5.3 Direct multiple out events

A requires port inevitably triggering multiple out-events (r.a, r.b) is implemented as one function call for each out-event posting in the component queue, followed by a single flush call to trigger component processing of the events. The below 2 versions of the component are indistinguishable looking from the outside.

Notice that the interface declares that a and b are executed atomically. While in the behavior of the component each event is handled or forwarded independently. However to an observer of the provides interface of the component a and b are again executed atomically.

interface I
{
  out void a ();
  out void b ();
  behavior
  {
    on inevitable: {a; b;}
  }
}

component direct_multiple_out1
{
  provides I p;
  requires I r;
  behavior
  {
    on r.a (): p.a ();
    on r.b (): p.b ();
  }
}

import direct_multiple_out.dzn;

component direct_multiple_out2
{
  provides I p;
  requires I r;
  behavior
  {
    on r.a (): {}
    on r.b (): {p.a (); p.b ();}
  }
}

The third variant is left as an exercise to the reader.