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

NumberBox.ajava

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import javax.swing.*; public aclass NumberBox extends AComponent { protected JTextField textField; private boolean reset = false; private boolean donePoint = false; public final Event OnOperation = new Event(); public NumberBox() { super(new JTextField(15)); textField = (JTextField)(component); textField.setHorizontalAlignment(JTextField.RIGHT); textField.setText("0"); } // appends a character (digit, or point) // to the current numeral public react (char c) { // digit if (Character.isDigit(c)) { if (reset) { textField.setText("" + c); reset = false; } else if (textField.getText().equals("0")) { if (c != '0') textField.setText("" + c); } else { textField.setText(textField.getText() + "" + c); } } // decimal point else if (c == '.' && !donePoint) { textField.setText(textField.getText() + '.'); donePoint = true; } } // injects the current operand into the operation // and forwards it to the ALU public react (Calculator.Operation op) { // pass to ALU op.operand = Double.parseDouble(textField.getText()); OnOperation <-- op; } // sets the value, resulting from an ALU // operation public react (double v) { textField.setText(Double.toString(v)); reset = true; donePoint = false; } }