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InstantMessagingMcuSession

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The InstantMessagingMcuSession class represents the Instant Messaging-specific implementation of the media-agnostic McuSession class. The class encapsulates operations and events relevant to the Instant Messaging Multipoint Control Unit (MCU).

InstantMessagingMcuSession State Transitions

The InstantMessagingMcuSession state transitions are shown in the following illustration.

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  1. The transition from Idle to Active occurs after ConferenceSession has joined a conference. An InstantMessagingMcuSession instance can become active either before or after the callback passed to BeginJoin() is called, depending on when the MCU is activated on the server.

  2. The transition from Idle to Terminated occurs when the parent ConferenceSession object joins a conference that does not support the same MCU type (for example, when an attempt is made to join an IM-only conference to an AudioVideoMcuSession instance).

  3. The transition from Active to Retrying occurs when the Focus detects that the MCU is failing over. In this case, Microsoft Unified Communications Managed API (UCMA) 3.0 Core SDK terminates the call with that MCU, provided that the call already exists. This transition also occurs when the ConferenceSession object reconnects to the Focus. Because the MCU is not known to be failing over, the call is not terminated in this case.

  4. The transition from Retrying to Active occurs when the failover process is complete, or when the ConferenceSession has reconnected to the Focus and the MCU is active. It is possible for the ConferenceSession to reconnect to the Focus, but the InstantMessagingMcuSession state does not change to Active if the MCU has not been activated on the server.