Modular Atomic Objects

Abstract

A worthwhile approach to achieve transaction atomicity within object‐based distributed systems is to confine concurrency control and recovery mechanisms within the shared objects themselves. Such objects, called atomic objects, enhance their modularity and can increase transaction concurrency. Nevertheless, when designed independently, atomic objects can be incompatible, and if combined, do not ensure transaction atomicity anymore. It has been shown that atomic objects can be incompatible when they assume different Global Serialization Protocols (GSPs). We deal with the incompatibility problem by introducing a property of atomic object specifications, named o‐atomicity, which is orthogonal to the GSP. Objects that guarantee this property achieve transaction atomicity, whatever the GSP may be. Such objects are compatible, not only with each others, but also with atomic objects that guarantee previously defined GSP‐dependent properties, i.e. static atomicity, dynamic atomicity or hybrid atomicity. This is very desirable since most of existing object‐based distributed systems rely on these properties. To show how o‐atomicity can be ensured, we propose a generic implementation within an object‐oriented framework, which we illustrate through a simple banking application.