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GWT wrappers around the OZONE Widget Framework (OWF) library
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OWF-GWT implements Java-based Google Web Toolkit (GWT) wrappers around the OZONE Widget Framework (OWF) library. A developer building a GWT application can use OWF-GWT to much more easily add their GWT widgets into an OWF environment, using Java APIs and Java IDE's to extend their app with OWF pub/sub channels, proxy methods, and intents, as well as automatic widget launching and other features that help expose the app as a firt class OWF widget.

Tools have also been incorporated to simplify widget deployment to multiple OWF instances. And OWF-GWT includes a very useful and fully-implemented option to expose a collection of widgets outside of an OWF environment (as a standalone application with a collection of widgets), without losing any of the implemented IWC capabilities.


Besides GWT itself, OWF-GWT depends on the JsFunction-GWT project, also on GitHub, and was partially modeled after the GWT/JS integration done for Cesium-GWT.


My first significant GWT application ("SAPPHIRE") was a stand-alone, single GWT app based on Sencha GXT. It had separate "views" and "forms" in various tabs and layouts, and each tabbed component could call any other component via direct Java (GWT) method calls. This was very convenient, but did not support loading these components as separable widgets into the DoD-preferred OZONE Widget Framework (OWF).


OWF-GWT's owf-gwt-test module demonstrates how to create GWT widgets that work in a standalone GWT app (the EntryPoint widget in, with matching GWT module descriptor owfgwttest.gwt.xml) as well as work as individual, independent widgets in an OWF framework.

Browse along with and to see how the individual widgets are loaded directly into a standalone GWT app.

The rest of this README file explains how these widgets are also prepared for and deployed to an OWF environment.

Steps to Convert GWT Widgets to OWF Widgets

To solve the problem, I had to make each component a separable GWT module. This entails the following:

  1. Implement the GWT EntryPoint interface in the component.

    • In a typical GWT application, each component is either a Widget or an "IsWidget" (IsWidget is an interface with the method "asWidget()" that allows the widget initialization to be deferred until the actual Widget is needed--e.g., to load it into a container.)

    • EntryPoint requires one additional method: "onModuleLoad()". This is a good place to perform any standard configuration, including loading any configuration information, for example. The one thing normally required in a GWT app is to load the primary UI (typically "this" widget) into the RootPanel (the main window or--in the case of OWF--the widget frame):

        public void onModuleLoad() {
  2. Create the GWT module descriptor for each component that will now be an individual OWF widget. In order to take advantage of OWF-GWT's deployment tools, the GWT module descriptor must be named the widget class name with ".gwt.xml" extension, e.g., would have the descriptor:


    Copy one of the existing module descriptors and change "<module rename-to=" to match the module name in the of the descriptor file; add or remove inherits (note it's possible that you may not realize you need some of these--comment out ones you THINK you don't need, so you can easily add them back); and change the "<entry-point" to the EntryPoint class in step 1.

  3. Update the Run Configurations for the SuperDevMode and the DevMode servers. Both of these Run Configurations contain arguments that refer to every possible GWT module.

    DevMode's final arguments are a space-separated list of dot-delimited module names to load, of the form "com.harmonia.sapphire.mywidget" (referring to the location and name of the GWT module file, without the ".gwt.xml" suffix). DevMode's list SHOULD get updated automatically, when you open the RunConfiguration, because the standard DevMode run configuration editor automatically searches for available modules in the source path, like the one you just created in step 2.

    SuperDevMode (aka CodeServer) requires a -src parameter for each module, with two following arguments: the path to the Java source and the dot-delimited module, just like what was provided in the DevMode arguments. It's likely there is a valid relative path to use, but I have used the practice of providing a fully-qualified path, e.g.:

     -src /Users/richkadel/work/harmonia/sapphire/harmonia-sapphire-apps/src/main/java com.harmonia.sapphire.mywidget

    You may want to figure out the starting location and use a relative path; but certainly remove and/or replace the specific user account "/Users/richkadel" and any leading path components (like "work"), and set the module location/name appropriately

  4. Go back into the EntryPoint class you are modifying, and enable it for OWF. One requirement of ALL EntryPoint classes is that it have a no-arg constructor. Most SAPPHIRE apps require two constructors: the no-arg constructor used when called from GWT as an EntryPoint, and a constructor that takes a WidgetHandle, passed in directly from a class that implements WidgetContainer. The original SAPPHIRE GUI has two TabbedWidgetContainers (one for views and one for forms).

