This is a multi-part example that displays PLEXIL's capabilities for directed
communication. There are two actors and one controller in this system. The two
actors are front_engine and rear_engine. Each engine has one lookup, Torque, and
can process one command, setTorque. The controller plan swaps the torque of the
front and rear engines.

To run these examples, first compile each PLEXIL file:

  plexilc controller.ple
  plexilc front_engine.ple
  plexilc rear_engine.ple

Then run these commands, in sequence, in separate shells:

  ipc
  plexilexec -p front_engine.plx -c front_engine-config.xml
  plexilexec -p rear_engine.plx -c rear_engine-config.xml
  plexilexec -p controller.plx -c controller-config.xml
