Active object-relational mediators

The paper describes an active abject-oriented mediator for the enforcement of global consistency between relational legacy databases. The authors discuss the problem of integrating several local relational systems into a federated system by the usage of an object-oriented mediator system. They explore how relational DBMSs can be enhanced to signal local updates that may violate global constraints without sacrificing too much autonomy and present a database gateway for detection, logging and signalling. They show how the gateway is embedded into the architecture of an object-relational mediator system. They give a solution to the problem of mapping SQL commands to method calls in a C++ based system using a so-called mediator generator. Furthermore, they discuss how the federated system can be enriched by rule mechanisms that make the mediator behave actively.