@startuml


:Passenger:
:Driver:
:Operator:

left to right direction

  Passenger -- (1. Ordering taxi) : (1) name time\nand location
  Operator -- (1. Ordering taxi) : (2) receive and record
  Operator -- (2. Finding available driver) : (3) ask for\nlocation
  Driver -up-- (2. Finding available driver) : (1) report\nlocation
  Driver -up-- (3. Driving) : (5) pick-up and deliver
  Passenger -- (3. Driving) : (6) pay

@enduml