RE: [XCON] CPCP Requirement: Repeat times

[hisham.khartabil at nokia.com]

Admittedly, the current solution specifies that a convener needs to change the stop time in order to terminate the conference, if he wants the conference to end as he leaves. I sense that people want the convener to explicitly indicate that instead of just modifying the stop-time. Am I correct? I know Brian wants it so.

I also would like to encourage people to read sections 12 and 18.3 of the solution draft. Those sections discuss exactly what this thread is all about.

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

Regards,
Hisham

> -----Original Message-----
> From: xcon-admin@ietf.org [mailto:xcon-admin@ietf.org]On Behalf Of ext
> Michael Hammer
> Sent: 06.February.2004 21:49
> To: Rosen, Brian
> Cc: Koskelainen Petri (Nokia-NRC/Tampere); fluffy@cisco.com; Rosen,
> Brian; drage@lucent.com; klantz@cisco.com; xcon@ietf.org;
> dbieseli@cisco.com
> Subject: RE: [XCON] CPCP Requirement: Repeat times 
> 
> 
> Brian,
> 
> I may be a little confused by what is meant by policy and policy 
> manipulation with respect to how that translates into resources being 
> invoked and released.  My vision (delusion) as to how that 
> might work might 
> have to wait to see the actual protocol develop.  But, I 
> suspect that your 
> answers to my comments below will help clear this up for me.
> 
> Mike
> 
> 
> At 01:33 PM 2/6/2004 -0500, Rosen, Brian wrote:
> > > >End when last person leaves is the way many bridges work.
> > >
> > > Is that a technical justification?
> >Actually, I think it means there is a requirement for that 
> to be possible.
> 
> Agree.  Don't see that as not possible.
> 
> 
> > >
> > > >You might
> > > >not like it, but that's the way they work.  Most bridges don't
> > > >start if the convener is not there.  If he arrives, and 
> then leaves,
> > > >the conference is over.
> > >
> > > What is the meaning of conference policy then?  I thought
> > > that it was an
> > > authorization for something to take place.  If the conference
> > > is authorized
> > > to start and someone shows up, then it starts.  If it is
> > > authorized to
> > > stop, and the bridge resources are needed elsewhere, then 
> it stops.
> >CPCP has two elements, and they each have a role in policy.
> >A particular implementation, or more properly, a particular 
> administrative
> >action, may restrict the range of possible policy requests 
> the convener
> >may ask for.   The bridge may not respond the way the 
> convener would like
> >it to.  It must be possible for the bridge to have local 
> policy, and yet
> >allow the convener to manipulate whatever freedoms the local policy
> >permits.
> 
> I agree with this part.  The local "uber-policy" determines if the 
> convener's policy request is accepted or rejected.
> 
> 
> >You could have the bridge change the start/stop time itself
> 
> I don't follow this part.  It seems to confuse the role of 
> the bridge in 
> committing to the use of resources and the role of the convener in 
> committing to pay for what he has asked for.  If it is the 
> intent of the 
> requester to terminate the conference upon his leaving, then 
> that should 
> be  an option of the request he makes to the bridge.
> 
> If he is requesting that the bridge terminate upon his 
> departure, shouldn't 
> that be an update to his policy?  Same for other options.  
> The bridge of 
> course may have resource limitations, and thus there may be 
> conditional 
> authorizations to what is requested.  Where I think I have 
> some confusion 
> is that some of these options/authorizations are implicit not 
> explicit.
> 
> >to implement
> >its local policy, but that makes the function even more twisted.
> >Better to have explicit mechanisms, and let the bridge 
> implement, or permit
> >a subset of them if it wishes.
> >
> > >
> > > >It also doesn't work to manipulate stop time to end the
> > > conference because
> > > >its the bridge that wants to enforce its policy and not 
> the convener.
> > >
> > > Who is the authority here?  Isnt' the bridge-providing
> > > service supposed to
> > > obey policy?
> >As above, local policy must override.
> 
> I agree, in the sense that local policy drives convener 
> policy that drives 
> bridge resource provided/withheld.
