# Re: how to make progress on the URL document

Mark P. McCahill (mpm@boombox.micro.umn.edu)
Thu, 24 Mar 94 22:17:23 CST

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    Date: Thu, 24 Mar 94 22:17:23 CST

    Message-Id: <9403250417.AA22188@boombox.micro.umn.edu>

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

    To: dupuy@smarts.com, timbl@www0.cern.ch, uri@bunyip.com,

    Subject: Re: how to make progress on the URL document

In message <9403241750.AA22255@brainy.smarts.com> Alexander Dupuy writes:
> ...I think that there is some use to knowing that a particular URL
> represents a search rather than a document; it gives you some idea that
> this is more likely to return different information each time used than a
> document URL. In particular, I can imagine some caching schemes that might
> find this information useful
>
> Requiring ? as the separator for query URLs provides this information without
> requiring detailed understanding of the exact query syntax.

A caching scheme must have a way of fetching (and re-fetching) the resource.
This implies that there is a client around that knows the details of
the access method's protocol. In other words, you have a client that knows the
protocol, but you need a "?" convention because you don't know the protocol...
..I'm definately getting confused now... :-)

In some ways this sounds like a cheesy way of trying to get time-to-live or
cache timeout meta-information about the resource into the URLs.
URLs are supposed to give you enough information to retrieve the resource.
All the meta-information that is not required for retrieval of the resource
is supposed to be held elsewhere (in URCs or URNs or URSomethings). Given
the general agreement that non-required-for-retrieval meta-information does
not belong in URLs, this is a poor argument for requiring a "?" convention.

> > > 2. In a URL, if a "/" does not imply a hierarchy, it
> > > should be escaped. (This just affects gopher servers
> > > whose files contain "/" but aren't directory
> > > delimiters, like Mac servers). If you want the
> > > string to be 100% opaque, just specify that
> > > "/" is escaped.
> > >
> >
> > Once again, a URL consists of an access method and an opaque parameter
> > package for use by that access method. To know how to interpret the
> > opaque parameter package, the client writer needs to read the
> > section of the URL document that tells them how. If the access method
> > says that there is no heirarchy to be assumed, and you ignore this, then
> > you do so at your own risk.
>
> I have to agree with Tim that non-hierarchical / should be escaped. I know
> that partial/relative URLs are no longer in the requirements document;
> nonetheless, there are cases where relative references (not URLs) within
> collections of documents are very convenient...

Since partial/relative URLs aren't in the requirements document, arguments
about how nice it would be to have this non-required feature don't carry much
weight.

Mark P. McCahill

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

- Next message: Tim Berners-Lee: "Re: gopher URLs (was Re: how to make progress ...)"
- Previous message: Larry Masinter: "Re: URL: Outstanding issues"
- Maybe in reply to: Mark P. McCahill: "how to make progress on the URL document"
- Next in thread: Alexander Dupuy: "Re: how to make progress on the URL document"