Research Seminar - October 12, 2001

Abstract:

The Java Language Specification (JLS) and Virtual Machine Specification (JVMS) specify the rules governing the execution of Java programs. However, much information may appear in the application's design documents which cannot be expressed using only Java class-signatures and the rules describing JVM execution. The solution is to make Java class-signatures more expressive and strengthen the JVM's execution model so that, in combination, they more fully describe the static and dynamic constraints governing the execution of a Java class. Efforts towards this end are progressing on a number of fronts - the research described here focusses upon strengthening the JVM's execution model so that it is more difficult to introduce inconsistencies into an application's state. Stronger rules than those governing try statements or normal execution, forcing the encapsulated block of statements to either atomically succeed or atomically fail, remove one source of state inconsistencies. Both of these can be accomplished through the introduction of transactional characteristics to JVM execution. This paper proposes a set of amendments to the JLS and JVMS to render implementations of those specifications capable of supporting transactional execution. Permitting class-signatures to better support design-by-contract by conveying information which, in combination with these stronger rules, more thoroughly describes the program's design will reduce the obstacles impending effective re-use of Java classes.