Formal Characterization of Active Databases
Chitta Baral and Jorge Lobo
Abstract
In this paper we take a first step towards
characterizing active databases. Declarative
characterization of active databases allows additional flexibility
in studying the effects of different priority criteria between
fireable rules, different actions and event definitions,
and also to make claims about effects of transaction
and prove them without actually executing them. Our
characterization is related but different from similar attempts by Zaniolo in
terms of making a clear distinction
between actual and hypothetical execution of
actions and
allowing non-determinism. We use the `choice' construct to
characterize the non-determinism that arises when several rules can
fire at the same time and the preference between them is not
specified. We show through examples how
our language allows us to express features of different
active database systems.