I-D ACTION:draft-ietf-conneg-feature-sets-at-urls-00.txt
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A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Content Negotiation Working Group of the IETF.
Title : Syntax extensions for abbreviating media feature
sets with URLs
Author(s) : W. Newman
Filename : draft-ietf-conneg-feature-sets-at-urls-00.txt
Pages : 7
Date : 01-Mar-99
Other Internet Drafts from the CONNEG working group describe a
syntax[SYNTAX] and vocabulary[FEATURES] for negotiating media feature
sets which can be used for transmission of a message. For example, a
feature set may specify that full color output up to 800x600 pixels
is supported, or that output can have up to 300 dots per inch. These
feature sets can be arbitrarily complex, and typical feature set
expressions may be hundreds of bytes in length. It would be
relatively costly to transmit such long feature set expressions, and
this cost could be a significant obstacle to the use of the CONNEG
standard to negotiate capabilities for Internet transactions. The
problem is likely to particularly severe for low-bandwidth wireless
connections to the Internet.
This document describes an extension to the CONNEG syntax[SYNTAX]
which allows a feature set expression to be represented as an
absolute URL, which can then be looked up over another channel, which
is not necessarily the channel between the negotiating parties. By
using this extension, content negotiation between two parties can
proceed with a relatively small exchange of data over the channel
between them. Of course, the contents of the URL must still be found
through some channel. However, the channel used to find the contents
of the URL may have greater bandwidth than the channel between the
negotiating parties, and may further benefit from HTTP or other
caching mechanisms.
This extended syntax is only applicable when the receiver of the
feature set has the capability to fetch the contents of absolute
URLs. In contrast, the base, unextended syntax[SYNTAX] is applicable
to any transmission channel, without requiring any external resources
for the feature set transmitter or the feature set receiver.
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