Wednesday May 29, 2013

Repost: Taming the Nashorn (first impressions)...

[This is a repost of an article written by our friend @hansolo_ with his permission.  The original article is at  Taming the Nashorn (first impressions)...]

Hi there,

JavaScript is everywhere these days and so it is also part of JDK8 dev. prev. with Project Nashorn which is a lightweight high-performance JavaScript runtime engine.

Because I never used Rhino (which is in principle the same just older and slower) I had no  idea how to use it and for what reason.

After I met Marcus Lagergren (@lagergren) at JAX in Mainz (Germany), Geecon in Krakow (Poland) and at Java Forum in Malmö (Sweden) I decided that I have to take a look at the Nashorn to get an idea on how to use it. Of course I'm especially interested on how to use Nashorn in combination with JavaFX. Lucky me that Nashorn is part of the weekly developer previews of JDK8 since a few weeks ago and because Jim Laskey (@wickund) blogged about this use case I was able to start with it yesterday.

After some starting problems I slowly begin to understand and would like to share it with you...

First of all I would like to see how I could use Nashorn with JavaScript in combination with my controls, so the idea is to visualize a Lcd control of my Enzo library with Nashorn.

For the following example you'll need the jdk8 developer preview (grab it here) and a current version of my Enzo library (grab it here).

And with a shell and a text editor you are good to go...really nice :)

So first of all we need to create a JavaScript file that should create a JavaFX application which should show the Lcd control and set's the value of the Lcd control every 3 seconds to a random value between 0 and 100.

This is the JavaFX code to realize that...

import eu.hansolo.enzo.lcd.Lcd;
import eu.hansolo.enzo.lcd.LcdBuilder;
import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;
import java.util.Random;
public class EnzoFX extends Application {
  private Lcd            lcd;
  private Random         random;
  private long           lastTimerCall;
  private double         charge;
  private AnimationTimer timer;
  @Override public void init() {
    // Initialize the AnimationTimer
    random        = new Random();
    lastTimerCall = System.nanoTime();
    charge        = 0;
    timer         = new AnimationTimer() {
      @Override public void handle(long now) {
        if (now > lastTimerCall + 3_000_000_000l) {
          lcd.setValue(random.nextDouble() * 100);
          charge += 0.02;
          if (charge > 1.0) charge = 0.0;
          lastTimerCall = now;
    // Initialize the Enzo Lcd control
    lcd = LcdBuilder.create()
                    .title("Room Temp")
  @Override public void start(Stage stage) {
    // Prepare stage and add controls
    StackPane root = new StackPane();
    root.setPadding(new Insets(10, 10, 10, 10));
    stage.setTitle("Enzo in JavaFX");
    stage.setScene(new Scene(root, 528, 192));;
    // Start the timer
  public static void main(String[] args) {

Ok, so now we know how to achieve this in JavaFX but now let's take a look at the JavaScript code that leads to the same result. Here you go...

var System         = java.lang.System;
var Random         = java.util.Random;
var StackPane      = javafx.scene.layout.StackPane;
var Scene          = javafx.scene.Scene;
var Insets         = javafx.geometry.Insets;
var AnimationTimer = javafx.animation.AnimationTimer;
var Lcd            =;
// Initialize the AnimationTimer
var random        = new Random();
var lastTimerCall = System.nanoTime();
var charge        = 0;
var timer         = new AnimationTimer() {
    handle: function(now) {
        if (now > lastTimerCall + 3000000000) {
            lcd.value = random.nextDouble() * 100;
            lcd.trend = Lcd.Trend.values()[random.nextInt(5)];
            charge += 0.02;
            if (charge > 1.0) charge = 0.0;
            lcd.batteryCharge = charge;
            lastTimerCall = now;
// Initialize the Enzo Lcd control
var lcd   = new Lcd();
lcd.title                    = "Room Temp";
lcd.unit                     = "°C";
lcd.decimals                 = 2;
lcd.minMeasuredValueDecimals = 2;
lcd.maxMeasuredValueDecimals = 2;
lcd.unitVisible              = true;
lcd.batteryVisible           = true;
lcd.alarmVisible             = true;
lcd.minMeasuredValueVisible  = true;
lcd.maxMeasuredValueVisible  = true;
lcd.lowerRightTextVisible    = true;
lcd.formerValueVisible       = true;
lcd.trendVisible             = true;
lcd.lowerRightText           = "Info";
lcd.valueAnimationEnabled    = true;
lcd.foregroundShadowVisible  = true;
lcd.crystalOverlayVisible    = true;
// Prepare the stage and add controls
var root     = new StackPane();
root.padding = new Insets(10, 10, 10, 10);
$STAGE.title = "Enzo with Nashorn";
$STAGE.scene = new Scene(root, 528, 192);
// Start the timer

The JavaScript code that I saved to a file "javafx.js" looks not that different from the JavaFX code's JavaScript...and the resulting application will look like this...

