@startuml "Simple messaging"
actor       Sender as snd
actor       Receiver   as rcv
control     Server     as srv
collections msg as msg
queue       msgch       as msgch
collections dvyrq as dvyrq
collections dvy as dvy
queue       dvych as dvych

rcv->srv: Listen
srv->msgch: Subscribe
snd->srv: Send message
srv->msg: Store message
srv->msgch: Notify listening receivers
msgch->srv: Notify
msg->srv: Grab message
srv->rcv: Send message

@enduml