OnConnectionUserListChanged onConnectionUserListChanged =
         (List<TUIConnectionUser> connectedList,
          List<TUIConnectionUser> joinedList,
          List<TUIConnectionUser> leavedList) {};

OnConnectionRequestReceived onConnectionRequestReceived =
         (TUIConnectionUser inviter, 
          List<TUIConnectionUser> inviteeList,
          String extensionInfo) {};

OnConnectionRequestCancelled onConnectionRequestCancelled =
      (TUIConnectionUser inviter) {};

OnConnectionRequestAccept onConnectionRequestAccept =
      (TUIConnectionUser invitee) {};

  OnConnectionRequestReject onConnectionRequestReject =
      (TUIConnectionUser invitee) {};

OnConnectionRequestTimeout onConnectionRequestTimeout =
      (TUIConnectionUser inviter,
       TUIConnectionUser invitee) {};

void addObserver(TUILiveConnectionObserver observer);

 void removeObserver(TUILiveConnectionObserver observer);

Future<TUIValueCallBack<TUIConnectionRequestResult>> requestConnection
      (List<String> roomIdList,
       int timeout, 
       String extensionInfo);

Future<TUIActionCallback> cancelConnectionRequest(List<String> roomIdList);

Future<TUIActionCallback> acceptConnection(String roomId);

Future<TUIActionCallback> rejectConnection(String roomId);

 Future<TUIActionCallback> disconnect();