<![CDATA[
                         +-------------+
                         |+-----------+|
                         ||           ||
                  +------>|   idle    |<------+
                  |      ||           ||      |
                  |      |+-----------+|      |
                  |      +------+------+      |
                  |             |             |
     "idle" recd. |             |"active" msg.| refresh timeout
 or content recd. |             |             | or 120s
                  |             |             |
                  |      +------V------+      |
                  |      |             |      |
                  |      |             |      |
                  |      |             |      |
                  +------+   active    +------+
                         |             |
                         |             |
                         +-------------+
]]>