Jato: a compact binary file format for Java class

Abstract

Java has been a very important programming language, especially with its cross-platform characteristics, but the CLASS file format defined in the Java Virtual Machine (JVM) specification contains many redundancies and replications of information. These redundancies most come from the "constant pool" of a CLASS file. We propose a compact binary file format, called Jato, and its associated archive format, called Jatar, for the Java system. Using these two formats, many of the redundancies can be removed. We didn't utilize any text compression technique in the proposed formats, so they do not sacrifice the loading speed and are thus very suitable for use in embedded environments. We've also implemented a class loader that is capable of loading the Jato files into a regular JVM. Using this approach, we show that the Jato file format is effective and promising, while still keeping the cross-platform features of Java.