relies on a woker
  and a client on a server to get the job done.
</p><p>The interfaces in this library 
  give some guarantees related to reliability, 
  but there are also some pitfalls:
</p><ul><li> A client using timeouts can be sure that 
      the requested service has been performed
      when the reply arrives before the timeout expires.
      If no reply arrives before timeout expiration,
      no such claim can be made (in particular not
      that the service has not been performed).
      The se