Add a comment

Dragome exists thanks to your donations

Help us continue to make it better


Open Source

Dragome Web SDK fork me on github!
Takes your Java code to the web
Download Dragome

What is Dragome?

Dragome is an open source tool for creating client side web applications in pure Java (JVM) language.
Based on bytecode to javascript compilation, you can execute applications written in Java directly on browsers.
You may use your favorite IDE, your favorite Java frameworks and tools because Dragome is totally transparent.

See it in action: how Eclipse and Chrome interact on debug mode and production mode.

Also take a look at these example applications

Why Dragome

  • Full Java stack web applications, code everything in Java (server side and client side). It will be transformed to javascript automatically.
  • Fast GUI development using components, builders and two-way databinding, using similar AngularJs concepts.
  • Debug mode for debugging in your favorite Java IDE.
  • No IDE plugins or browser plugins required.
  • Java 8 ready. Build your pages using lambda expressions, default methods, streams
  • You can use Dynamic Proxies and Java Reflection API
  • Get rid of callbacks hell: Make async calls with no callbacks! How? See Callback Evictor Tool!
  • Use continuation in your development: you can pause your resulting js program and continue it whenever you need.
  • Unit testing integration: you can also run your Junit tests on a browser.
  • Javascript native interface for low level component construction.
  • Very powerful template engine. No logic in HTML files, only ids for locating templates placeholders.
  • … more at Features

Also see Dragome Todos for more info about the future

Dragome SDK modules

Dragome SDK can be divided into following six major parts:

  • Bytecode to JavaScript compiler : Dragome compiler is used to translate all the application code written in Java into JavaScript. Within compilation process there is a bytecode instrumentation chain that could be configured to add your custom manipulations. Examples of this configuration are CallbackEvictor and MethodLogger plugins, which add javaflow enhancer and custom ASM enhancer to achieve each functionality.
  • JRE Emulation library : Dragome includes a library that emulates a subset of the Java runtime library. Including metaprogramming tools such as reflection and dynamic proxies.
  • GUI Toolkit: The toolkit contains a set of visual basic components such as: Button, Label, Checkbox, Radiobutton, List, Combo, Panel, etc. These components works together with a template engine capable of locating them into HTML logicless templates. Components and template engine are totally decoupled from HTML and css, allowing the addition of other UI targets such as Android, IOS, wxWidgets, etc in a near future.
  • Form Bindings: Based on gwt-pectin project this module provides easy data bindings capabilities. It uses a declarative style API (guice style) for defining the models, commands and forms as well as binding them to components. In addition to gwt-pectin classes there is a small layer named “component builder” that helps to create components and binding with less effort.
  • Callback evictor: In charge of getting rid of callback hell, it uses bytecode instrumentation and dynamic proxies to do it.
  • Method logger: Simple method interceptor for automatic model changes detection, it also make use of bytecode instrumentations. It's commonly used by component builder layer to detects model changes in two-ways databinding.

Execution modes

Dragome provides two execution modes, production mode for executing everything in client side, and debug mode that executes all in Java Virtual Machine without compiling to javascript and make remotes updates to browser DOM.

SDKs comparison

Features Dragome GWT
Generates js from bytecode (produced by several JVM languages) java source code
Requirements for debug Any modern browser, no plugin required for IDE or browser IDE plugin and Browser plugin, not available for all browsers
JDK changes impact Almost no impact because bytecode rarely changes Big impact in every new JDK version because java syntax changes frequently
Incremental compiler yes -
Java 8 Lambda expressions, Stream API, default methods, and static interface methods available not supported
Continuation yes (through javaflow) -
Reflection yes -
Dynamic Proxies yes -
Bytecode instrumentation yes -
DOM level debug yes -
Code permutations - yes
Split compiling - yes
Template Engine yes -
Two-way databinding for UI yes -
Make async calls with no callbacks yes -

Start working with Dragome

Using maven archetype

mvn archetype:generate -DarchetypeGroupId=com.dragome -DarchetypeArtifactId=simple-webapp-archetype -DarchetypeVersion=1.0 -DgroupId={your-package-name} -DartifactId={your-app-name}

Using maven dependency in your project


Clone and build

How to build the SDK

Setup example application

Setup your application

How is programming web apps with Dragome?

pure Java, pure HTML, runs as js inside browser!

Debug your application in Java with your favorite IDE

Want to contribute?

  • Fork the project on Github.
  • Create an issue or fix one from the issues list.
  • Share your ideas or ask questions on mailing list - don't hesitate to write a reply - that helps us improve javadocs/FAQ.
  • If you miss a particular feature - browse or ask on the mailing list - don't hesitate to write a reply, show us a sample code and describe the problem.
  • Write a blog post about how you use or extend Dragome.
  • Please suggest changes to javadoc/exception messages when you find something unclear.
  • If you have problems with documentation, find it non intuitive or hard to follow - let us know about it, we'll try to make it better according to your suggestions. Any constructive critique is greatly appreciated. Don't forget that this is an open source project developed and documented in spare time.

Take a look at the following source code:

This is the complete source code for a simple hello world application using a service.

For more details see Hello World Application

Service definition

public interface HelloWorldService
    public abstract String getGreetingsFor(String name);

Service implementation

public class HelloWolrdServiceImpl implements HelloWorldService
    public String getGreetingsFor(String name)
        return "Hello " + name + "! (" + new Date() + ")";

Service consumer - GUI

public class HelloWorldPage extends DragomeVisualActivity
    HelloWorldService helloWorldService= serviceFactory.createSyncService(HelloWorldService.class);

    public void build()
        final VisualLabel<String> label= new VisualLabelImpl<String>("message");
        final VisualButton button= new VisualButtonImpl("button", v -> label.setValue(helloWorldService.getGreetingsFor("World")));


<script type="text/javascript" src="dragome/dragome.js"></script>

    Message: <b data-template="message">text</b> <br>
    <button data-template="button">Say hello!</button>