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Conference Control

It should be clear that not all conferences need an explicit conference control system, and not all conferences need to utilise the services provided by the CMMC. If video, audio and shared workspace are all provided in an entirely distributed fashion (as with the LBL whiteboard and IVS), no additional conference control system is required, since membership and participation are handled by the multicast group mechanism of the Mbone. If, however, any of the additional video, audio or shared workspace functionality outlined above are required, then some additional form of explicit conference control is required.

The conference control system for the MICE CMMC will be based on the CAR Conference Control system from UCL. The basic conference control functions are:

• Creation and deletion of conferences
• Joining and leaving conferences
• Introducing applications to the conference
• Floor control
• Control of conference video channel(s)

Currently, this functionality is provided by a centralised Conference Server, remote Conference Management Applications, and a number of applications that communicate with the conference server using remote procedure calls from the CAR library. In the long run we hope to substitute a more distributed and fault tolerant conference control model to be known as the Conference Communication Channel Protocol (CCCP), but this is not likely to occur within the timescales of the existing project.

This basic conference control functionality provides the information for applications to locate the remote machines for running clients, and a simple floor control scheme for those applications that require it. It also provides information for video and audio servers to:

• allocate channels and codecs where required;
• give control over the multiplexing of those channels where this is not
• handled by applications such as IVS;
• to perform bandwidth and quality of service reservation where networks
• provide such functionality.

It should be stressed that the conference control system itself does not provide these resource allocation functions; this is handled by the resource allocation part of the CMMC. This split of functionality keeps the conference control system minimalist, so that it can also be used outside of the CMMC when resource allocation is not required. The Conference Control system and the Booking and Resource Allocation systems are shown in Fig. 6.