Stacking them up: a comparison of virtual machines

A popular trend in current software technology is to gain program portability by compiling programs to an intermediate form based on an abstract machine definition. Such approaches date back at least to the 1970s, but have achieved new impetus based on the current popularity of the programming language Java. Implementations of language Java compile programs to bytecodes understood by the Java Virtual Machine (JVM). More recently Microsoft have released preliminary details of their ".NET" platform, which is based on an abstract machine superficially similar to the JVM. In each case program execution is normally mediated by a just in time compiler (JIT), although in principle interpretative execution is also possible. Although these two competing technologies share some common aims the objectives of the virtual machine designs are significantly different. In particular, the ease with which embedded systems might use small-footprint versions of these virtual machines depends on detailed properties of the machine definitions. In this study, a compiler was implemented which can produce output code that may be run on either the JVM or .NET platforms. The compiler is available in the public domain, and facilitates comparisons to be made both at compile time and at runtime.