You might ask yourself how you could run this code and here is the answer, all it takes is one call on the command line that looks like this:

-cp /PATH/TO/LIBRARY/Enzo.jar -fx /PATH/TO/JS-FILE/javafx.js

Means you have to now the path to your jdk8 installation folder where you could find the jjs executable that is needed to start nashorn from the command line. In addition you have to add the Enzo.jar to the classpath so that you could use it within your JavaScript file and at last you have to call the JavaScript file with the -fx parameter which will start the application....BAM...that's all...sweet :)

I've put the commandline in a bash script so that I could call it by simple calling the bash script instead of typing the whole line over and over again.

If you start the javafx.js file you should see something like on this youtube video.

Ok you might say where is the advantage of using JavaScript to run a JavaFX application...just think about not starting an IDE, not compiling and building a JavaFX application just to make a short test. Isn't it be much nicer to simply have a small JavaScript, edit it with your default text editor and run it with from the command line with one single call...I really like that for testing things.

If you would like to know more about Nashorn you should definitely take a look at the Nashorn blog ,subscribe to the Nashorn mailing list and take a look at the Nashorn Wiki.

At this point I would say THANK YOU to Jim Laskey and Marcus Lagergren which helped me to getting this stuff done!!!

This is really a first test of using Nashorn with JavaFX but now that I know how to use it I will use more stay tuned and keep coding...

Tuesday May 07, 2013

jjs -fx

So after some playing around and working with the JavaFX folks, I think we have a proposal for jjs that works with JavaFX.  The -fx flag on jjs will bootstrap scripts using a javafx.application.Application.  Thus, writing JavaFX scripts in Nashorn is very easy.

The basic command line is;
	jjs -fx fxscript.js
You can mix and match other jjs options like -scripting and -- ;
	jjs -fx -scripting fxscript.js -- my script args
The content of the script follows some of the examples I've posted before.  The script may optionally contain JavaFX init, start and/or stop functions.  What is new, is that you can leave them behind and just straight script.  The original hello world example;

var Button    = Java.type("javafx.scene.control.Button");
var StackPane = Java.type("javafx.scene.layout.StackPane");
var Scene     = Java.type("javafx.scene.Scene");

function start(stage) {
    stage.title = "Hello World!";
    var button = new Button();
    button.text = "Say 'Hello World'";
    button.onAction = function() print("Hello World!");
    var root = new StackPane();
    stage.scene = new Scene(root, 300, 250);;


var Button    = Java.type("javafx.scene.control.Button");
var StackPane = Java.type("javafx.scene.layout.StackPane");
var Scene     = Java.type("javafx.scene.Scene");

$STAGE.title = "Hello World!";
var button = new Button();
button.text = "Say 'Hello World'";
button.onAction = function() print("Hello World!");
var root = new StackPane();
$STAGE.scene = new Scene(root, 300, 250);

where the stage is now a global var $STAGE (instead of the start function argument.)

Also for convenience, we've predefined includes for all of the JavaFX classes.  I would recommend using only the classes you need (only needed for new and for static field access), but for prototyping having includes really helps things move along.

The hello world example can then be rewritten as;


$STAGE.title = "Hello World!";
var button = new Button();
button.text = "Say 'Hello World'";
button.onAction = function() print("Hello World!");
var root = new StackPane();
$STAGE.scene = new Scene(root, 300, 250);

The complete set of includes are as follows;









Here are a couple more examples;

// fx3d.js

var material = new PhongMaterial();
material.diffuseColor = Color.LIGHTGREEN;
material.specularColor = Color.rgb(30, 30, 30);

var meshView =[
    new Box(200, 200, 200),
    new Sphere(100),
    new Cylinder(100, 200)
], "javafx.scene.shape.Shape3D[]");

for (var i = 0; i != 3; i++) {
    meshView[i].material = material;
    meshView[i].translateX = (i + 1) * 220;
    meshView[i].translateY = 500;
    meshView[i].translateZ = 20;
    meshView[i].drawMode = DrawMode.FILL;
    meshView[i].cullFace = CullFace.BACK;

var pointLight = new PointLight(Color.WHITE);
pointLight.translateX = 800;
pointLight.translateY = -200;
pointLight.translateZ = -1000;

var root = new Group(meshView);

var scene = new Scene(root, 800, 800, true);
scene.fill = Color.rgb(127, 127, 127); = new PerspectiveCamera(false);
$STAGE.scene = scene;

