1. A method for policy-based control of a communication network having a distributed architecture, including at least one heterogeneous communication network, the method comprising: messaging between network elements, said network elements comprising at least one policy enforcement point (PEP) and one or more policy decision points (PDPs), said messaging including: the at least one PEP announcing event notification capability information of the at least one PEP to make the event notification capability information available to the one or more PDPs, and subscribing the one or more PDPs to at least one event notification capability of the at least one PEP; sending notifications of the occurrence of events subscribed to by the one or more PDPs; and the at least one PEP enforcing a policy upon said events if certain conditions are met, wherein, in case of the at least one PEP receiving from multiple ones of the one or more PDPs multiple suggestions to enforce said policy, a preference-or priority scheme is applied by said at least one PEP for selecting one of the suggestions to enforce said policy upon.