Re: [bfcpbis] 4582bis terminology

Alan Ford <alan.ford@gmail.com> Thu, 20 September 2018 16:30 UTC

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From: Alan Ford <alan.ford@gmail.com>
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Date: Thu, 20 Sep 2018 17:30:17 +0100
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To: Christer Holmberg <christer.holmberg@ericsson.com>
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Subject: Re: [bfcpbis] 4582bis terminology
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Hi Christer,

Hmm. I think we might be ok here.

A Floor Participant will communicate with the FCS just as the Floor Chair will. The Floor Participant will request information from the FCS - that bit seems fine to me.

This text is all very weird though, and designed for BFCP as it was originally specified, and not the very simple implementations we meet in the world today. All that’s actually implemented in the real world has a FCS and Floor Chair being the same, and holding s-only role, and then a Floor Participant is a client (c-only role). And that’s it. 

There isn’t any FCS + Chair communication on the wire. I can see that if there was, then this text may make more sense. But then it’s talking about “logical entities” so I guess it holds.

The problem, I think, is with the text about different roles being determined per-transaction. That doesn’t really map to the way BFCP is used in the real world, but fundamentally the protocol (4582bis) doesn’t prevent the three logical entities all passing messages and changing roles. We only nail this down to fixed roles in 4583bis through the SDP exchange.

So I guess what I’m saying is I think this text is probably ok as-is.

Regards,
Alan

> On 20 Sep 2018, at 11:48, Christer Holmberg <christer.holmberg@ericsson.com> wrote:
> 
> Hi,
>  
> I took a look at the 4582bis terminology, and I am a little confused.
>  
> We have the following definitions:
>  
>    Client: A floor participant or a floor chair that communicates with a
>    floor control server using BFCP.
>  
>    Floor Control Server: A logical entity that maintains the state of
>    the floor(s), including which floors exists, who the floor chairs
>    are, who holds a floor, etc.  Requests to manipulate a floor are
>    directed at the floor control server.  The floor control server of a
>    conference may perform other logical roles (e.g., floor participant)
>    in another conference.
>  
> So far, so good, I think. 4582bis does not define “client” and “server” as roles, though.
>  
> Then there is:
>  
>    Floor Chair: A logical entity that manages one floor (grants, denies,
>    or revokes a floor).  An entity that assumes the logical role of a
>    floor chair for a given transaction may assume a different role
>    (e.g., floor participant) for a different transaction.  The roles of
>    floor chair and floor participant are defined on a transaction-by-
>    transaction basis.  BFCP transactions are defined in Section 8.
>  
> Still ok, I think. The chair is per transaction, so both a client and server can act as floor chair.
>  
> But, then there is:
>  
>    Floor Participant: A logical entity that requests floors, and
>    possibly information about them, from a floor control server.  An
>    entity that assumes the logical role of a floor participant for a
>    given transaction may assume a different role (e.g., a floor chair)
>    for a different transaction. 
>  
> First, it says that a floor participant request floors from a floor control server. My understanding of that is that the floor participant is always the client, which means it stays the same throughout the session (due to the c-s removal in 4583bis).
>  
> Second, the text says that the role is per transaction, which would mean the client/server thing is also per transaction.
>  
> Is there a bug? Should the text say:
>  
>    Floor Participant: A logical entity that requests floors, and
>    possibly information about them, from a floor chair. 
>  
>  
> Regards,
>  
> Christer
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