// ColorfulCircles.js


var WIDTH = 500;
var HEIGHT = 600;
var animation;

function setup(primaryStage) {
    var root = new Group();
    primaryStage.resizable = false;
    var scene = new Scene(root, WIDTH, HEIGHT);
    scene.title = "Colourful Circles";
    primaryStage.scene = scene;
    // create first list of circles
    var layer1 = new Group();
    for(var i = 0; i < 15; i++) {
        var circle = new Circle(200, Color.web("white", 0.05));
        circle.strokeType = StrokeType.OUTSIDE;
        circle.stroke = Color.web("white", 0.2);
        circle.strokeWidth = 4;
    // create second list of circles
    var layer2 = new Group();
    for(var i = 0; i < 20; i++) {
        var circle = new Circle(70, Color.web("white", 0.05));
        circle.strokeType = StrokeType.OUTSIDE;
        circle.stroke = Color.web("white", 0.1);
        circle.strokeWidth = 2;
    // create third list of circles
    var layer3 = new Group();
    for(var i = 0; i < 10; i++) {
        var circle = new Circle(150, Color.web("white", 0.05));
        circle.strokeType = StrokeType.OUTSIDE;
        circle.stroke = Color.web("white", 0.16);
        circle.strokeWidth = 4;
    // Set a blur effect on each layer
    layer1.effect = new BoxBlur(30, 30, 3);
    layer2.effect = new BoxBlur(2, 2, 2);
    layer3.effect = new BoxBlur(10, 10, 3);
    // create a rectangle size of window with colored gradient
    var colors = new Rectangle(WIDTH, HEIGHT,
            new LinearGradient(0, 1, 1, 0, true, CycleMethod.NO_CYCLE,
                               new Stop(0,    Color.web("#f8bd55")),
                               new Stop(0.14, Color.web("#c0fe56")),
                               new Stop(0.28, Color.web("#5dfbc1")),
                               new Stop(0.43, Color.web("#64c2f8")),
                               new Stop(0.57, Color.web("#be4af7")),
                               new Stop(0.71, Color.web("#ed5fc2")),
                               new Stop(0.85, Color.web("#ef504c")),
                               new Stop(1,    Color.web("#f2660f"))));
    colors.blendMode = BlendMode.OVERLAY;
    // create main content
    var group = new Group(new Rectangle(WIDTH, HEIGHT, Color.BLACK),
    var clip = new Rectangle(WIDTH, HEIGHT);
    clip.smooth = false;
    group.clip = clip;
    // create list of all circles
    var allCircles = new java.util.ArrayList();
    // Create a animation to randomly move every circle in allCircles
    animation = new Timeline();
    for each (var circle in allCircles) {
              new KeyFrame(Duration.ZERO, // set start position at 0s
                           new KeyValue(circle.translateXProperty(), Math.random() * WIDTH),
                           new KeyValue(circle.translateYProperty(), Math.random() * HEIGHT)),
              new KeyFrame(new Duration(20000), // set end position at 20s
                           new KeyValue(circle.translateXProperty(), Math.random() * WIDTH),
                           new KeyValue(circle.translateYProperty(), Math.random() * HEIGHT))
    animation.autoReverse = true;
    animation.cycleCount = Animation.INDEFINITE;

function stop() {

function play() {;

function start(primaryStage) {

Playing ITunes from Nashorn

If you are on Mac OS X, it's possible to use Apple Script from Nashorn.  For example if you want to play a song in iTunes, the following script will do it;

#!/usr/bin/jjs -scripting
var song = "Bring It On Home";

$EXEC("/usr/bin/osascript", <<<EOD);
tell application "iTunes"
	play track "${song}" in playlist 1
end tell

HTTP Server Written In Nashorn

This is just a little "thinking outside the box" example.

Node.js is hot and anyone who has used it knows there is a ton of applications possible. Some of Node.js features remind me of a tool kit I had, when I worked for another server company prior to Oracle. All my development was remote and had to run on remote servers. I hate typing and ssh/console was my only way in. So, I decided that I would create a little HTTP server on the remote end, to proxy all my routine repository, build and file editing tasks via a browser. This didn't take a lot of effort and was very flexible.

There are many many HTTP server apps out there (many written in Java.) I could modify one of them, but I just wanted to prove to myself it could all be done in pure Nashorn. This is what I whipped up;

#!/usr/bin/jjs -scripting

var Thread            = java.lang.Thread;
var ServerSocket      =;
var PrintWriter       =;
var InputStreamReader =;
var BufferedReader    =;
var FileInputStream   =;
var ByteArray         = Java.type("byte[]");

var PORT = 8080;
var CRLF = "\r\n";
        <TITLE>404 Not Found</TITLE>
        <P>404 Not Found</P>

var serverSocket = new ServerSocket(PORT);

while (true) {
    var socket = serverSocket.accept();
    try {
        var thread = new Thread(function() { httpRequestHandler(socket); });
    } catch (e) {

function httpRequestHandler(socket) {
    var out       = socket.getOutputStream();
    var output    = new PrintWriter(out);
    var inReader  = new InputStreamReader(socket.getInputStream(), 'utf-8');
    var bufReader = new BufferedReader(inReader);
    var lines = readLines(bufReader);
    if (lines.length > 0) {
        var header = lines[0].split(/\b\s+/);

        if (header[0] == "GET") {
            var URI = header[1].split(/\?/);
            var path = String("./serverpages" + URI[0]);
            try {
                if (path.endsWith(".jjsp")) {
                    var body = load(path);
                    if (!body) throw "JJSP failed";
                    respond(output, "HTTP/1.0 200 OK", "text/html", body);
                } else {
                    sendFile(output, out, path);
            } catch (e) {
                respond(output, "HTTP/1.0 404 Not Found", "text/html", FOUROHFOUR);

