Re.: URA headsup

Leslie Daigle (
Fri, 2 Jun 95 12:20:25 -0400

Date: Fri, 2 Jun 95 12:20:25 -0400
From: Leslie Daigle <>
Message-Id: <>
Subject: Re.: URA headsup

[Note:  I am resending this message because the appeared
to be doing flakey things yesterday, and I have reason  to believe that
it never got through.  My apologies if this produces multiple copies
in your mailbox... -- LLD]

On the subject of URAs, Larry Masinter wrote:

> I'd like to hear from other WG members on this. I don't think that's
> an unreasonable request.

Yes, and I don't think its unreasonable to pull that request closer into the
spotlight (i.e., other than as a remark on the 3rd page of an e-mail
message addressing a different topic).

I have been asked to provide an update on URAs here in the mailing list, 
which is something else that falls into the category of reasonable requests.
Unfortunately(?!), we have been focussing our efforts on implementing 
proof-of-concept URAs and application, and haven't yet had a chance to
put our experiences/revised ideas into writing.  Since there still seems
to be some work to do in terms of communicating what we think the
basic premise of URAs, I think the best mechanism for presenting
updates is through a carefully considered revision of the old document --
and I will attempt to have such a document together and circulated as early as 
possible before the next IETF meeting.

In the meantime, as I said in my earlier message, we do have an alpha-test
version of an application that uses these prototype URAs.  I am willing
and interested to have a small group of URI WG people (say, up to 5)
play with this software and URAs for feedback to us and to the URI group
-- anyone who's interested and has either a Linux box or a Sun running
Sunos 4.1.3, drop me a line. 

I'm attaching a very brief reminder of what URAs are all about, but
first let me address the following:

Jon Knight wrote:

> Well seeing as Bunyip are doing the work anyway we might as well hear 
> what its all about and maybe make some useful input.  If they reckon its 
> more than "extended-URLs-with-lots-of-features" and can therefore do neat 
> things that can't be accompished easily or at all with the WG's existing 
> URI structures then maybe we should all sit up and take notice... :-)

Without  revisiting the entire URA draft paper (available as
draft-ietf-uri-ura-00.txt from all the usual places), let me say this
about why we believe URAs are not just "extended-URLs-with-lots-of-features":

URAs encapsulate activities into objects; the specification allows for URAs
to call on other URAs in the course of invocation.  For example, my
"mail subscriber" URA may call on a "NS-lookup" URA and then extract
a fully qualified domain name to complete its action, as well as calling
on an authentication URA to verify the permissibility of the activity.  A URL 
identifies a single resource --  at best it could point to a program that
carried out the same action as above, but that's not the same thing as
formally capturing the steps of the activity.



Uniform Resource Agents (URAs)

Uniform Resource Agents (URA's) are proposed as a means of specifying 
composite net-access tasks.  Tasks are described as "composite" if they 
require the construction and instantiation of one or more Uniform 
Resource Locators (URL's) or Uniform Resource Names (URN's),   and/or if 
they require transformation of information returned from instantiating 

A URA allows the encapsulation of network resource particulars, so that users 
(and user programs) can specify requests at a high level.  These are specified 
as objects, with a script component,  to provide a powerful yet manipulable 

The proposed objects are called "agents" because they are intended to 
perform some action on behalf of an invoker.  Nonetheless, there is a
fixed underlying model to the types of activity that can be undertaken
by a URA.  Namely, they combine content-specific data from the user with a set
of known Internet resources to carry out a high level activity.  The URA's 
perform the invoker's task by communicating with net resources through 
known protocols and with appropriate verification and authentication.


"Web space:                                            Leslie Daigle
   You go next door for a cup of sugar,      
   and wind up in a completely different universe."    Montreal, Canada
                   -- ThinkingCat