The HTML/Java API is an alternative to Swing and JavaFX for creating applications with a graphical user interface. It's major strengths is the intelligent combination of existing technologies.
With HTML/Java, the proven model used on servers for many years, has been ported to the client. Java is used for developing business and view logic, while HTML5, CSS and JavaScript are used to render the UI. Get the best of both worlds by combining the industry stability of Java and richness of JavaScript ecosystem when it comes to UI and rendering frameworks.

### Motivation

The motivation for this project is the inability of Swing and JavaFX to keep up with the rapid development of browser based technologies, and the uncertain future of Swing and JavaFX. The logical solution is to simply use these technologies from Java instead of trying to build a whole own alternative stack. With Java/HTML we created a better and more powerful alternative, which is still small and easy to maintain.

### Model View ViewModel Pattern

For this Java/HTML makes use of the Model View ViewModel (MVVM) pattern to separate the view from the logic of the application. This approach is different from Swing or JavaFX, as the Java code doesn't require any references to the widgets that are displayed in the view. The Java code instead exposes {@link net.java.html.json.Property properties} for the View to bind to, and {@link net.java.html.json.Function functions} that can be called in response to user interactions. This keeps the {@link net.java.html.json.Model Java API} small and simple to learn.

### Supported Platforms

This architecture also makes it easy to port the technology to different platforms. Porting of HTML/Java is as easy as implementing {@link org.netbeans.html.boot.spi.Fn.Presenter} interface and successfully passing the {@link org.netbeans.html.json.tck test compatibility kit}. Various ports of this rendering pipeline were built including support for pure "webkit desktop rendring Android WebView and iOS WebView developed by DukeScript project.

This technology has also been adopted by some Java bytecode to JavaScript transpilers - for example TeaVM or Bck2Brwsr VM - as such you can also run the same Java application in a pluginless browser.

### Getting started

The easiest way to get started is following the getting started tutorial. If you prefer commandline you can also use the Maven Archetypes. Just type:

    $ mvn archetype:generate \
        -DarchetypeGroupId=com.dukescript.archetype \
        -DarchetypeArtifactId=knockout4j-archetype \
        -DgroupId=your.company -DartifactId=test -Dversion=1.0-SNAPSHOT
        -DarchetypeVersion=0.30 \ # or newer version, if available

and then you can:

    $ cd test
    $ mvn install
    $ mvn -f client/pom.xml process-classes exec:exec

### More Information

We tried to make our API Docs as useful as possible, so they contain lots of valuable information. So this should be your first stop when looking for information: Current development version

The DukeScript project contains a lot of information for Java/HTML developers. There's a Blog with the latest news and tips and tricks how to get the most out of these APIs and also an extensive getting started guide explaining all the concepts and walking you through code examples. For advanced users there's an in depth tutorial on the Knockout For Java API with many examples and tipps and tricks.

### Try it

And finally, if you want to see this API in action, look no further, here's an example application running with the Bck2Brwsr VM directly in your browser.

### New in version 1.8.1

This is a bugfix release focused on improving {@link org.netbeans.html.presenters.spi.ProtoPresenter} when running in {@linkplain org.netbeans.html.presenters.spi.ProtoPresenterBuilder#loadJavaScript(org.netbeans.html.presenters.spi.ProtoPresenterBuilder.Evaluator, boolean) asynchronous mode}. PR #48 changes the Knockout For Java binding to use JavaScript {@code Promise} to properly order initialization of many {@link net.java.html.json.Model} classes in a highly asynchronous environment. As a result the underlying JavaScript engine has to (since version 1.8.1) provide support for {@code Promise} or emulate it somehow.

### New in version 1.8

Asynchronous calls to Java - since PR #44 the {@link net.java.html.js.JavaScriptBody} annotation supports new {@link net.java.html.js.JavaScriptBody#wait4java wait4java=false} attribute. That allows one make an asynchronous call to Java. More information in the updated {@link net.java.html.js Java/JavaScript interactions} page. Support for reactive programming simplified with {@link net.java.html.json.Models#react} as provided by PR-43.