function respond(output, status, type, body) {
    sendBytes(output, status + CRLF);
    sendBytes(output, "Server: Simple Nashorn HTTP Server" + CRLF);
    sendBytes(output, "Content-type: ${type}" + CRLF);
    sendBytes(output, "Content-Length: ${body.length}" + CRLF);
    sendBytes(output, CRLF);
    sendBytes(output, body);

function contentType(path) {
    if (path.endsWith(".htm") ||
        path.endsWith(".html")) {
      return "text/html";
    } else if (path.endsWith(".txt")) {
      return "text/text";
    } else if (path.endsWith(".jpg") ||
               path.endsWith(".jpeg")) {
      return "image/jpeg";
    } else if (path.endsWith(".gif")) {
      return "image/gif";
    } else {
      return "application/octet-stream";

function readLines(bufReader) {
    var lines = [];
    try {
        var line;
        while (line = bufReader.readLine()) {
    } catch (e) {
    return lines;

function sendBytes(output, line) {

function sendFile(output, out, path) {
    var file = new FileInputStream(path);

    var type = contentType(path);
    sendBytes(output, "HTTP/1.0 200 OK" + CRLF);
    sendBytes(output, "Server: Simple Nashorn HTTP Server" + CRLF);
    sendBytes(output, "Content-type: ${contentType(path)}" + CRLF);
    sendBytes(output, "Content-Length: ${file.available()}" + CRLF);
    sendBytes(output, CRLF);
    var buffer = new ByteArray(1024);
    var bytes = 0;
    while ((bytes = != -1) {
        out.write(buffer, 0, bytes);

Short and sweet, all done in 84 lines of JavaScript. I could have handled more of the http spec, but this will do as POC.

You can use this server to download html, jpeg et al, but in the midst of this server code you will see the following lines;

                if (path.endsWith(".jjsp")) {
                    var body = load(path);
                    if (!body) throw "JJSP failed";
                    respond(output, "HTTP/1.0 200 OK", "text/html", body);

This reads as, if the requested file ends with .jjsp, then evaluate the content as JavaScript and use the final result as an HTML response.

The following is a sample ".jjsp" file the I used for testing.

#!/usr/bin/jjs -scripting

var colours = {
    java: "BLUE",
    js: "RED", 
    css: "GREEN",
    html: "ORANGE"

function colorize(file) {
    var suffix = file.substr(file.lastIndexOf(".") + 1);
    var colour = colours[suffix];
    if (colour) {
        return "<FONT COLOR='${colour}'>${file}</FONT>";
    return file;

var files = `ls`.trim().split("\n");
files =;
files = "${file}<BR />");
files = files.join("\n");

var HTML = <<<EOD;
        <TITLE>Simple HTML</TITLE>
        <img width="256" height="138" src="rrr256x138.jpg" alt="rrr256x138" />
        <BR />
        <FONT FACE="Courier New" SIZE="2">


Note that both the JavaScript and HTML content of the .jjsp file is very easy to read.  This particular script catalogs a directory (ls) and colourizes the result depending on the file extension. In my case the result was;


Lots of possibilities.

Monday Apr 08, 2013

Keynoting at JAX2013

I have the honor to be keynoting JAX 2013 on April 25. The Keynote is called "Project Nashorn - and why dynamic languages on the JVM really matter". Exciting enough, surely, but it's not just "dynamic languages on the JVM", as it says in the title, that are becoming more and more important - I will show that it's really "languages on the JVM" that matters too, the JVM has its future as a polyglot runtime regardless of paradigm. Also, we are going to look at Project Nashorn as one good example of the future of the JVM.

There will also be a deep dive session about Nashorn during the conference, currently scheduled later the same day.

 The abstract is "More languages than Java have been implemented on top of the JVM since the very beginning in 1995. The platform independent bytecode format has always made it possible to compile anything and have it run on the JVM with the same write once/run anywhere benefits. Lately we are seeing an explosion in JVM languages. This is partly because of Java 7, which is the first giant leap in turning the JVM from a Java runtime to a true dynamic polyglot runtime. This keynote explains why language implementations, especially dynamic languages, are more feasible to implement on top of the JVM than ever and how the JVM can execute them with high performance. As an example, we will go into detail of the Nashorn project, Oracle's new JavaScript runtime, part of the JDK as of Java 8."

I'll see you there, and hopefully the spring weather in in Rhineland-Palatinate beats the spring weather in Stockholm. Probably not much of a competition, really.

Regards, Marcus 

Saturday Apr 06, 2013

To Shell Or Not To Shell

I find myself facing a dilemma today. How should I use Java FX from Nashorn? So far, I have two approaches I could use, but each comes with some issues. Some background first.

Java FX, even though ships with the JDK, is on a different build cycle and has dependencies on elements of the JDK. This arraignment limits Nashorn, which is part of the JDK, from actually having dependencies into Java FX. But, there is a dependency requirement to implement a Java FX application. Java FX applications begin with a subclass instance of javafx.application.Application. Therefore, whatever choice is made, it has to be independent of the JDK (at some point should be part of Java FX.)

