Specifying global behaviour in database federations

We discuss the impact of locally implemented behaviour on global behaviour specification in a federation of object-oriented databases. In particular, given a specification of an integrated view of a number of component databases, we discuss the process of determining the global methods that are implicitly implemented by a given set of local methods on these component databases. To this end, we develop the notions of objectivity and subjectivity of local methods, indicating whether the execution of a local method affects the global view exactly as it affects the local database, behaviour equivalences between local methods, indicating whether local methods of different components have similar effect, and behaviour concurrences, indicating whether local methods respond to the same event. These notions can be used as a basis for tools supporting the engineering activity of specifying global behaviour in database federations