This paper describes an active object-oriented mediator for the enforcement of global consistency between relational legacy databases. We discuss the problem of integrating several local relational systems into a federated system by the usage of an object-oriented mediator system. We explore how relational DBMSs can be enhanced to signal local updates that may violate global constraints without...

This paper reviews research on the formal speciication of active behaviour, indicating both what has been done in this area, and how. The scope of diierent approaches is compared within a common framework, which reveals that although many aspects of active behaviour have been described formally, no single proposal covers all phenomena associated with active database systems.

Active Database Systems (ADBSs) provides a good infrastructure to define and execute active rules. Nevertheless, this infrastructure offered by ADBSs does not completely satisfy the necessities of rules management that demands current business applications. Rules also need to be stored in appropriate structures to facilitate their management, as the existing structures for data in these systems...

A substantial portion of web traffic consists of queries to database web servers. Unfortunately, a common technique to improve web scalability, proxy caching, is ineffective for database web servers because existing web proxy servers cannot cache queries. To address this problem, we modify a recently proposed enhanced proxy server, called an active proxy, to enable Active Query Caching. Our app...

Integrity Maintenance is considered one of the major application elds of rule triggering systems (RTSs). In the case of a given integrity constraint being violated by a database transition these systems trigger repairing actions. However, it has be shown that for any set of constraints there exist unrepairable transitions, which depend on the closure of the constraint set. This implies that int...

XML (Extensible Markup Language) has recently emerged as a new standard for data representation and exchange on the Internet. It is expected that XML will become a universal format for data exchange on the Web. There is a need for an efficient XML database system that can be used to manipulate and process XML data. Trigger mechanism is a mature technique in Active Database Systems for providing...

We propose a new formal semantics of active databases based on a transaction rewriting technique in the context of the relational model. A user deened transaction, which is viewed here as a sequence of atomic database updates forming a semantic unit, is translated by means of active rules into induced one(s). Those transactions embody active rule semantics which can be either immediate or defer...

Active databases and real-time databases have been important areas of research in the recent past. It has been recognized that many beneets can be gained by integrating active and real-time database technologies. However, there has not been much work done in the area of transaction processing in active real-time databases. This paper deals with an important aspect of transaction processing in a...

This paper presents the space-filling curves and their applicability in scheduling, especially in transaction scheduling in Active Real-time Database Systems (ARTDBS). Active real-time databases have emerged as a research area in which concepts of active databases and real-time databases are combined into a real-time database with reactive behaviour. A novel space-filling curve based approach f...

We give a method for improving the e ciency of condition evaluation during rule processing in active database systems. The method derives, from a rule condition, two new conditions that can be used in place of the original condition when a previous value (true or false) of the original condition is known. The derived conditions are generally more e cient to evaluate than the original condition ...