@startuml
hide footbox
autoactivate on
skinparam sequenceParticipant underline
actor ":User" as usr
boundary ":Invite Member Form" as form
control ":Project Controller" as ctl
entity ":Project" as db_prj
entity ":User" as db_usr

usr -> form : // enters invited member's name()
form -> ctl : // send form()
ctl -> db_prj : // add new user's name to project database()
ctl <-- db_prj : // new user is an assistant
form <-- ctl
usr <-- form : inform that added user is an assistant
@enduml