Java, the new object-oriented programming language from Sun Microsystems, appears to be setting the standard for universal software development. Java code compiles into a binary format called bytecode which can be used for software distribution, and which does not need recompilation in order to run on any platform. Java is also secure, guarding against code corruption before execution. This new language uses run-time resolution to locate objects and their corresponding classes, meaning software updates can be integrated as quickly as they are made available. However, there are several trade-offs and costs involved in migrating to a universal software distribution environment.

Currently there are four approaches to running Java: an interpreter, a Just-In-Time (JIT) compiler, a Native Executable Translation (NET) compiler, and a hardware implementation. In this article we present our initial prototyping experience with our NET compiler, an optimizing Java-bytecode-to-native-machine-code translator. The objective of this work is to run the translated code at nearly the full performance of native code directly generated from a source representation such as the C/C++ programming languages. However, the work with our NET compiler is not limited to Java. Our goal is to develop a strong portfolio of techniques from our Java implementation efforts that will contribute to the development and acceptance of any universal software distribution language.

We focus our discussion on the critical issues involved in the design of our NET compiler, including minimizing verification overhead, mapping the stack computation model of the bytecode virtual machine to the register computation model of modern processors and developing a more efficient memory organization. We also explain some of the less intuitive costs involved in running Java. Preliminary results show that our optimizing NET compiler is currently capable of achieving better performance than the other bytecode execution methods, in some cases achieving speeds comparable to directly compiled native code.