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ACTION-112 follow-up: Conrad's vs current's proposal for Media Fragment Processing

From: RaphaŽl Troncy <Raphael.Troncy@cwi.nl>
Date: Wed, 02 Dec 2009 23:38:59 +0100
Message-ID: <4B16EC83.9070207@cwi.nl>
To: Conrad Parker <conrad@metadecks.org>
CC: Media Fragment <public-media-fragment@w3.org>
Hi Conrad,

Following the ACTION-112 thread on the mailing list [1], and today's 
telecon [2], I try to summarize the remaining questions and issues we 
have in order to get a clear picture and converge towards a common solution.

As you will read in the minutes of today's telecon, we distinguish two 
(ideal) cases (ignoring the fallback plans):
   - case 1: the URI fragment can be resolved directly with the server 
help and only one roundtrip (HTTP request / HTTP response) takes place
   - case 2: we introduce a hack so that the URI fragment can be cached 
in current proxies, two roundtrips take place

For the case 1, it seems that your proposal and the current's proposal 
are similar except that:
   . you introduce two new headers ('Fragment' and 'Content-Fragment')
   . your HTTP response is a 200 (and not a 206) and Yves argues that 
the  chances that a cached fragment will be reused and served from the 
cache is pretty low [3].

*Question:* could you please argue and explain what advantages the 
introduction of these two new headers bring?

For the case 2, both approaches require two round-trips:
   . Yves argues that we should use a 307 response code for the first 
roundtrip (instead of a 200)
   . The current proposal misses the information about the real time 
range it identifies when the bytes range request is issued. Should we 
simply fix it by adding 2 Range headers: one in bytes and one in e.g. 

*Question:* is the role of the new headers introduced by Conrad 
('Range-Refer' and 'Accept-Range-Refer') similar to the new headers 
introduced in the current proposal ('Range-Redirect' and 



[2] http://www.w3.org/2009/12/02-mediafrag-minutes.html

RaphaŽl Troncy
EURECOM, Multimedia Communications Department
2229, route des CrÍtes, 06560 Sophia Antipolis, France.
e-mail: raphael.troncy@eurecom.fr & raphael.troncy@gmail.com
Tel: +33 (0)4 - 9300 8242
Fax: +33 (0)4 - 9000 8200
Web: http://www.eurecom.fr/~troncy/
Received on Wednesday, 2 December 2009 22:39:50 UTC

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