The first approach, in general terms, is the easiest to use. It involves using a predefined shell that is similar to jjs but handles the overrides of Application methods init, start and finish. The source of this shell is currently checked into the Nashorn repo under nashorn/tools/fxshell.

 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit if you need additional information or have any
 * questions.
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.stage.Stage;
import javax.script.Invocable;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineFactory;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;
import jdk.nashorn.api.scripting.NashornScriptEngineFactory;
 * This shell is designed to launch a JavaFX application written in Nashorn JavaScript.
public class FXShell extends Application {
     * Script engine manager to search.
    private ScriptEngineManager manager;
     * Nashorn script engine factory.
    private NashornScriptEngineFactory factory;
     * Main instance of Nashorn script engine.
    private ScriptEngine engine;
     * Needed so that the FX launcher can create an instance of this class.
    public FXShell() {
     * Main entry point. Never actually used.
     * @param args Command line arguments.
    public static void main(String[] args) {
     * Application overrides.
    public void init() throws Exception {
        // Script engine manager to search.
        this.manager = new ScriptEngineManager();
        // Locate the Nashorn script engine factory.  Needed for passing arguments.
        for (ScriptEngineFactory engineFactory : this.manager.getEngineFactories()) {
             if (engineFactory.getEngineName().equals("Oracle Nashorn") &&
                 engineFactory instanceof NashornScriptEngineFactory) {
                this.factory = (NashornScriptEngineFactory)engineFactory;
        // If none located.
        if (this.factory == null) {
            System.err.println("Nashorn script engine not available");
        // Get the command line and JNLP parameters.
        final Parameters parameters = getParameters();
        // To collect the script paths and command line arguments.
        final List<String> paths = new ArrayList<>();
        final List<String> args = new ArrayList<>();
        // Pull out relevant JNLP named parameters.
        final Map<String, String> named = parameters.getNamed();
        for (Map.Entry<String, String> entry : named.entrySet()) {
            final String key = entry.getKey();
            final String value = entry.getValue();
            if ((key.equals("cp") || key.equals("classpath")) && value != null) {
            } else if (key.equals("source") && value != null &&
                       value.toLowerCase().endsWith(".js")) {
        // Pull out relevant command line arguments.
        boolean addNextArg = false;
        boolean addAllArgs = false;
        for (String parameter : parameters.getUnnamed()) {
            if (addAllArgs || addNextArg) {
                addNextArg = false;
            } else if (parameter.equals("--")) {
                addAllArgs = true;
            } else if (parameter.startsWith("-")) {
                addNextArg = parameter.equals("-cp") || parameter.equals("-classpath");
            } else if (parameter.toLowerCase().endsWith(".js")) {
        // Create a Nashorn script engine with specified arguments.
        engine = factory.getScriptEngine(args.toArray(new String[args.size()]));
        // Load initial scripts.
        for (String path : paths) {
        // Invoke users JavaScript init function if present.
        try {
            ((Invocable) engine).invokeFunction("init");
        } catch (NoSuchMethodException ex) {
            // Presence of init is optional.
    public void start(Stage stage) throws Exception {
        // Invoke users JavaScript start function if present.
        try {
            ((Invocable) engine).invokeFunction("start", stage);
        } catch (NoSuchMethodException ex) {
            // Presence of start is optional.
    public void stop() throws Exception {
        // Invoke users JavaScript stop function if present.
        try {
            ((Invocable) engine).invokeFunction("stop");
        } catch (NoSuchMethodException ex) {
            // Presence of stop is optional.
     * Load and evaluate the specified JavaScript file.
     * @param path Path to UTF-8 encoded JavaScript file.
     * @return Last evaluation result (discarded.)
    private Object load(String path) {
        try {
            FileInputStream file = new FileInputStream(path);
            InputStreamReader input = new InputStreamReader(file, "UTF-8");
            return engine.eval(input);
        } catch (FileNotFoundException | UnsupportedEncodingException | ScriptException ex) {
        return null;

To built it you can (cd make ; ant build-fxshell) from within the nashorn repo. The result is in nashorn/dist/nashornfx.jar. To use just java -cp dist/nashornfx.jar <myscript.js> … . For the JDK savvy you can create a launcher by modelling an entry in jdk/makefiles/CompileLaunchers.gmk after the jjs entry.

The big plus for this approach is that it handles almost everything for you. You just have to define a start method with a few class declarations and that is it. The down side is that ideally you would want this implemented as a jjsfx launcher embedded in the JDK. But then we run into the chicken and egg dependency on Java FX.

The second approach only relies on jjs. With a recent modification to Java.extend (currently only in the nashorn forest), it is now possible to subclass javafx.application.Application. and thus launch from within a script. This sounds like all pluses except for the fact you have to wrap your brain around the fact that FX applications take control of execution and has static init dependencies that require careful use in your program.

I prototyped a simple fxinit.js include that shows how we could implement such a scheme. Ignore the implementation quirks. It's simpler than it seems.