> 
> 
> >....snip...
> > > strategy, and an implementation detail.  It seems the
> > > confusion here stems
> > > from not separating:
> > >
> > > Is a conference authorized at the moment,
> > > Is a bridge needed at the moment,
> > > and should a bridge be reserved at the moment.
> >I don't see it that way.  I see it as the bridge has local policy,
> >the convener wants to exert whatever freedom the local 
> policy permits,
> >and the participants have to have some way to understand what is
> >going to happen.
> 
> But, isn't the time at which the local policy interacts with 
> the convener 
> request independent of when a particular bridge resource gets 
> assigned?  A 
> convener request could be accepted so long as there are 
> enough resources 
> available/reserved in the pool, whether or not a resource is 
> actually put 
> to use.
> 
> 
> > >
> > > >We have to be explicit.
> > >
> > > Yes, particularly as to the semantics of policy.  What does
> > > start time
> > > mean?  What does stop time mean?  I keep seeing primary
> > > meanings tangled up
> > > with secondary and tertiary implementation implications.
> >I've proposed that start time is the earliest time at which
> >mixing starts.
> 
> I thought this was a policy?  This would mean that the start 
> time would be 
> the earliest time at which mixing is permitted to start.  Isn't this 
> independent of whether a resource was invoked?  Note, it may 
> be reserved 
> un-occupied and billed for, but that may not be the most 
> efficient use of 
> resources.  (No statistical over-booking allowed.)
> 
> 
> >I've proposed that stop time is interpreted by the stop time
> >enumeration.  It could be a hard stop of mixing resources, or it
> >could be only advisory.
> 
> Could this not be defined as the latest time at which mixing 
> is permitted 
> to be used, i.e. that the enumeration option is whether the 
> stop time may 
> get updated explicitly by the convener or another party or 
> implicitly by a 
> convener agent (could be the bridge)?
> 
> 
> > >
> > > >As to Cullen's objection, what you are worried about is 
> start time,
> > > >and not stop time.  By your definition, the conference 
> never started.
> > > >If it did start, then it ends when whoever showed up leaves
> > > (if that's
> > > >what the conference policy was set to), or when the 
> convener leaves,
> > > >which is surely the right thing.  I don't know how to fix
> > > your problem
> > > >actually.   Maybe some kind of action that resets start.
> > >
> > > The bridge may need to be released and re-captured, but that
> > > does not mean
> > > the conference is re-started.
> >Possibly a minor semantic argument.  I think we both agree that
> >the scheduled conference did not take place.
> 
> Are we talking when a convener was authorized to invoke a conference 
> resource or accounting for when resources were actually used?
> I believe that some conference services still charge as the 
> resources where 
> reserved and represent an opportunity cost.
> 
> >What is the
> >difference between "release and recapture" and "reset start"?
> 
> One appears to be a new conference instance, while the other 
> appears to be 
> a modification of an existing conference.
> 
> 
> > >
> > > >   The problem is,
> > > >that would have to be a convener action; you wouldn't want a
> > > participant
> > > >to invoke it.
> > > >
> > > >Also, Petri, you can't implement a "Meet Me" with
> > > start/stop.  MeetMes don't
> > > >have start and stop times.
> > >
> > > You are asserting what the group is attempting to define.
> >Well, we can twist start and stop, but to any person, a meet me, by
> >definition, does not have start and stop times.  Could we 
> implement it
> >by twisting start/stop?  I guess, but I don't think its a good idea.
> >
> > >
> > > >   They start whenever the convener arrives,
> > >
> > > What if the convener never arrives, but the rest of the group
> > > does?  To say
> > > it never starts seems rather limiting in an unnecessary way.
> >That's the way Meet Me (notice the word "Me") services are defined.
> 
> I should note that the term "meet me" has been used in a more 
> broad way to 
> mean any pre-scheduled conference for which a number 
> (address) has be setup 
> and to which users are asked to call into at some future 
