Unifying user interfaces - session messages in a ``small'' conference

We illustrate how services and applications are unified using CCCP in figures 7.5 and 7.6.

  

Figure 7.5: Unifying Services with CCCP

Applications:

• An Audio Tool (at), registers as types: at, audio.send, audio.recv
• A Video Tool (vt), registers as types: vt, video.send, video.recv
• A Whiteboard (wb), registers as types: wb, workspace
• A Session Manager (sm), registers as types: sm, session.local, session.remote

The local hostname is x. There are a number of remote hosts, one of which is called y.

A typical exchange of messages may be as follows:

(1,video.recv,x)xxx (*,sm.remote,x)xxx From		   To		   Message
the following will be sent periodically:
(1,audio.recv,x) 		(*,sm.local,x) 		KEEPALIVE
(1,video.recv,x) 		(*,sm.local,x) 		KEEPALIVE
(1,wb,x)  		(*,sm.local,x) 		KEEPALIVE
 
the following will be sent periodically with interval 
dependent on conference size 
(1,sm,x)  		(*,sm.remote,*) 		I_HAVE_MEDIA text_user_name audio.recv video.recv wb
 
an audio speech burst arrives at the audio application from y
(1,audio.recv,x) 		(*,sm.local,x) 		MEDIA_STARTED audio y
session manager highlights the name of the person who is speaking
 
speech burst finishes
(1,audio.recv,x)        		(*,sm.local,x)          		MEDIA_STOPPED audio y
session manager de-highlights the name of the person who was speaking
 
video starts from z
(1,video.recv,x)        		(*,sm.local,x)          		MEDIA_STARTED video z
 
periodical reports:
(1,audio.recv,x)        		(*,sm.local,x)          		KEEPALIVE
(1,video.recv,x) 		(*,sm.local,x) 		MEDIA_ACTIVE video z
(1,wb,x)                		(*,sm.local,x)          		KEEPALIVE
 
someone restarts the session manager:
(1,sm,x)  		(*,*,x)    		WHOS_THERE
(1,audio.recv,x)        		(*,sm.local,x)          		KEEPALIVE
(1,video.recv,x)        		(*,sm.local,x)          		MEDIA_ACTIVE video z
(1,wb,x)                		(*,sm.local,x)          		KEEPALIVE
 
and so on...