GLOBAL = this;
javafx = Packages.javafx;
(Java.extend(javafx.application.Application, {
    init: function() {
        // FX packages and classes must be defined here because they may not be
        // viable until launch time.
        Stage          = javafx.stage.Stage;
        scene          = javafx.scene;
        Scene          = scene.Scene;
        Group          = scene.Group;
        chart          = scene.chart;
        control        = scene.control;
        Button         = control.Button;
        StackPane      = scene.layout.StackPane;
        FXCollections  = javafx.collections.FXCollections;
        ObservableList = javafx.collections.ObservableList;
        Chart          = chart.Chart;
        CategoryAxis   = chart.CategoryAxis;
        NumberAxis     = chart.NumberAxis;
        BarChart       = chart.BarChart;
        XYChart        = chart.XYChart;
        Series         = chart.XYChart$Series;
        Data           = chart.XYChart$Data;
        TreeView       = control.TreeView;
        TreeItem       = control.TreeItem;
        if (GLOBAL.init) {
    start: function(stage) {
        if (GLOBAL.start) {
    stop: function() {
        if (GLOBAL.stop) {
})).class, new (Java.type("java.lang.String[]"))(0));

How you would use it is straight forward. Here is the FX example written for Nashorn;

function start(stage) {
    stage.title = "Hello World!";
    var button = new Button();
    button.text = "Say 'Hello World'";
    button.onAction = function() print("Hello World!");
    var root = new StackPane();
    stage.scene = new Scene(root, 300, 250);;
Note the placement of the load("fxinit.js");. Since this is where the FX Application takes control, anything after the load will not complete until the application exits.

One other quirk. Since you can not static init some of Java FX classes until after the application launches. You can not globally (script level) declare any uses of these classes. Uses can be embedded in methods used after the launch, but no where else. This is a style cramp for me.

There is a third approach I have been considering. It involves some argument trickery, but may play out as a better way of doing things. Imagine jjs fxinit.js -- myscript.js -- my scripts args . The -- indicates the beginning of arguments passed to the script. The notion here is that fxinit.js launches the application and then evals myscript.js. This cleanses my script of any quirks, while putting the onus on getting the command line right.


Wednesday Mar 20, 2013

Nashorn Events Coming Up

The team will be going to several events in the next few weeks.

Attila will be at Devoxx UK next week,  starting with a JUG Hackday on Sunday March 24, 2013 and presentation titled "Project Nashorn In Java 8 - JavaScript As A First Class Language On The JVM" on Wednesday March 27, 2012.

Jim (me) will be at EclipseCon 2013 for the Thursday March 28, 2013 keynote.

Tuesday Feb 12, 2013

ClojureScript REPL - If you build it, they will come!

Together with Attila Szegedi, also from the Java language team, I attended the very successful JFokus conference in Stockholm last week. I gave a talk about Nashorn and on implementing dynamic languages on the JVM in general. It seemed well received by the audience.

We also bumped into Bodil Stokke, of Catnip fame, there. Normally, as a Clojure open source developer, you just don't walk into the Oracle office, but we invited her over anyway and told the infrastructure orcs to stay under their desks. After depositing the ring she brought with her inside the big red volcano, we discussed Nashorn and other things for a bit.

A couple of days later, Bodil has made available an awesome ClojureScript REPL for Nashorn. Standard Clojure doesn't rely on invokedynamic for its implementation, but now can we can play with a ClojureScript that does. Neat.

 The javax.scripting API indeed enables some pretty powerful stuff.

Friday Feb 08, 2013

CSI: Nashorn - Shell Scripting in JavaScript, WAT?

I was reading the article in The Register with the heading GNOME project picks JavaScript as sole app dev language, when I remembered that we haven't said much about shell scripting using Nashorn.

This may seem sacrilegious to both JavaScripters and shell scripters, but think about it. The features that make JavaScript good for browser support are similar to what is needed for shell scripting. Plus you have access to all those Java libraries, and JavaFX, wink, wink, nudge, nudge (think visualization.)

There is an option (-scripting) in the Nashorn engine that extends the JavaScript language with features that make JavaScript very useful for writing shell scripts (even shebang scripts.) These features include;
  • function $EXEC("command args", "input"); that executes a command string as a separate process with handling of stdin, stdout $OUT, stderr $ERR and exit code $EXIT,
  • an exec string `command args` syntax for simple execution,
  • edit strings for embedding expressions in a double quote or exec strings, single quote strings are always unedited,
  • here strings, with editing for multi-line strings, <<TAG…TAG for include end of line and <<<TAG…TAG for exclude end of line,
  • environment variable $ENV for access to shell variables,
  • access to command line arguments with $ARG,
  • exit(code) and quit() for terminating the script,
  • and, # style comments
I will submit more scripting examples in the future, but let's start off with the following teaser.

