XCON Working Group M.
Brunner
Internet-Draft
NEC
Expires: April 18, 2004 October 19,
2003
Issues and Requirements in Floor Control
draft-brunner-xcon-fc-00
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Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This documents lists issues and requierements for floor control in
conferencing applications. It is meant in addition to the existing
requirements draft "raft-koskelainen". It basically proposes to do
floor
control in a policy less way. Meaning that the policies are
built into
the floor dcontrol server, but not part of the protocol.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . .
. . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . .
. . . . . . . . 4
3. Issues . . . . . . . . . . . . . . . . . . . . . .
. . . . . . 5
3.1 Scope of the floor . . . . . . . . . . . . . . . . . .
. . . . 5
3.2 Number of users concurrently holding the floor . . . . . .
. . 5
3.3 Floor Control Policies . . . . . . . . . . . . . . . . . . . .
5
3.4 Explicite versus implicite floor passing . . . . . . . . . . . 5
3.5 Floor passing trigger . . . . . . . . . . . . . . . . . . . . 6
3.6 Activity awareness . . . . . . . . . . . . . . . . . . . . . . 6
4.
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7
Informative References . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . 8
Intellectual Property and Copyright Statements . . . . . . . .
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1. Introduction
Floor control is a
mechnism used to deal with concurrecy in
distributed systems. So it
basically deals with the question who is
allowed to generate input or
change/write to a resource.
In the context of conferencing systems floor
control has two
different goals. First it is about who is allowed to
"speak" by
sending data input into the conference, so has to do with
access
control. Second, there are some applications which also require
the
ordering of input in order to work correctly (single
input/sequential
input applications). In the laterc ase floor control can
help to
create correctly functioning
applications.
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2. Terminology
floor
- the right to generate some input.
floor control - determines at any
given point in time, which entity
is allowed to provide input, where
entity could mean a user or an
automated application.
floor holder -
user currently allowed to provide input.
floor control mechanisms - the
low-level protocol handling the floor
control.
floor control policy -
the rules for a certain operation of floor
control.
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3. Issues
3.1 Scope of
the floor
The floor can be assigned to various entities. E.g., a floor
for a
single session, an application, a conference. We assume an
application can have several session, and a conference can have
several
applications. The floor can be bound to any of these
entities. There is
naturally a dependency on what application the
floor control mechnisms is
used for.
3.2 Number of users concurrently holding the floor
It is
possible that several users concurrently hold the floor. For
example, in
the case of audio input to the conference, it is then
mixed together.
Other applications such as shared workspaces/
application sharing might
have a problem with concurrent input.
3.3 Floor Control Policies
Floor
control policies define the way how the floor is passed around.
Here are
some examples of floor passing:
- ring passing: the current floor holder
must explicitly release the
flooer before anyone else can axquire it.
- Preemptive: any user can grab the floor at any time
- Timeouts: a user
looses the floor after a period of inactivity or
after a given time
holding it.
- Moderated: a designated user has control over passing the
floor.
- IETF meetings: mostly moderated with queueing of floor
requests.
3.4 Explicite versus implicite floor passing
Explicite floor
passing requieres an explicit action of a user
passing the floor.
Implicit floor passing automatically gives the
floor to a user as soon as
he generates input. Implicit floor passing
together with a preemtive
policy corresponds actually to the case of
having no floor control at
all. For conversations this means also
that a social protocl and etiques
is needed.
Implicit floor passing is much easier from users point of
view, since
no expicit action is requiered. Since the floor might be
passed
implicitly there need to be a group of users eligible to get the
floor, where others might not get the floor implicitly. In the
IETF
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meeting example, the floor can implicitly pass between all
the people
having a microphone, where others waiting in the queue are
not
eligable for getting the floor implicitly.
3.5 Floor passing
trigger
In implicit floor passing there needs to be a trigger to pass
the
floor automatically. Specifically in multi-application/session
conference the trigger can be chosen freely. E.g., the person start
speaking also get the floor for the shared whiteboard etc.
3.6 Activity
awareness
In conferencing scenarios users normally want to be aware what
is
going only. So for exmple they might want to know who currently has
the floor etc.
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4. Requirements
MUST allow for various scopes
MUST have single and concurrent floor
holders
MUST be independent of a particular floor control policy.
The
policy should be part of a particular implementation, not of the
mechnisms itself.
MUST be able to restrict the group of users
eligible for implicit
floor passing.
MUST provide means for
distributed floor information (e.g.,
current floor holder to other
participants
SHOULD allow for transporting trigger filter
information. What
triggers the implicite floor control
change
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Informative References
[1]
Koskelainen, P., "Requirements for Floor Control", DRAFT
draft-koskelainen-xcon-floor-control-req-00.txt, June 2003.
Author's
Address
Marcus Brunner
Network Laboratories, NEC Europe Ltd.
Kurfuersten-Anlage 36
Heidelberg 69115
Germany
Phone: +49 (0)
6221 905 11 29
EMail:
brunner@ccrle.nec.de
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