Proposal: BOF on content-negotiation extensions to HTTP

From: Johan Hjelm (
Date: Mon, Jun 26 2000

Date: Mon, 26 Jun 2000 09:47:45 -0400 (EDT)
From: Johan Hjelm <>
Message-ID: <>
Subject: Proposal: BOF on content-negotiation extensions to HTTP

Dear All, 
We would like to propose a BOF on content-negotiation extensions to HTTP,
to be held at the 48th IETF, Pittsburgh, July 30 to August 4. 


During the past few years, there have been several proposals for
content-negation in HTTP. During the work in the CC/PP working group [1],
we have identified the need for extensions to the protocol to transport
the information structures describing the client capabilities and user
preferences for their use, which go beyond the accept headers currently
standardized in HTTP [2]. 

Efforts such as the ACAP protocol [3] assumes a separate protcol for
capability description, while CC/PP and Conneg [4] assumes a transmission
within the requesting protocol. This makes extensions to the
current HTTP headers necessary. 

Several proposals exist for this: The CC/PP exchange protocol based on
HTTP Extension Framework [5], the ICAP protocol [6], the Transparent
Content Negotiation in HTTP proposal (RFC 2295) [7], as well as the
general HTTP extension framework described in "An HTTP Extension
Framework" (RFC 2774). 

All these intend to solve the same general problem: The inclusion of an
extended parametrization in a request. We want to hold a Birds of a
Feather Session to discuss wether these could not use the same
mechanisms, and wether these mechanisms could be based on a common
standardization of an extended HTTP header set, as well as wether it would
be appropriate to charter a working group to take on the
specification work. It may also be appropriate to discuss extensions to
other protocols, but the popularity of HTTP and the number of existing
proposals makes us think this may have higher priority. 

The CC/PP Exchange Protocol has been implemented at least twice, one of
which is commercially available (the Ericsson WAP Application Server). 

In anticipation of the BOF, a mailing list has been set up at [9] to
facilitate discussion around this topic. 

Proposed Agenda 

Introduction and background - Johan Hjelm 

Presentations (15-20 minutes each): 

* Conneg work and protocols - Ted Hardie/Graham Klyne 

* CC/PP Exchange Protocol - Hidetaka Ohto 

* ICAP - ? 

* HTTP Extension Protocol - Henrik Frystyk Nielsen 


* What extensions are needed (if any)? 

* What are the requirements and use cases?   

* How should they be implemented? 


* Do we want to form a working group/is that appropriate? 

* Resulting work items 

Your comments and change suggestions to the agenda are welcome. 

Johan Hjelm, Chair, CC/PP Working Group 

Hidetaka Ohto, Author, CC/PP Exchange Protocol