+---------+
                           |  Floor  |
                           |  Chair  |
                           |         |
                           +---------+
                              ^   |
                              |   |
                 Notification |   | Decision
                              |   |
                              |   |
                   Floor      |   v
+-------------+   Request  +---------+              +-------------+
|    Floor    |----------->|  Floor  | Notification |    Floor    |
| Participant |            | Control |------------->| Participant |
|             |<-----------|  Server |              |             |
+-------------+ Granted or +---------+              +-------------+
                  Denied