URI/URL [Was Re: [LINK] Limit Email Size ...]

[Glen Turner]

On Fri, 2007-10-12 at 11:06 +1000, Roger Clarke wrote:
> At 10:41 +1000 12/10/07, Marghanita da Cruz wrote:
> >From a security perspective it would be ideal if all attachments 
> >were replace by a URL or URI (can anyone explain the difference to 
> >me?)

The original idea was

 Universal Resource Location
   where to find something
   eg: http://www.example.edu.au/books/isbn12345678.html

 Universal Resource Name
   what to find
   eg: isbn:123456789

 Uniform Resource Identifier
   either a URL or a URN

The assumption being that URNs are more stable over time than
URLs.

URIs were designed to be a definition that allows applications to parse
a string like http://www.exmaple.edu.au/example.html, isbn:123456789,
gopher://gopher.example.edu.au/ or telnet:myhost.example.edu.au into its
parts without knowing anything about HTML, ISBNs, Gopher or Telnet.  This
allows programs like Firefox to pass a URI to a proxy server, and the proxy
server can implement the scheme (isbn, gopher, telnet, etc) required by the
URI.

It's fair to say that the hopes that URNs would become the
dominant way of finding information are pretty much near-dead,
unless you regard Google as a URN-to-URL converter.