@startuml
'
'Basics: participant 
'Rename a participant using the as keyword.
'You can also change the background color of actor or participant.
'
actor Bob #red
' The only difference between actor
'and participant is the drawing
participant Alice
participant "I have a really\nlong name" as L #99FF99
/' You can also declare:
participant L as "I have a really\nlong name" #99FF99
'/
Alice->Bob: Authentication Request
Bob->Alice: Authentication Response
Bob->L: Log transaction
@enduml