+----------------+
                 | main_sup       |
                 +--------+-------+
                          |
         +----------------+----------+
         |                           |
 +-------+-------+            +-------+--------+
 | master_worker |            + slave_sup      |
 +---------------+            +-------+--------+
                                     |
                               +-----|---------+
                             +-------|--------+|
                            +--------+-------+|+
                            |  slave         |+
                            +----------------+