Synchronization and inheritance schemes for an actor-based object-oriented language

Abstract

The combination of concurrent and object-oriented programming produces a promising programming paradigm, called concurrent object-oriented programming, for various concurrent applications. Object-oriented programming languages based on the actor model are included in an exemplary class in the paradigm. However, the design of such an integrated language faces a serious problem that the synchronization scheme for concurrent programming may interfere with a key feature of object-oriented programming, inheritance. The problem is called the inheritance anomaly. The inheritance anomaly reduces the benefits of reusability which is one of the most valuable capability in object-oriented programming. This thesis discusses the incorporation of an inheritance scheme in an object-oriented language based on the actor model resolving the inheritance anomaly. For the purpose we firat analyze the inheritance anomaly in existing actor-based languages as well as in various concurrent object-based ones. We suggest criteria for analyzing the cause of the inheritance anomaly in a language and for designing the synchronization scheme of a new language which does not raise the inheritance anomaly. We consider the design of reusable abstractions for specifying the synchronization constraints of objects as a design requirement to resolve the inheritance anomaly. Second, we design a new synchronization scheme for an actor-based object-oriented language which does not cause an inheritance anomaly. The scheme uses the reusable abstraction called behavior abstraction for specifying nondeterminism control, originated fron ACT++. It addition, we design a reusable abstraction called replacement abstraction for specifying behavior replacements, which is a key synchronization constraints in the actor-based languages. That is, the synchronization constraints of an object is specified separately from methods and thus it reduces the potential of the inheritance anomaly. Since the behavior of an obj...