A new compression scheme for syntactically structured messages (programs) and its application to Java and the Internet

Abstract

Summary form only given. The immense demand of required network bandwidth to load computer programs like Java applets or applications within an acceptable time makes efficient compression schemes highly desirable. Syntax-oriented coding (SOC) is a new compression scheme that is able to eliminate redundancy caused by syntactical restrictions. Current compression schemes with a lexical view of the source cannot efficiently exploit knowledge of these restrictions. The paper illustrates the current state in transmitting Java applets (compiled bytecode) over the net, as well as the integration of SOC into this framework. The smart and seamless integration of SOC in the existing Java architecture is obvious. In the compression performance of SOC, the paper depicts the file sizes of various representations of a typical Java applet: the size (containing no comments) of the (ASCII-) source code, the size of the class file (bytecode), the size of the compressed (Ziv-Lempel coding) class file and the size of the SOC-code. Using SOC a compression ratio of more than 6 is obtained compared to the Java class file, and even if the class file is Ziv-Lempel coded a ratio of more than 4 is still reached, reducing required bandwidth by 75 percent.