2.1.2 Content Negotiation (conneg)

NOTE: This charter is a snapshot of the 45th IETF Meeting in Oslo, Norway. It may now be out-of-date. Last Modified: 07-Jun-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



A Syntax for Describing Media Feature Sets

Current Meeting Report

Minutes for CONNEG, 45th IETF
Reported by Ari Bixhorn, edited by Ted Hardie
July 13, 1999, 1300

The group began with a discussion of the spam received by the wg mailing list. This is derived from some harvesting of web references to the list by spammers. The group decided not to change wg mailing lists because of short projected time to shut down, but will keep this tactic in mind should the group need to stay open past the current milestones

The group agreed with the current plan to put forward the syntax error draft for proposed standard and to list the current RFC as updated by that standard; this would allow the ITU to continue to reference the same RFC number. James Rafferty of the FAX working group will forward a copy to the ITU once the IESG has considered it.

The group hummed the submission of the framework draft as an informational guideline to the CONNEG framework.

The chair solicited MIME-savvy volunteers to review the two MIME-related drafts.

The eager volunteers are:
- Stuart McCree
- Larry Masinter
- Jacob Palme
- Ned Freed
- Uri Venchenko
- Lloyd McIntyre
- Maurizio Codogno

Larry Masinter asked the group to consider documenting an accept header to parallel the Content-features response header; this draft would be specific to those aspects of MIME supported by HTTP. Lisa Lippert and Larry Masinter will coordinate this after the referencing mechanism for composite capabilities is determined; this might be an individual submission by them.

As part of the discussion of the MIME-related drafts, Larry Masinter proposed the need for a generic parameter method for the CONNEG framework. Discussion among Larry Masinter, Graham Klyne, and Ted Hardie indicated that there were several benefits and challenges to this effort. The language in the current draft will be left discouraging the use of parameters within MIME types referenced by the "Type" feature. This will allow the development of a later parameter tree or similar mechanism.

The group then discussed the feature hash draft. The group agreed that there must be a compact way to reference composite feature capabilities for the conneg framework to take real root in protocols. After discussion of the history of the current draft and its two current proposals for allowing compact references (hashes and URLS) and the role of the where clause.

After discussion, the group hummed on keeping the hash-based mechanism and allowing a URL to be referenced in a where clause related to the hash. Consensus on eliminating the directly URL based mechanism was not reached, however. Lloyd McIntyre, James Gietz, James Rafferty, John Richardson and Ted Hardie spoke in favor of eliminating it; Larry Masinter and Graham Klyne both favor retaining it, however, and argue that we have not gotten enough input from the community of developers and users to decide to eliminate it. Larry Masinter argued that hashing might be valid for FAX and similar applications, but not effective for web publishing.

The chair asked the authors to update the draft with usage cases for the different applications. He also solicited reviewers for the document. The eager volunteers were:
- Lloyd McIntyre
- James Rafferty
- James Gietz
- Maurizio Codogno

Discussion of milestones and closing the group revolved around both the implementation experience coming up in FAX and the need to coordinate with the CCPP group emerging in the W3C.

The AD present (Patrik Falstrom) agreed that there may be additional work, but stated that the group would need to be re-chartered or a new working group created. After a review of the current status of all charter drafts with the AD, the meeting ended.


None received.