ConferenceSession State Transitions

A conference represents an online meeting place for participants to discuss topics of interest, using one or more media types, such as instant messages or audio-video. A two-party conversation can be escalated to a conference. In Microsoft Unified Communications Managed API (UCMA), the ConferenceSession class implements the signaling functionality of a Centralized Conference Control Protocol (C3P) conference signaling session.

ConferenceSession State Transitions

The following illustration shows the possible state transitions on a ConferenceSession instance.

1. The transition from Idle to Connecting occurs when BeginJoin is called.

2. The transition from Connecting to Connected occurs when the join process is complete. In the Connected state, ParticipantEndpointAttendanceChanged events are raised for all existing participant endpoints in the Focus and MCUs before the callback method in the argument list of BeginJoin is called.

3. The transition from Connected to Disconnecting occurs when any of the following occur:

   • The application called BeginTerminate on the Conversation instance.

   • The application called BeginTerminateConference on the ConferenceSession instance.

   • A local participant was ejected from the conference.

   • The conference was terminated.

   • The parent Conversation failed an escalation attempt.

4. The transition from Disconnecting to Disconnected occurs when the call to BeginTerminateConference on the ConferenceSession instance succeeds. The termination process is complete. Signaling and subscription sessions with the Focus are terminated before this transition occurs. This transition also happens when passive cleanup is complete; that is, when a participant is ejected, and the object has been garbage-collected.

5. The transition from to Disconnecting to Idle occurs only when the parent Conversation has failed an escalation attempt. Before the transition to Idle occurs, ConferenceSession state is cleaned up and ParticipantEndpointAttendanceChanged events are raised for all participant endpoints associated with this ConferenceSession and its child McuSession objects.

6. The transition from Connected to Reconnecting occurs if the front end that hosts the Focus has failed over. During this transition, all pending ConferenceSession operations fail. Any operation requested from ConferenceSession after its state changes to Reconnecting will fail with a RealTimeInvalidOperationException with a failure reason of RetryableOperation. This transition also occurs when the communication channel (SIP dialog) is in recovery mode.

7. The transition from Reconnecting to Connected occurs when the reconnection process is successful. The Focus delivers a fresh roster that is compared to the existing roster information in ConferenceSession and its McuSession objects. Events are raised if any differences are detected.

8. The transition from Reconnecting to Disconnecting occurs if the reconnection attempt fails. Note that only one reconnection attempt is made.

9. The transition from Connecting to Idle occurs when the connection attempt fails, whereupon EndJoin throws an exception.

10. The transition from Connecting to InLobby occurs when a participant attempts to join the conference, and the lobby is enabled on a Lync Server 2010 deployment.

11. The transition from InLobby to Reconnecting occurs if the front end that hosts the Focus has failed over. During this transition, all pending ConferenceSession operations fail. Any operation requested from ConferenceSession after its state changes to Reconnecting will fail with a RealTimeInvalidOperationException with a failure reason of RetryableOperation. This transition also occurs when the communication channel (SIP dialog) is in recovery mode.

12. The transition from Reconnecting to InLobby occurs when the lobby is enabled on a Lync Server 2010 deployment, and the reconnection process is successful. The Focus delivers a fresh roster that is compared to the existing roster information in ConferenceSession and its McuSession objects. Events are raised if any differences are detected.

13. The transition from InLobby to Connected occurs when the participant is admitted into the conference by the leader.

14. The transition from InLobby to Disconnecting occurs when a participant is ejected from the lobby, the conference is terminated, or BeginTerminate is called.