ASIO

asio_sync_basic.dot

@startdot
digraph foo {
  program [shape=box, label="Your Program"]
  io_object [shape=box, label="IO Object"]
  io_service [shape=box, label="IO Service"]
  system [shape=ellipse, label="Operating System"]

  program -> io_object [label="1"]
  io_object -> program [label="6"]

  io_object -> io_service [label="2"]
  io_service -> io_object [label="5"]

  io_service -> system [label="3"]
  system -> io_service [label="4"]

  overlap=false
}
@enddot

reactor_pattern_structure.puml

@startuml
abstract class Reactor {
  handle_events()
  register_event()
  unregister_event()
}
interface EventHandler {
  handler_event()
  get_handle()
}
abstract class SynchronousEventDemultiplexer {
  select()
}
abstract class Handle

Reactor o-- "*" EventHandler : dispatches
Reactor ..> SynchronousEventDemultiplexer : <<use>>
EventHandler *-- Handle : owns
Handle "*" ..> SynchronousEventDemultiplexer : notifies
Reactor o-- "*" Handle : "handle set"
@enduml