IPP Mail Archive: Re: IPP> MOD/PRO - simple proposal for providing dictionary-like capability

Re: IPP> MOD/PRO - simple proposal for providing dictionary-like capability

James Walker (walker@dazel.com)
Wed, 25 Mar 1998 15:16:12 -0600

Tom Hastings wrote:
>
> For the IPP telecon, Wed, 3/25:
>
> Roger, Bob, and I have been working on various dictionary proposals.
>
> ...
>
> Briefly, the scheme isn't really a dictionary at all (previous
> versions were). Other earlier versions were adding a new addressing
> mechanism for attributes in dictionaries.
>
> This proposal adds no new addressing mechanisms,
> but justs add a new out-of-band value to encode the new Model attribute
> syntax of 1setOf 1setOf (doubly nested values). Instead, we use the
> idea of attributes with parallel values, like we already have for
> "printer-uri-supported" and "uri-security-supported".

As discussed in the telecon today, I think that the parallel attribute
idea is a bad one... it does not scale well, it is difficult for users
to understand and get right, it is error-prone, etc. Our experience
from the implementation of parallel attributes in DPA has not been a
good one. All in all, I believe that data structures are a good idea,
but trying to describe data structures using parallel attributes does
not work.

> ...
>
> I've left the rejected example that uses the 'dictionary' attribute syntax
> in the document. I've also listed the alternatives that we considered
> and the reasons for rejecting them.
>
> ...

I simply do not understand why the original concept of a dictionary
value tag (with its associated value length) would not work well.
This is the example that is shown in Tom's document.

...walker

--
Jim Walker <walker@dazel.com>
System Architect/DAZEL Wizard
DAZEL Corporation, Austin, TX