Appropriate abstractions must be available in order to properly design and implement CPEs, including tasks such as the control of and cooperation among their participating entities.
Services model the functionality offered by brokers.
Triggers are used in most approaches surveyed above. Constructs for the Design and Implementation of Process-Oriented Environments. Technical Report 95.26, Computer Science Department, University of Zurich, 1995. Doc 50 Research Directions in Concurrent ObjectOriented Programming - Agha, Wegner et al.