    Standard SAPPHIRE best practice for OWF and direct widget constructors is as follows:

     public SPARQLForm() {// entry point constructor
     public SPARQLForm(WidgetContainer widgetContainer) {
       widgetHandle = WidgetFramework.createWidgetHandle(widgetContainer, this);
       // do not use until Widget.onLoad() or IsWidget.asWidget() are called

    The TreeView class is the exception. It is not held in a WidgetContainer so there is only the no-arg constructor, and the WidgetContainer parameter in the createWidgetHandle method is passed in as "null".

  5. If your Widget is a subclass of a GWT Widget, you should override the Widget.onLoad() method to complete your initialization. But if your widget class implements "IsWidget", you will likely initialize the widget in the "asWidget()" method (with a check to ensure your initialization only happens one time, since asWidget() can be called multiple times and subsequent calls should simply return the main widget created during the first invocation). Wherever you do the initialization, you will need to add OWF-style widget initializations including a declaration of received "Intent"s, subscribed "EventingChannel"s, and registered "WidgetFunctionProxy"s.

    Here's a typical call sequence at the end of the widget initialization, which starts "listening" for widget intents for FolderItem's having been selected or double-clicked. At the end, call widgetHandle.notifyWidgetReady() to let other widget's know the widget is ready to receive events:

     new FolderItemSelected(widgetHandle, MapView.CONFIG_TYPE_SUFFIX) {
       public void intentReceived(WidgetProxy sender, FolderItemMetaData data) {
     new FolderItemDoubleClicked(widgetHandle, MapView.CONFIG_TYPE_SUFFIX) {
       public void intentReceived(WidgetProxy sender, FolderItemMetaData data) {
     new PointsToMap(widgetHandle) {
       public void intentReceived(WidgetProxy sender, JsMetaTable jsMetaTable) {
         MetaTable metaTable = new JsMetaTableHolder(jsMetaTable);
     WidgetProxyFunctions wpf = new WidgetProxyFunctions();
     wpf.add(MapViewProxy.MORPH_TO_2D, new NoArgsFunction() {
       public void callback() {
     wpf.add(MapViewProxy.MORPH_TO_3D, new NoArgsFunction() {
       public void callback() {
         new NoArgsFunctionJsReturn<MapViewSettings>() {
           public MapViewSettings callback() {
             return MapViewSettings.create(getBaseLayer().getSaturation(),
                 getBaseLayer().getBrightness(), getCesiumWidget().getScene()
     new TreeViewChannel(widgetHandle) {
       public void onRequestFolderDetails(WidgetProxy tree) {
         AddSaveableView.startActivity(widgetHandle, saveableView);
  6. If your Widget sends any intents, or uses another form of inter-widget communication (WidgetProxy methods or Channel pub/sub), you will want to add those calls. If converting a GWT app from direct calls, remove all of the direct references to objects that are no longer part of your OWF widget (e.g., other widgets, or containers that will be removed in lieu of the OWF environment) and replace those calls with Intents or Channel messages, or WidgetProxy calls. (WidgetProxy calls require a WidgetProxy, which is typically obtained by coordinating with another widget through Intents or a Channel pub/sub message first.)

  7. Create the initial widget descriptor file. You can actually initialize a widget within OWF using the Widget Editor, but it is much easier to deploy a widget into OWF through a pre-existing widget descriptor file. The owf-gwt-test module includes some samples you can start from (copy and modify to suit):


    Copy one, and ensure you update:

    • universalName
    • widgetUrl (note the use of the URL fragment so a single HTML file can support multiple SAPPHIRE widgets)
    • imageUrlLarge - Create a 128x128 pixel image unique to your widget
    • imageUrlSmall - The large 128x128 images actually scale well in OWF, so you can typically use the same image for both large and small
    • displayName
    • intents, receive array - See the examples, and match the Intents subclasses you are receiving in your Widget initialization

    At this time, it appears there is no strong reason to declare the Intents a widget "sends".