Fingerprinting Source Code 

Often enough, when we are working on Nashorn, we run across some source that is unfamiliar and we would like to discuss the code with the original author. This is sometimes called blaming, but really, it's just about getting up to speed on the code without a lot of pain and suffering.  Nashorn is stored in a Mercurial repository on Mercurial already supports basic change set annotation of source, but sometimes you just want to cut to the chase and get the full details of a specific source line.

The following shell script, suspect, takes a root source file name and a line number, and then displays the change set information associated with the source line.

# This script hunts down the change set associated with a
# source file and a line number.

// Report proper command usage.
function usage() {
usage: suspect javaFileName lineNumber
    javaFileName - name of file in local mercurial repository
    lineNumber   - file line number

// Report on stderr.
function error(message) {

// Provide meaningful names for arguments.
var fileName   = $ARG[0];
var lineNumber = $ARG[1];

// If arguments are missing, report proper usage.
if (!fileName || !lineNumber) {

// Add .java if not present.
if (!fileName.endsWith(".java")) {
    fileName += ".java";

// Search for matching files and convert the result to an array of paths.
var where = `find . -name ${fileName}`.trim().split("\n");

// If not found
if (where == "") {
    error("File ${fileName} is not in the current repository.\n");
} else if (where.length != 1) {
    error("File ${fileName} found in multiple locations\n${where.join('\n')}\n");

// Get the source annotated with change set number.
var annotated = `hg annotate -c ${where}`.split("\n");

// Get the target source line.
var line = annotated[lineNumber];

// Make sure the line exists.
if (!line) {
    error("File ${fileName} does not contain line number ${lineNumber}\n");

// Extract the revision number.
var revision = line.substring(0, 12);

// Report the change set information from the revision number.
print(`hg log -r ${revision}`);

If I wanted to find out about the changed set for line 63 of,

>> suspect SpillProperty 63
changeset:   2:da1e581c933b
user:        jlaskey
date:        Fri Dec 21 16:36:24 2012 -0400
summary:     8005403: Open-source Nashorn

This is just the beginning.

Wednesday Jan 16, 2013

Implementing Dynamic Languages on the JVM

java.lang.invoke.* and the invokedynamic bytecode have given us a powerful new toolbox with which to implement dynamic languages on the JVM. At Devoxx in Antwerp last November, I gave a talk about how to build dynamic languages in Java7+, using the JVM as the runtime. While the talk is not necessarily implementation specific, a large part of the talk covered the Nashorn project. 

The fine folks at Devoxx now released my talk for free to the public, so if you are interested in the implementation details of a modern dynamic language running on the JVM, I encourage you to check it out. 

Link to talk: Nashorn - Implementing dynamic languages on the JVM

Friday Dec 21, 2012

Open For Business

After a lot of blood, sweat and tears, we finally got Nashorn into OpenJDK.

hg fclone nashorn~jdk8

or for just Nashorn

hg clone nashorn

 More details about the tools you'll need and using OpenJDK are at

This is just the first drop and needs some larger integration work, but you can browse the source, build and play.  Be sure to read the README and RELEASE_README,  If you have any questions or issues please send them along to .  Responses may be a little slow over the holidays, but we will respond.

Friday Dec 07, 2012

The Vote Is In

Just got the following e-mail.  Gonna be busy next week.

Voting on the Nashorn Project with initial Lead Jim Laskey [1] is


Yes:  20
Veto:  0
Abstain:  0

According to the Bylaws definition of Lazy Consensus, this is
sufficient to approve the new Project and its initial Lead.

-John Coomes


Saturday Dec 01, 2012

Nashorn in the Twitterverse, Continued

After doing the Twitter example, it seemed reasonable to try graphing the result with JavaFX.  At this time the Nashorn project doesn't have a JavaFX shell, so we have to go through some hoops to create an JavaFX application.  I thought showing you some of those hoops might give you some idea about what you can do mixing Nashorn and Java (we'll add a JavaFX shell to the todo list.)

First, let's look at the meat of the application.  Here is the repackaged version of the original twitter example.

var twitter4j      = Packages.twitter4j;
var TwitterFactory = twitter4j.TwitterFactory;
var Query          = twitter4j.Query;

function getTrendingData() {
    var twitter = new TwitterFactory().instance;
    var query   = new Query("nashorn OR nashornjs");
    query.count = 100;
    var data = {};

    do {
        var result =;
        var tweets = result.tweets;
        for each (var tweet in tweets) {
            var date = tweet.createdAt;
            var key = (1900 + date.year) + "/" +
                      (1 + date.month) + "/" +
            data[key] = (data[key] || 0) + 1;
    } while (query = result.nextQuery());

    return data;

Instead of just printing out tweets, getTrendingData tallies "tweets per date" during the sample period (since "2012-11-21", the date "New Project: Nashorn" was posted.)   getTrendingData then returns the resulting tally object.

