Subject: [XCON] Potential problem in the BFCP specification

From: Lorenzo Miniero <[email-masked]>
Date: Sun, 18 Mar 2007 10:23:37 +0100

Dear all,

by making some performance and robustness tests on our CONFIANCE platform, we
met what could be a potential problem in the BFCP specification.

A single FLOOR-REQUEST-INFORMATION can be quite big in size, considering it
contains a lot of optional text information (i.e. the STATUS-INFO in the
OVERALL-REQUEST-STATUS and in the FLOOR-REQUEST-STATUS subattributes, the
PARTICIPANT-PROVIDED-INFO and the text in REQUESTED-BY-INFORMATION and
BENEFICIARY-INFORMATION).
If many requests for the same floor are made, a FloorStatus message consequent
to a FloorQuery regarding that floor would contain A LOT of
FLOOR-REQUEST-INFORMATION, regarding all the requests that have been made for
the same floor and their current status. This means that the overall size of
the FloorStatus message can easily exceed the payload size limit in the common
header, that is only 16 bit.

Is this to be considered a potential problem in how the BFCP has ben specified
so far? Many requests for a same floor could be considered rare, if we take the
example of a floor assigned to a writable resource, as right to send audio
and/or video frames. But a floor could be assigned to a read-only resource we
want to moderate access to as well, and in this case many requests for the same
floor could be a quite more common situation.

In any case, in my opinion something should be thought to fix this, or at least
prevent it from happening. Extending the bits dedicated to the payload size
limit would be probably too invasive and not compliant with the current BFCP
RFC. A solution could be using one or more of the reserved bits to this case,
something like the Marker-Bit in RTP to allow more BFCP "packets" to compose a
single BFCP message, but this is only an idea.

What do you think about it?
We're looking forward to receiving your comments and feedback.

See you in Prague,
Lorenzo

-- 
Lorenzo Miniero, Junior Researcher
Dipartimento di Informatica e Sistemistica
Università degli Studi di Napoli "Federico II"
Via Claudio 21 -- 80125 Napoli (Italy)
Phone: +390817683821 - Fax: +390817683816
Email: [email-masked]

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