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This appendix contains the definition and specification of the MIC-1 protocol for communication between the CMMC channel server (CH) and a remote codec controller (RC). Whether the remote codec controller actually sets the codec parameters itself or via a third party (either software or human) is up to the implementation of the remote codec controller. However, it is normally expected that the protocol will be used directly by the software controlling the codec itself. See section 10.2.1 for a further description of this protocol.
This section contains a definition of the protocol syntax and a state transition diagram which together are intended to define the protocol. It also contains a sample time-sequence diagram which is included more as an example than for definition purposes, and an example of a state report message.
It is the responsibility of the remote codec controller to make the TCP connection to a well known port on the CMMC which initiates the exchange, and to declare the protocol being used. The protocol needs to be declared as one well known port will be used for all incoming control connections to the Channel Server, whether from remote codec controllers or otherwise.
A state report message can be sent by the RC at any time after the initial set_state message has been received. A state_report should be sent by the RC on any state change, such as the remote user hitting "stop sending". It should also be sent upon receipt of any state change request from the CMMC such as a stop_sending message, even if the remote codec had already manually been stopped by it's user.
A slightly unusual example: if the codec stops sending because of a manual request from it's user, it should immediately send a state_report stating that it has stopped sending. This will cause the CMMC to send a stop sending message to ensure that the intended state is consistent. The RC should reply with another state report as an indication that it now knows it is expected to have stopped. This sort of message redundancy is only necessary if the RC is not under the total control of MIC-1.