2.1.2 Content Negotiation (conneg)

NOTE: This charter is a snapshot of the 44th IETF Meeting in Minneapolis, Minnesota. It may now be out-of-date. Last Modified: 25-Jan-99


E. Hardie <hardie@equinix.com>

Applications Area Director(s):

Keith Moore <moore@cs.utk.edu>
Patrik Faltstrom <paf@swip.net>

Applications Area Advisor:

Keith Moore <moore@cs.utk.edu>


A. Mutz <andy_mutz@hp.com>
G. Klyne <GK@ACM.ORG>

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Description of Working Group:

A number of Internet application protocols need to indicate recipient capabilities, characteristics, and preferences when the resources they handle can vary in form. This working group will finalize registration procedures for distinguishing attributes which cause the media delivered to vary in form. The registration of these "media features" will provide a supplement to the MIME registration of media types and enable the development of a cross-protocol vocabulary for exchanging information on recipient capabilities, characteristics, and preferences. Since these distinguishing attributes commonly occur in related sets, this working group will also describe at least one method for referring to composite media feature sets. Experimental methods for using these features and feature sets within specific protocol contexts may be developed within this group or within the groups standardizing the relevant protocols.

The working group is aware of applications which desire to negotiate what content is delivered as well as the form in which it is delivered. As much as possible, the group will endeavor to create a framework for exchange sturdy enough to handle the later addition of this type of negotiation. It will not, however, address this need directly nor will it limit its design choices based on the possible later addition of this negotiation.

Goals and Milestones:

Feb 98


Submission of registration procedure draft as BCP

Feb 98


First draft of Requirements and frameworks document.

Feb 98


Submission of feature scenarios draft as Informational RFC

Mar 98


Revised draft of Requirements and frameworks document.

Mar 98


First draft of composite feature set draft.

May 98


Requirements and frameworks document to Information RFC

May 98


Revised feature set draft

Jul 98


Feature set draft to Informational RFC

Aug 98


Working Group Closes


Request For Comments:







Media Features for Display, Print, and Fax



Media Feature Tag Registration Procedure

Current Meeting Report

Minutes for CONNEG, 44th IETF
Reported by John Dykstra, edited by Ted Hardie

The group discussed the framework and terminology draft and decided that it would be useful to have it permanently available as an introduction and terminological reference, especially given the differences between X.500 definitions and CONNEG usage. After author review for currency, the document will be last called with a proposed status of Informational RFC.

The group then reviewed the current draft on the "type" content feature. There was no dissent on the need for a feature which expresses MIME content type, as this allows more comprehensive set construction for features which are specific to content types. The examples in the document need work; Bob Harriet and Larry Masinter agreed to provide examples based on specific devices.

The group discussed proposals for a "Content-feature" header. The discussion revealed that the group did not have enough the appropriate experience with the MIME specifications to be certain of the examples. External review of the examples and proposal will be sought by the chair.

The group then considered the two proposals for aggregating features. Both proposals allow for dramatically shortened feature expressions for complex cases; the set of IE4 capabilities was presented as one such common capability set that would benefit from these proposals. The URI proposal presented by Bill Newman allows for configuration at a variety of levels (original equipment manufacturer, OEM, user), where the hash proposal presented by Graham Klyne works best in situations where there is a finite number of well-known sets. Both have valuable points, but the group was unable to come to consensus on which approach is best. The group will continue to work toward a syntax which combines the advantages of both, possibly by using secondary references and possibly by presenting a hash-based URI. The group does believe that these differences are resolvable, but feels more time with the proposals is necessary to reach resolution.


None received.