+------------+      +------------+
| FOREGROUND |      | BACKGROUND |
| JOB        |      | JOB        |
|            |      |            |
+------------+      +------------+
| Q ELEMENT  |            |
+------------+            |
     |                    |
     |                    |
     v                    v
+------------+      +------------+
|  MONITOR   |      |  MONITOR   |
|            |      |            |
+------------+      +------------+
     |              | Q ELEMENT  |
     |              +------------+
     |                    |
     +------------+       |
                  |       |
                  v       v
              +----------------+
              | DEVICE HANDLER |
              |                |
              |                |
              +----------------+
                      |
                      |
                      v
                +------------+
                |   DEVICE   |
                |            |
                +------------+