Coordinating Peer Databases Using Eca Rules

Peer databases are stand-alone, independently developed databases that are linked to each other through acquaintances. They each contain local data, a set of mapping tables and expressions, and a set of ECA rules that are used to exchange data among them. The set of acquaintances and peers constitutes a dynamic peer-to-peer network in which acquaintances are continuously established and abolished. We present techniques for specifying data exchange policies on-the-fly based on constraints imposed on the way in which peers exchange and share data. We realize the on-the-fly specification of data exchange policies by building coordination ECA rules at acquaintance time. Finally, we describe mechanisms related to establishing and abolishing acquaintances by means of examples. Specifically, we consider syntactical constructs and executional semantics of establishing and abolishing acquaintances.