Next, use JavaFX BarChart to display that data.

var javafx         = Packages.javafx;
var Stage          = javafx.stage.Stage
var Scene          = javafx.scene.Scene;
var Group          = javafx.scene.Group;
var Chart          = javafx.scene.chart.Chart;
var FXCollections  = javafx.collections.FXCollections;
var ObservableList = javafx.collections.ObservableList;
var CategoryAxis   = javafx.scene.chart.CategoryAxis;
var NumberAxis     = javafx.scene.chart.NumberAxis;
var BarChart       = javafx.scene.chart.BarChart;
var XYChart        = javafx.scene.chart.XYChart;
var Series         = javafx.scene.chart.XYChart.Series;
var Data           = javafx.scene.chart.XYChart.Data;

function graph(stage, data) {
    var root = new Group();
    stage.scene = new Scene(root);
    var dates = Object.keys(data);
    var xAxis = new CategoryAxis();
    xAxis.categories = FXCollections.observableArrayList(dates);
    var yAxis = new NumberAxis("Tweets", 0.0, 200.0, 50.0);
    var series = FXCollections.observableArrayList();
    for (var date in data) {
        series.add(new Data(date, data[date]));
    var tweets = new Series("Tweets", series);
    var barChartData = FXCollections.observableArrayList(tweets);
    var chart = new BarChart(xAxis, yAxis, barChartData, 25.0);

I should point out that there is a lot of subtlety in this sample.  For example;
stage.scene = new Scene(root) is equivalent to stage.setScene(new Scene(root)). If Nashorn can't find a property (scene), then it searches (via Dynalink) for the Java Beans equivalent (setScene.)  Also note, that Nashorn is magically handling the generic class FXCollections.  Finally,  with the call to observableArrayList(dates), Nashorn is automatically converting the JavaScript array dates to a Java collection.  It really is hard to identify which objects are JavaScript and which are Java.  Does it really matter?

Okay, with the meat out of the way, let's talk about the hoops.

When working with JavaFX, you start with a main subclass of javafx.application.Application.  This class handles the initialization of the JavaFX libraries and the event processing.  This is what I used for this example;

import javafx.application.Application;
import javafx.stage.Stage;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.ScriptException;

public class TrendingMain extends Application {

    private static final ScriptEngineManager
                                        MANAGER = new ScriptEngineManager();
    private final ScriptEngine engine = MANAGER.getEngineByName("nashorn");
    private Trending trending;

    public static void main(String[] args) {

    public void start(Stage stage) throws Exception {
        trending = (Trending) load("Trending.js");

    public void stop() throws Exception {

    private Object load(String script) throws IOException, ScriptException {
         try (final InputStream is = TrendingMain.class.getResourceAsStream(script)) {
            return engine.eval(new InputStreamReader(is, "utf-8"));
To initialize Nashorn, we use JSR-223's javax.script. 

private static final ScriptEngineManager MANAGER = new ScriptEngineManager();
private final ScriptEngine engine = MANAGER.getEngineByName("nashorn");

This code sets up an instance of the Nashorn engine for evaluating scripts.

The  load method reads a script into memory and then gets engine to eval that script.  Note, that load also returns the result of the eval.

Now for the fun part.  There are several different approaches we could use to communicate between the Java main and the script.  In this example we'll use a Java interface.  The JavaFX main needs to do at least start and stop, so the following will suffice as an interface;

public interface Trending {
    public void start(Stage stage) throws Exception;
    public void stop() throws Exception;

At the end of the example's script we add;

function newTrending() {
    return new Packages.Trending() {
        start: function(stage) {
            var data = getTrendingData();
            graph(stage, data);

        stop: function() {



which instantiates a new subclass instance of Trending and overrides the start and stop methods.  The result of this function call is what is returned to main via the eval.

trending = (Trending) load("Trending.js");

To recap, the script Trending.js contains functions getTrendingData, graph and newTrending, plus the call at the end to newTrending.  Back in the Java code, we cast the result of the eval (call to newTrending) to Trending, thus, we end up with an object that we can then use to call back into the script. 



Thursday Nov 29, 2012

Nashorn in the Twitterverse

I have been following how often Nashorn has been showing up on the net.  Nashorn got a burst of tweets when we announced Project Nashorn and I was curious how Nashorn was trending per day, maybe graph the result.  Counting tweets manually seemed mindless, so why not write a program to do the same.

This is where Nashorn + Java came shining through.  There is a very nice Java library out there called Twitter4J that handles all things Twitter.  After running bin/ to get a file with personal authorization, all I had to do to run my simple exploratory app was;

nashorn -cp $TWITTER4J/twitter4j-core-3.0.1.jar GetHomeTimeline.js

The content of GetHomeTimeline.js is as follows;

var twitter4j      = Packages.twitter4j;
var TwitterFactory = twitter4j.TwitterFactory;
var Query          = twitter4j.Query;

var twitter = new TwitterFactory().instance;
var query   = new Query("nashorn OR nashornjs");
query.count = 100;

do {
    var result =;
    var tweets = result.tweets;

    for each (tweet in tweets) {
        print("@" + tweet.user.screenName + "\t" + tweet.text);
} while (query = result.nextQuery());

How easy was that?  Now to hook it up to the JavaFX graphing library... 


Technical discussions and status of the Nashorn JavaScript Project.


« September 2015