Events and Rules for JAVA: Design and Implementation of a Seamless Approach

Abstract

Public reporting burden (or this collection of information isS. Chakravarthy and R. Dasari PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)University of Florida PO Box 116120 Gainesville Florida 32611-6120 SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)Air This report investigates the re-designing and implementation of an active database subsystem in the JAVA environment. This was accomplished to overcome some of the limitations of the C + + environment in providing active capabilities to passive systems. Next to exploit some of the capabilities provided by the JAVA environment that would be applicable and used for an active system. Finally this provides a means for an active capability in the JAVA environment, as more and more OODBMS (Poet, ObjectStore etc.) and Distributed Systems are being developed in JAVA. Table 21 Figure 5 SUBJECT TERMS EVENTS AND RULES FOR JAVA: DESIGN AND IMPLEMENTATION OF A SEAMLESS APPROACH AbstractDuring the last decade, the paradigm of object-oriented software development has become one of the central means of developing software systems. In the object-oriented paradigm, applications are modeled as a set of interacting objects that require and provide services. This approach assumes that each object knows where the service is and calls it directly. However, this call-driven approach is not the only manner to invoke behavior. The proponents of active systems have proposed event-condition-action (ECA) rules, a mechanism where behavior is invoked automatically as a response to events but without user or application intervention. An active system automatically monitors events, evaluates conditions defined over the state of the system when the events occur, and invokes the action associated with the eventcondition pair based on the result of condition evaluation. Making a passive system active requires an expressive event specification language with well-defined semantics, algorithms for detecting the events, designing an event detector and implementing it. The environment (the programming language and the operating system) in which a system is built influences how the event detector is designed and implemented.Sentinel, developed at University of Florida, provides active capability to Open OODB, an object-oriented database management system (OODBMS) that was implemented in C++. However, C++ environment had certain limitations that proved deterrent to implementing some of the features of active capability. We tried to overcome these limitations by redesigning the active subsystem in Java, the most popular language now. Although both C++ and Java are both object-oriented languages, they differ in some of the capabilities they offer such as support for system calls, obtaining information of the application objects during run-time etc.This report discusses the re-designing and implementation of the active subsystem in the Java environment. There are three motivations behind our objective of re-designing and implementing the active subsystem in the Java environment. First, we would li...