> time.  You seem to 
> have something more specific in mind.  I have no problem with 
> a specific, 
> maybe trademarked, service to be more narrowly defined, but 
> see no reason 
> to limit other possibilities.
> 
> >I happen to think its an excellent service.  I would not want anyone
> >to be able to use my Meet Me conference if I was not there.
> >I am charged for it.  If 4 people know my MeetMe URI, they can decide
> >to have a conference (on my nickle) any time they want if there is
> >not a restriction that convener starts.  That is precisely why MeetMe
> >works the way it does.  Its not a current technology limitation.
> 
> I have not problem with this being possible, just don't think 
> CPCP should 
> be restricted for being used in other ways.  Protocol should 
> be generally 
> usable for many types of services.
> 
> >I have no problem at all in allowing CPCP to facilitate an ad-hoc
> >conference, which is what I think you are looking for.  Ad-hoc is
> >a conference starts either by promoting a one on one to a three way,
> >or by the first person connecting to the conference, and it ends when
> >the last person leaves (or for some, when the number of participants
> >drops below 3).  Ad-hoc is also a useful service, but usually we use
> >ad-hoc internally where charging issues are simpler.
> > >
> > > >end
> > > >when he leaves (usually),
> > >
> > > This again is not necessary.  A convener (payer) may want to
> > > start the
> > > conference, but not stay for the full discussion.  No reason
> > > the conference
> > > can not continue without that person, if the policy says it can.
> >Agree, but I want you to explicitly say that, and I want local policy
> >to be able to permit you to say that, or deny you the 
> ability to say that.
> 
> OK
> 
> 
> > >
> > > >but restart when he arrives again with out regard
> > > >to start and stop.
> > >
> > > A new start and stop time is a new conference, perhaps an ad hoc
> > > one.  There is no reason the conference policy would restrict
> > > the convener
> > > from scheduling multiple conferences, unless there is other
> > > local policy
> > > that over-rides the ability to do so.  But, that again is
> > > implementation.
> >Well, a new start/stop MAY be a new conference, or it could 
> be a reschedule
> >of an existing one.  Take a scenario where a couple of 
> participants show,
> >the convener doesn't, and the participants leave.
> 
> Hopefully, the convener could show up late and the conference 
> is still 
> active and resources get invoked for him and whoever else 
> shows up late.
> 
> >The convener pushes
> >start and stop an hour.  If its a new conference, there is a 
> new conference
> >URI.
> >If its a reschedule, then its the same conference, and the 
> same URI.  I
> >think
> >that is preferable.
> 
> So long as the convener shows up within the hour it was originally 
> scheduled, could it be neither a new conference nor a 
> reschedule?  Suppose 
> he shows 20 minutes late, but only needs 40 minutes to get 
> the work done, 
> why should any policy change take place?
> 
> 
> >Local policy, as I advocate, is indeed a controlling factor. 
>  However, to be
> >successful, the convener and the participants have to know 
> what the local
> >policy is, so that their expectations are met.  That means 
> CPCP has to have
> >ways of the participants including the convener to learning the local
> >policy,
> >which means the language has to have the ability to express 
> it.  It's not
> >just implementation.
> >
> > >
> > > I hope the tone of the above does not sound harsh.  I just
> > > think it would
> > > be useful to separate the definition of "what" the conference
> > > is from the
> > > definition of "how" it is to be supported.
> >Confused about "what a conference is".  I think we are all 
> working on the
> >"how it is to be supported".  I don't even want to think 
> about a definition
> >of what it is.  For example, if I play music on hold to you 
> while you are
> >waiting for a conference to start, is that part of the conference?
> 
> That sounds like a service description which may be 
> implementation dependent.
> 
> >You got
> >there with the conference URI, you can probably manipulate 
> some resources
> 
> 
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