ActiveJava

Copyright Tristan Aubrey-Jones May 2008.

Abstract: A project investigating and developing an implicitly concurrent programming language, based on a metaphor taken from the physical world is reported. Uses a programming paradigm where programs consist of systems of autonomous agents, or active objects which communicate via message passing. A language enhancing Java with actors and linear types is presented. Example programs are written, compiled, and executed to evaluate the usefulness of the language. The language found to provide a familiar notation for implicit parallelism, and a compelling new model for concurrency, combining the performance of shared variables with the elegance of message passing.

Introductory Slides (PDF), Report (PDF),
ActiveJava compiler prototype (ajavac), ActiveJava runtime library (ajava_lang).

Examples:

calc - pocket calculator actor program
dining - dining philosophers actor program (never deadlocks)
sort - parallel quicksort implementation ("SortBenchmark" sorts 10,000 random integers using actors, java threads, and sequentially and compares)
To compile examples use:
compile.bat ./calc
compile.bat ./sort
compile.bat ./dining
To run examples use:
run ./calc Main
run ./dining Main
run ./dining Main fast
run ./sort Main
run ./sort SortingBenchmark

Main.java

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import org.taj.ajava.lang.*; public class Main extends Actor implements Entrypoint { private Calculator calculator = new Calculator(); private void react_0(String[] args) { calculator.deliver(new AFrame.Show()); } public void deliver(String[] args) { bufferMessage(new org.taj.ajava.runtime.ActorMessage(args, 0)); } protected void react(String[] args) { react_0(args); } protected void processMessage(org.taj.ajava.runtime.ActorMessage msg) { switch (msg.reactorId) { case 0: { react_0(((String[])msg.payload)); return; } default: { super.processMessage(msg); return; } } } private Main() { } private static class SingletonHolder { private final static Main instance = new Main(); } public static Main getInstance() { return SingletonHolder.instance; } }