Subject: Re: associating constant feature set

From: Bill Newman <[email-masked]>
Date: Wed, 20 Jan 1999 09:30:11 -0800 (PST)

Franklin wrote

> I thought that "delegation" referred to a mechanism for asking one or more
> third parties to provide partial or complete profile information. Partial
> profile information from multiple sources could be aggragated in some way
> to provide a complete profile. Such a third party might be a cache or proxy
> or some other server not normally part of the communication channel. In
> the CC/PP paper there was a notion of "indirect references" which were
> URLs that named profiles with default values that could be superseded by
> a user agent.

I started calling it "delegation" just because I was getting tangled
up in in sentences where "delegate" works fine as an active verb but
"refer indirectly" gets complicated or ambiguous. I didn't intend 
"delegate" to have any special technical meaning.

I'm not sure whether what you wrote above shows that you prefer to
attach a special technical meaning to "indirect references", tying
them up with idea of an algebra which can handle defaults. I myself
would prefer to separate the idea of indirect references (which is in
my mind the same as what I've been calling delegation) from the idea
of dealing with defaults.

Indirect references (without defaults) could be useful for many mobile
devices. Defaults (without indirect references) could be useful to
solve the font problem. And the two features work well together, too:
defaults increase the power of indirect references.

I think both problems are important -- I actually worry more about
defaults and the font problem than I do about indirect references.
But I also think indirect references are easier to solve. Extending
the algebra to allow just the right beyond-first-order-logic things to
be done, and doing it in a flexible, easy-to-understand,
not-too-hard-to-implement way is subtler and probably harder.

  Bill Newman
  [email-masked]

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From: Graham Klyne <[email-masked]>
Date: Thu, 21 Jan 1999 12:34:54 +0000

At 09:30 20/01/99 -0800, Bill Newman wrote:
>[...] I myself

Good principle, I think.

>defaults increase the power of indirect references.

... and that's a good example why

>not-too-hard-to-implement way is subtler and probably harder.

I suspect these are both difficult problems, with different kinds of subtlety.

IMO, the "default" problem is relatively self-contained so a solution can
be developed and tested in relative isolation.

OTOH, I se the "indirect reference" problem as something that (potentially)
impacts/interacts with the behaviour of other protocols (including transfer
protocols), and that begs questions like:  how to maximize othogonality
between representation and mechanism?;  how to ensure the solution is
scalable for tjhe Internet?;  etc.

To recap, I think the separation of defaults and indirect references is an
important insight -- thanks for that!

#g

------------
Graham Klyne
([email-masked])