Re: Vetting rules for UR* schemes

Roy T. Fielding (fielding@avron.ICS.UCI.EDU)
Thu, 30 Nov 1995 21:08:05 -0800

Subject: Re: Vetting rules for UR* schemes 
In-Reply-To: Your message of "Wed, 29 Nov 1995 11:03:00 +0100."
Date: Thu, 30 Nov 1995 21:08:05 -0800
From: "Roy T. Fielding" <fielding@avron.ICS.UCI.EDU>
Message-Id:  <>

> Re the statement
>>   <li> Are there ways of using pieces of the information inside it
>>        that implementations are supposed to get right?
> I was thinking of the case where someone comes up with a scheme like
> foobarlibrary:/stack=3/shelf=5/pos=3cm/librarian=jones/
> where the meaning would be "look in stack 3, shelf 5, 3 cm from the left,
> and if it isn't there, call for Jones".
> An application would then be expected to pick out the components
> /stack=3/shelf=5/pos=3cm/ and /librarian=jones/, and use each piece in
> one part of the foobarlibrary access method.
> (Note: The example was chosen for its silliness!)

Uh, yeah, but I get it now -- thanks.

> If something is designed to be broken into pieces, it should document
> what those pieces are, why it should be broken in this way, and why the
> breaks aren't where 1808 says that they usually should be.

That's much better.

> The language of the sentence is bad, but I don't want to make it much longer?
> does anyone have alternative language here?

Actually, I like the paragraph just above you -- nice and succinct, yet
tells people what they need to think about.

I've thought of one more:

   If the URI represents a hierarchy, the hierarchical parts should be
   represented top-down from left to right unless the opposite choice
   is required for historical reasons.  This allows a URI prefix to be
   used for various operations involving identifiers.

 ...Roy T. Fielding
    Department of Information & Computer Science    (
    University of California, Irvine, CA 92717-3425    fax:+1(714)824-4056