/pub/test.gif
is probably an image.

Typing should be as specific or as general as you like. Thus, you
could say ftp://host.edu/pub/test.gif::image or leave the type out,
and hope for the best, or include
ftp://host/pub/test.gif::image/gif/89a if you want to include a
specific image format.

On the other hand, URNs *shouldn't* be typed; that part of the
name->location mapping can actually be name->(location,format).

Of course, mime types, suitably extended, could be used for URN types;
certainly there's no point in creating another registry.

I'll indulge in wishful thinking and hope that I don't have to argue
too vehemently for this, and just wait for the objections to roll in.