### New in version 1.7.3

Giving proper OSGi name to `org.netbeans.html.presenters.spi`, `org.netbeans.html.presenters.render`, `org.netbeans.html.presenters.browser` and `org.netbeans.html.presenters.webkit` modules - PR #40. Configure {@link org.netbeans.html.presenters.browser.Browser.Config#browser(java.util.function.Consumer) browser presenter} to handle opening of a {@code URI} programmatically - PR #42.

### New in version 1.7.2

Code completions for callbacks from JavaScript to Java - PR #36. Support for ecj - PR #37. Robustness of {@link org.netbeans.html.presenters.spi.ProtoPresenter} improved - PR #38.

### New in version 1.7.1

Bugfix release to address robustness and security issues.

### New in version 1.7

New modules are provided since PR #23:

- {@link org.netbeans.html.presenters.render render} - a way to start a browser - using native GTK (on Linux and Mac OS X), AWT or CLI
- {@link org.netbeans.html.presenters.spi.ProtoPresenterBuilder} - core implementation of a presenter that handles connection between JavaScript VM and Java VM via a textual protocol
- {@link org.netbeans.html.presenters.browser browser} - uses of {@link org.netbeans.html.presenters.spi.ProtoPresenterBuilder} to start a local server and let a browser connect to it
- {@link org.netbeans.html.presenters.webkit webkit} - native presenter for Linux and Mac OS X that uses WebKit via JNA

### What's new in older versions?

Click the link to view even more historic changes...

### New in version 1.6.1

One model instance can be used in two views (PR #14). GC related behavior has been improved (PR #19). Safe and {@link net.java.html.boot.script.Scripts sanitized builder} to create {@link javax.script.ScriptEngine}-based execution environment (PR #15). Switching to knockout.js version 3.5.0 (PR #20).

### New in version 1.6

Compiles on JDK11 while using Open JavaFX 11 when necessary. {@link net.java.html.json.ComputedProperty Computed properties} can depend on other computed properties - PR #3. {@link net.java.html.js.JavaScriptResource} annotation has been made repeatable - PR #4. `@Model` annotation processor bugfix #621.

### New in version 1.5.1

The project has been donated to Apache Foundation and the code is now hosted in the repository along other Apache incubating projects. Contribute to the project by forking its GitHub repository.

Using Android JSON parsing library as it is Apache licensed - bug #89. It is acceptable to read properties of a model when {@link net.java.html.json.ComputedProperty computing a property}. Regular subclassing of {@link org.netbeans.html.json.spi.Proto.Type} is possible. Bugfix #99 - better garbage collector related behavior of ko4j instances thanks to introduction of {@link org.netbeans.html.json.spi.Technology.ToJavaScript}. Mentioning knockout.js license in the ko4j artifact - bug #98. Simplifying dependencies of {@link org.netbeans.html.json.tck} - bug #111

Bug fix for multiple observers on a single model object. Better GC behavior specified in TCK and used in Knockout for Java implementation. Removing dependency on Java collection classes implementations. Adding {@link net.java.html.json.Models#asList} factory method to a create simple list implementation. Simplifying {@link org.netbeans.html.json.tck.KnockoutTCK} to avoid usage of {@link java.net.URI}, etc.

### New features in version 1.4

Both values `null` and `undefined` are treated as null. Better behavior under multi-threaded load. Workaround for garbage collector behavior of modern JavaFX WebView implementations (JDK8 u112 and newer). JavaFX Presenter can show popup window. Development has switched to Git repository thanks to conversion by Emilian Bold. Better support for obfuscation of knockout module (bug 270013).