    OWF-GWT provides a mechanism to easily create all of the widget descriptors automatically, and to re-generate widget descriptors for different environments and for different modes (production versus debug, with and without support for GWT Super Dev Mode). As long as you have implemented a standalone (non-OWF, aka "direct" mode) implementation of your complete app (e.g., you are instantiating all widgets at once, in a pre-existing GWT widget layout with or without WidgetContainer implementations like Dock, ViewTabs, and FormTabs), you can have OWF-GWT generate a script that you can invoke to generate descriptors. Run your app to launch all of the widgets outside OWF, and then open the browser's JavaScriptConsole to manually invoke the global method:

     > __OwfGwtSaveDescriptors()

    (Google Chrome and other modern browsers allow this kind of dynamic global function invocation.)

    After successful execution, the console will show the following message:

     "Your browser should be downloading a script that will create OWF widget 
     descriptor files for all widgets active in this DirectWidgetFramework.
     Execute this script from a Unix terminal, to save the widgets to /tmp/widgetdescriptors,
     then move them to an accessible URL (e.g., into your WAR file).
     Make the file executable or "bash" 
     (With no arguments, the script will print usage details and examples.)
     You may also want to save this script in your software code repository to
     create new widget descriptors for new environments you may need to deploy
     to in the future."

    And your browser will either automatically start or prompt for you to start downloading a generated bash script file you can execute to generate a complete set of widget descriptors along with all declared received intents.

    Note, __OwfGwtSaveDescriptors() can take two parameters:

    • "displayGroupName" - (typically your overall system/application name or company, such as "Harmonia") used to set the OWF widget's display name (used in a widget title bar) to include the group, distinguishing a set of widgets

    • "prefix" - used to add a prefix to the widget's name and universalName so you can create two versions of a widget in the same OWF (typically with different widget descriptor configurations, e.g., different launch parameters--e.g., one for production mode testing and one for debugging).

    After downloading the script to a suitable location (you may want to check it into your sourcecode baseline for easy access and reuse for new deployment environments), you can run the script through bash or change it's permissions to make the script executable (e.g., chmod 744

    Execute this script without parameters to see the parameter options and examples. When created (by passing in the required parameters), the widget descriptors and a couple of useful files (paths.txt and intentsMap.txt--see below for more information on each of these files) are written to /tmp/widgetdescriptors (replacing any previous versions in that directory). All of these files can be copied to a path inside your webapp, e.g., src/main/webapp/testwidgets/

  8. In OWF, using an OWF admin account (like testAdmin1, if using the default development setup), open the "Widgets" widget from the widget tools button. Select the "Create" button and enter the URL of the descriptor file previously created above. If successfully loaded, press the "Apply" button. If the "wait" icon spins, either the URL is wrong or you might have forgotten to restart the "DevMode" server to recognize the new descriptor file, or to "Refresh" the Package Explorer to make sure Eclipse sees the files added to the webapps directory, before restarting DevMode. Hit "Cancel" and try to correct the issue.

    Note the __OwfGwtSaveDescriptors() script creates a "paths.txt" file listing all of the widget descriptor paths for your convenience. You can quickly copy and paste these paths into successive instances of the Widget Editor as you load each one.

  9. Before closing the "Widget Editor", select "Users" (and/or "Groups") and add any users that need access to this widget. Close the "Widget Editor" and "Widget" widget. Reload OWF (often, the new widget will not show up automatically, and may also suppress other widgets). Or it can be faster to open the "Users" editor and add all new widgets to a given user at one time. Then try to add your new widget to your OWF desktop.

    If you are using Intents, you will be prompted for the widget to receive an intent, at the time it is used. Click the checkbox to remember each selection, and you won't be prompted for that intent again. If you have a problem with an intent (either not being sent or not received), close the affected widget(s) and reopen them. This will start the intent selection process again.

    Note the __OwfGwtSaveDescriptors() script creates an "intentsMap.txt" file that lists all intents with only one recipient, and the unique widget universal name that receives that intent. When you run the "" script, you can specify a parameter to use this intents map, which avoids prompting the user to specify the destination widget when there is only one. (The side effect is, only one instance of the destination can be used.)

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