hines instead of collaborations. The global goal is distributed to the roles, and similarly for condition, where the initiating role should be responsible for checking both its local condition and the condition relat- ing the roles. The BNF-grammar for local policy rules is defined in Figure 5.10, where Pred, E-role, C-role, and Signal are as for global policy rules described in <Policy rule> T : <Trigger> C : <Condition> A : <Action> G : <Goal> <Trigger> <Event> <Condition> Pred {, Pred, C-role.Pred+ } <Action> <Role-request> } }? PlayRole (E-role) <Goal> <Event> ? } <Message > <Message> ( Signal, C-role, C-role ) <Role-request> <Role-request> ( RoleReq (E-role), C-role, C-role ) Figure 5.10 Extended BNF syntax for local policy rules, with { }? denoting optional parts. (With kind permission from Springer Science+Business Media: J. E. Y. Rossebo and R. K. Runde. Specifying service composition using UML 2.0 and composition policies. In MoDELS 2008, Vol. 5301, LNCS, p. 531. Springer, Berlin, 2008.) Service Delivery Platforms Global rule Local rule, Local rule, initiating rule a participating role b T: ? (RoleReq (f) a, b) C: C, a.Ca, b.c C: C, Cal b.cb C: Cb A. Cu(e-a f-b) : A: ! (RoleReq (f) a, b, A: PlayRole (f) PlayRole (e) G: a.g b.gb G: ga G: gb Figure 5.11 From global to local policy rules. (With kind permission from Springer Science- Business Media: J. E. Y. Rossebo and R. K. Runde. Specifying service com- position using UML 2.0 and composition policies. In MoDELS 2008, Vol. 5301, LNCS, p. 531. Springer, Berlin, 2008.) Section 5.4. RoleReq(E-role) should be understood as a special signal, namely a request for playing the elementary (or subcomposite) role given as parameter. This means that a role request is a special kind of message. For a given global policy rule, the corresponding local rules may be derived automatically following the pattern given in Figure 5.11 as illustrated in Figure 5.12. 5.5.2 Local PESM Diagrams Local PESM diagrams are used to graphically depict local coordination and enforce- ment 