Lightweight Object-Oriented Shared Variables for Cluster Computing in Java

Abstract

This paper describes a lightweight yet powerful approach for writing distributed applications in Java using shared variables. Our approach, called ShareHolder, is inspired by the flexible and intuitive model of information access common to the World Wide Web. The distributed applications targeted by our approach all share a weak consistency model, similar to a user's model of accessing e-mail, bulletin boards, chat rooms, etc. on the Internet. The ShareHolder infrastructure has several advantages. Its highly object-oriented view of shared variables simplifies their initialization and configuration. A shared variable's distribution mechanism is specified through an associated configuration object, and the programmer does not need to write any extra code to implement the sharing mechanism. These configuration objects can be initialized at run-time, allowing tremendous flexibility in dynamic control of distribution of shared variables. Finally, the programmer can easily evolve a serial application into a distributed application for cluster computing by incrementally declaring certain classes as shared.