@startuml
skinparam BackgroundColor F0F0F0

actor User
participant "A2DP Sink" as sink
participant "Source's AVRCP event handler" as source
participant "Service Bluetooth" as bt
participant "Service Audio" as audio
participant "Settings" as settings
participant "Application" as app 


User -> sink : Volume button pressed
==A2DP==
sink -> source : AVRCP volume changed 
== ==
source -> bt : Volume changed message
bt -> audio : Volume changed message
audio -> settings : Set appropriate value
audio -> app : Current volume changed
app -> User : Show current volume level

@enduml