@startuml "Messaging with server delivery"
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 for messages
srv->msgch: Subscribe
snd->srv: Send message with delivery uid
snd->msg: Listen for delivery

group storeMessage
    srv->msg: Store message
    srv->dvyrq: Store delivery request uid=>Receiver
    srv->msgch: Notify listening receivers
end
msgch->srv: Notify
msg->srv: Grab message
srv->rcv: Cuts listening with message
srv->dvy: Store delivery done Receiver=>uid
srv->dvych: Notify listening Sender
dvych->srv: Notify
dvy->srv: Grab delivery
srv->snd: Cuts listening with delivery
@enduml