The Coordination Language Facility: Coordination of Distributed Objects

The development of communication infrastructures and the rapid growth of networking facilities in information technologies increase information mobility and the decentralisation of work processes in industry and services. This evolution leads to increasing demands on the coordination of information systems. However, information technologies available today are capable of supporting only interoperability of information systems from the point of view of communication infrastructures. This makes possible an easy exchange of information but provides no support for coordination. To fill this gap, we propose the Coordination Language Facility (CLF) as a coordination layer on top of distributed systems infrastructures such as CORBA-compliant Object Request Brokers. The CLF provides support for the coordination of heterogeneous, possibly distributed, active objects within larger units implementing (work) processes. On one hand, coordinator objects are declaratively implemented as rules. On the other hand, the objects participating in a coordination (participants) must instantiate a minimal interface which specifies the negotiation dialogue invoked, at run-time, by coordinators. The coordination activity is split between the implementation of the interface on the participants’side and the execution of the rules on the coordinators’ side, thus offering a clear separation of concerns between local and global activities. The interface is specified using the CORBA standard for distributed objects, removing issues of heterogeneity and allowing each component to be implemented in the most appropriate language and environment.