Sequence Diagrams

less than 1 minute read

Sequence diagrams show process flow.


Dispatching calls:

  • solid arrows dispatch
  • dotted arrows return data
  • box the timeline to show lifetime of a dispatch


  • use frames for:
    • opt optional actions, followed by [condition]
    • loop looping behaviour, followed by [num loops] or [condition]
    • alt alternative actions, followed by [condition]


  • Free-form diagrams, good support for sequence diagrams

  • Fast and automatically formatted
  • Uses code defintions, like:
    title MotorControl
    actor A
    A->+SpeedControl: update(t, setpoint)
    SpeedControl->+Sensor: getSample()
    Sensor-->-SpeedControl: sensorData
    SpeedControl->Estimator: update(t, sensorData)
    opt t - tLast > ControlPeriod
    SpeedControl->+Estimator: getState()
    Estimator-->-SpeedControl: stateData
    SpeedControl->+Regulator: regulate(stateData, setpoint)
    Regulator-->-SpeedControl: commandTorque
    SpeedControl->Motor: actuate(commandTorque)