interface I {
  in void e();
  behaviour {
    on e: {}
  }
}

component C1 {
  provides I p;
  requires external I r1;
  requires external I r2;
  behaviour {
    on p.e(): {}
  }
}

component C2 {
  provides I p;
  behaviour {
    on p.e(): {}
  }
}

component S1 {
  provides I p;
  requires I r;
  system {
    C1 c1;
    C2 c2;
    p <=> c1.p;
    c1.r1 <=> r;
    c1.r2 <=> c2.p;
  } 
}

component S2 {
  provides I p1;
  provides I p2;
  requires external I r1;
  requires external I r2;
  system {
    S1 s1;
    p1 <=> s1.p;
    p2 <=> r2;
    r1 <=> s1.r;
  }
}