### Improvements in version 1.3

{@link net.java.html.json.Model Model classes} can have {@link net.java.html.json.Model#instance() per-instance private data}. {@link net.java.html.json.Model Model classes} can generate builder-like construction methods if builder {@link net.java.html.json.Model#builder() prefix} is specified. {@link net.java.html.json.Property#mutable} can be `false` to define a non-mutable (almost constant) property. That in case of Knockout bindings means: the property is represented by a plain value rather than an observable in the JavaScript object. The JavaFX presenter can be executed in headless mode - just specify `-Dfxpresenter.headless=true` when launching its virtual machine and no window will be shown. This is particularly useful for testing. Configure your surefire or failsafe plugins like:

    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-surefire-plugin</artifactId>
      <version>2.13</version>
      <configuration>
          <systemPropertyVariables>
              <fxpresenter.headless>true</fxpresenter.headless>
          </systemPropertyVariables>
      </configuration>
    </plugin>

OSGi headers are now enterprise OSGi ready. Switched to minified version 3.4.0 of knockout.js. Better support for recursive @Model definitions. New module `org.netbeans.html:xhr4j` provides implementation of {@link org.netbeans.html.json.spi.Transfer} with {@link org.netbeans.html.context.spi.Contexts.Id technology identifier} xhr4j - this module can be used to workaround limitations of CORS by handling the {@link net.java.html.json.OnReceive} connections in Java.

### What's Been Improved in Version 1.2.3?

One can control {@link net.java.html.json.OnReceive#headers() HTTP request headers} when connecting to server using the {@link net.java.html.json.OnReceive} annotation. It is possible to have {@link net.java.html.json.ComputedProperty#write() writable computed properties}. There is an easy way to enable Firebug in the JavaFX based Web View - just run with `-Dfirebug.lite=true` as this video demonstrates. Bugfix of issues 250503, 252987.

### What's New in Version 1.1?

The content of a {@link net.java.html.BrwsrCtx context} can be selected by registering implementations under specific {@link org.netbeans.html.context.spi.Contexts.Id technology identifiers} and requesting them during {@link org.netbeans.html.context.spi.Contexts#newBuilder(java.lang.Object...) construction} of the context. `org.netbeans.html:ko4j` module's implementation offers ko4j, xhr and websocket identifiers for its registered services (e.g. {@link org.netbeans.html.json.spi.Technology}, {@link org.netbeans.html.json.spi.Transfer} and {@link org.netbeans.html.json.spi.WSTransfer}). `org.netbeans.html:ko-ws-tyrus` module registers its {@link org.netbeans.html.json.spi.Transfer Java based JSON} and {@link org.netbeans.html.json.spi.WSTransfer WebSocket} implementations under the name tyrus.

A particular DOM subtree that a knockout.js model gets applied to can be selected by using {@link net.java.html.json.Models#applyBindings(java.lang.Object,java.lang.String) Models.applyBindings(m, id)} with an id of an HTML element. There is new {@link net.java.html.json.Model#targetId()} attribute which controls behavior of the generated `applyBindings` method. If specified and non-empty, then the generated method will call {@link net.java.html.json.Models#applyBindings(java.lang.Object,java.lang.String)} with `this` and the provided {@link net.java.html.json.Model#targetId() target id}. If specified, but left empty, then the generated method calls {@link net.java.html.json.Models#applyBindings(java.lang.Object)}. If unspecified, the method will not be generated at all (a change with respect to older versions). However one can still use {@link net.java.html.json.Models#applyBindings(java.lang.Object)} or {@link net.java.html.json.Models#applyBindings(java.lang.Object,java.lang.String)} to perform the association of any model with the page element.

Memory model when using Knockout bindings has been improved (required additions of two new methods: {@link org.netbeans.html.json.spi.PropertyBinding#weak()} and {@link org.netbeans.html.json.spi.FunctionBinding#weak()}) and now the Java {@link net.java.html.json.Model models} can garbage collect, when no longer used. Library writers that use {@link net.java.html.js.JavaScriptBody} annotation can also control garbage collection behavior of method arguments by setting {@link net.java.html.js.JavaScriptBody#keepAlive() keepAlive=false} attribute.

