Subject: [XCON] Authorization in conference policy

From: Aki Niemi <[email-masked]>
Date: Wed, 28 Apr 2004 14:46:05 +0300

Hi All,

Currently, XCAP-CPCP [1] includes the definition of data elements for
implementing authorization rules and permission rules (privileges) for
conferences. Along with the definition of those elements, it defines its
own rule syntax.

Common-policy [2] defines an authorization policy framework, intended
for use in different applications to control access to data. It includes
a syntax for common policy rules that are currently being used to
describe authorization policies in location and SIP presence
applications. Also, the common policy framework can be extended to
accomodate other application needs.

In short, this framework defines policy as a set of rules where the
respective ordering of rules does not matter. Each rule consists of a
condition for matching some property (e.g., identity of the requestor of
data); and permissions that are to be applied in case the "condition"
part has evaluated to true.

It seems natural that the conference policy work would also benefit from
adopting the common-policy framework.

However, one of the intended usages of conference policy is to control
the participation to a conference. To expel a participant from an
ongoing conference, the conference policy would be manipulated in such a
way that the participant is no longer allowed to participate, effecting
a removal of that participant from the conference. The need for
expelling users is also independent of the original admittance policy.
Even in conferences that have open admittance (i.e. anyone can join), a
moderator would need to be able to expel users who are disturbing the
conference, e.g., expel a participant from a chat room for using
explicit language.

In common-policy point of view, the above would require an "all-except"
construct, which I believe currently is not allowed in common-policy.
Question is, can this be worked around, if we were to adopt
common-policy in the conference policy work?

And if yes, would XCON be willing to see common-policy adopted in the
conference policy work?

The advantages would include having a unified syntax for policy rules in
these different applications, including a clear extension model etc.

Disadvantages (pending the resolution of the above issue) would be
having to rewrite the authorization policy parts of XCAP-CPCP, causing a
delay.

Thoughts?

Cheers,
Aki

[1]
http://www.ietf.org/internet-drafts/draft-koskelainen-xcon-xcap-cpcp-usage-02.txt

[2]
http://www.ietf.org/internet-drafts/draft-ietf-geopriv-common-policy-00.txt

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