[MEDIACTRL] msc-mixer: Discriminating between a non-existing connectionid and a non-existing conferenceid in <join>

[Jean-Francois Bertrand <jeffy at broadsoft.com>]

Section 4.2.2.2. of http://tools.ietf.org/html/draft-ietf-mediactrl-mixer-control-package-07  specifies that:

  "If id1 or id2 specify a conference identifier and the conference does
   not exist on the MS, the MS reports an error (406).  If id1 or id2
   specify a connection identifier and the connection does not exist on
   the MS, the MS reports an error (412)."

While there are well-defined rules on how to create a connectionid, the conferenceid is basically free-form.

How can one distinguishes between an non-existing conferenceid and non-existing connectionid in a <join> request?

thanks

/Jean-François Bertrand
Software Engineer
Broadsoft