urrent choreography languages are specification languages. They are used at design time to define a mutual contract between services that are under the supervision of different domain controllers. Choreography contracts are established by specifying the observable sequence of messages that are exchanged between services. Some service collaborations only make sense in a particular context, and have a short life-cycle. Hence, there is a need for mechanisms that support on-demand deployment of peer-to-peer collaborations. The ECF proposes to express the global contracts between domains using business rules rather than application-specific messages sequences. Service collaborations can then evolve and be deployed in a more flexible way. ECF uses a distributed aspect platform to enable dynamic superimposition of collaboration activities. ECF also defines a relationship between the distributed composition units and global collaboration models, so that the correctness of ECF choreographies can be checked for using existing service composition modeling tools.