Modular Design for the Java Virtual Machine Architecture

We provide a modular high-level definition of the Java Virtual Machine (JVM) architecture. We decompose the machine into three components — the loader, the bytecode verifier and the interpreter — each for a hierarchy of four stepwise refined JVM program layers. These layers naturally correspond to the structuring of Java into sub languages with imperative, procedural, object-oriented and exception handling features. We give our definitions in terms of Abstract State Machines, which have a simple but precise semantic foundation. As a consequence our JVM models can be verified and validated by machine supported mathematical analysis and standard simulation techniques. Furthermore, due to their abstract nature, the models can serve as a platform independent basis for the evaluation and comparison of different JVM implementations.