### What's New in Version 1.0?

{@link net.java.html.json.Property#array() Array properties} are now mutable from the knockout.js point of view (required {@link org.netbeans.html.json.spi.Proto.Type#replaceValue one SPI change}). The page lookup mechanism can use {@link net.java.html.boot.BrowserBuilder#locale(java.util.Locale) locale} to load localized a page with appropriate suffix. All SPI were moved under the NetBeans namespace - e.g. {@link org.netbeans.html.boot.spi}, {@link org.netbeans.html.context.spi}, {@link org.netbeans.html.json.spi}, {@link org.netbeans.html.sound.spi}, and also {@link org.netbeans.html.json.tck}. Methods annotated with {@link net.java.html.js.JavaScriptBody} annotation and without fallback Java code now throw {@link java.lang.IllegalStateException} with a message suggesting to switch to proper {@link net.java.html.BrwsrCtx#execute browser context} to prevent endless debugging when one forgets to do so.

### What's New in Version 0.9?

System can run in {@link net.java.html.boot.BrowserBuilder#classloader(java.lang.ClassLoader) Felix OSGi container} (originally only Equinox). {@link net.java.html.json.ComputedProperty Derived properties} now deeply check changes in other {@link net.java.html.json.Model model classes} they depend on and recompute their values accordingly. Knockout.js library has been updated to version 3.2.0.

### What's New in 0.8.x Versions?

Setters or array properties on classes generated by {@link net.java.html.json.Model} annotation can be accessed from any thread. {@link org.netbeans.html.sound.spi.AudioEnvironment} can be registered into {@link net.java.html.BrwsrCtx}. There is a {@link net.java.html.json.Models#parse(net.java.html.BrwsrCtx, java.lang.Class, java.io.InputStream, java.util.Collection) method} to parse a JSON array and convert it into {@link net.java.html.json.Model model classes}. Improved behavior of `enum` values in {@link net.java.html.json.Model knockout bindings}.

Few bugfixes for better portability. New API for {@link net.java.html.boot.script.Scripts headless execution} on top of Nashorn - does not run knockout for Java fully yet (reported as JDK-8046013), however even in current state it is quite {@link net.java.html.boot.script.Scripts useful for testing} of {@link net.java.html.js Java/JavaScript interactions}.

{@link net.java.html.boot.fx.FXBrowsers} has been extended with new helper methods to make it easier to use HTML+Java API in existing JavaFX applications. The annotation processor is made more robust with respect to errors in callback syntax of {@link net.java.html.js.JavaScriptBody} body parameter. Javadoc of {@link net.java.html.BrwsrCtx#execute} method has been improved based on a failure of its usability study. There can be additional parameters to methods annotated by {@link net.java.html.json.OnReceive} that allows one to pass state when a JSON call is made and use it when it finishes. The mechanism of discovery of sibling HTML page has been extended to work on systems that don't support {@link java.lang.Class#getProtectionDomain}.

The first argument of method annotated by {@link net.java.html.json.OnReceive} annotation has to be the associated {@link net.java.html.json.Model model class}.

{@link net.java.html.json.OnReceive} annotation now accepts {@link java.util.List} of data values as second argument (previously required an array).

### What's New in 0.7.x Versions?

{@link net.java.html.js.JavaScriptBody} annotation has new attribute {@link net.java.html.js.JavaScriptBody#wait4js()} which allows asynchronous execution. Libraries using {@link net.java.html.js.JavaScriptBody} are urged to use this new attribute as much as possible, as it can speed up execution in certain environments.

Use {@link net.java.html.BrwsrCtx#execute(java.lang.Runnable)} in multi-threaded environment to execute your code on the browser thread. See example {@link net.java.html.BrwsrCtx#execute(java.lang.Runnable) using Java timer}.

## Other Resources

The javadoc for latest and previous versions is also available online:

- Current development version
- Version 1.7.1
- Version 1.7