Using a new plug-in module to create, build, deploy and debug extensions and client applications


Automating office tasks, implementing document-based workflows or building corporate solutions are common tasks that can benefit from using the API of an Office suite. with its millions of users, and Java with its huge community have several similarities; both, for example, are multiplatform and open source. But a tool to combine both worlds was missing. That’s where the new plugin module for NetBeans comes into the game.

In this article we will show you how to use the new module to build Java components which extend’s general functionality; we also create a new Calc function and a client application that accesses OOo features. (StarOffice won’t be mentioned explicitly in the article, but everything shown here works for StarOffice as well.)


The plugin module for NetBeans provides four wizards which let you create general Add-Ons, Calc Add-ins, Components and Client Applications:

§ An Add-On is widely available and not limited to a certain document type. It can also implement its own toolbars and menus. Add-ons are typically used for implementing new features that are directly accessible to users.

§ A Calc Add-In implements a new Calc function for the Function Autopilot in spreadsheet documents. A Calc function requires a different set of attributes than those covered by the general Add-On wizard – like function parameter definitions.

§ Components can be used to extend the API and be accessed through scripting languages. Components can also extend OOo’s charting functionality.

§ Finally, external Client Applications can use’s functionality to create, convert, print or manipulate documents. Thus, can be used as powerful rendering and printing engine within a larger solution.


The new wizards create NetBeans projects with all necessary configurations, such as links to the Java libraries. They also define build targets, perform remote debugging setup and generate Java code skeletons, among other operations.

Requirements, installation and configuration

To use the NetBeans OOo plugin module you need NetBeans 5.5 or newer, and either 2.0.4 or StarOffice 8 PU4; also needed is the SDK 2.0.4 or newer.

The wizards are provided in a common NetBeans module that can be installed and updated via the Update Center. Just download the file
and use Run>Update Center>Install Manually Downloaded Modules (.nbm Files)1.

Setup is straightforward. There are just two configuration items available: the paths to the installation and to the SDK. These are accessible during installation and also via the Tools>Options>Miscellaneous dialog.


1 By the time you read this, it’s possible that the module will show up in the Update Center, making the manual download unnecessary.

Creating OOo extensions

All four extension types are packed as OOo packages. This package format was introduced in 2.0.4 and uses the file extension .OXT. A corresponding MIME type is registered in, which enables users to install extensions simply by double clicking.


The File>New Project dialog provides a new category that opens the Add-On wizard. Start the wizard, and enter “myAddOn” for both the project and add-on names. Set the Java package to “org.openoffice”; provide the project folder, and check the Create Menu and Create Toolbar checkboxes.

Click Next and you’ll be able to specify the add-on commands. Each command can have an icon assigned to it on the toolbar. Ideally, you should provide four different icons (two different sizes in two contrast levels), but it’s possible to use the same image for all icon types. If you do this will scale the image accordingly.

You also need to enter a display name for the command. This name is used for the menu and toolbars and can be different from the command name. Note that only the display name can be translated: the wizard lets you define different locales, but the command name is the same for all locales.

In the next step you define the menu structure. This is optional, as not all add-ons have their own menus. Figure 1shows the menu definition wizard page. 

Figure 1. Defining the add-on’s menu structure.

The next step is also optional: the definition of a toolbar to call the add-on’s commands (see Figure 2). The icons in the toolbar preview should look familiar, as they were specified in step three. Set the names as “myAddOn”, define the icons and set the category. 

Figure 2. Defining the toolbar for the add-on.

After you click Finish, the wizard creates two configuration files and a Java class skeleton. The AddOns.xcu configuration file includes the add-on parameters, and ProtocolHandler.xcu defines the protocol handler configuration. Protocol handlers are part of dispatch framework; they bind user-interface controls, such as menu or toolbar items, to the functionality of Everything reachable through the user interface is described by a command URL and corresponding parameters.

The structure of the ProtocolHandler.xcu file defines a namespace for the add-on (org.openoffice.myaddon, for our example). All commands defined by the same add-on use this namespace. See Listing 1.

Listing 1. Excerpt from the ProtocolHandler.xcu configuration file.

<node oor:name=”HandlerSet”>
<node oor:name=”org.openoffice.myAddOn” oor:op=”replace”>
<prop oor:name=”Protocols” oor:type=”oor:string-list”>

The Java code skeleton looks more complicated than it really is. Most of the methods are necessary only for internal implementation reasons and don’t need to be changed at all. calls the dispatch() method each time the protocol handler routes commands. The fully implemented dispatch() method, which adds the “Hello World” message to the current document is shown in Listing 2. Note that only the lines in bold are new; the rest were part of the skeleton. The code basically determines the current document and then adds text to it. Notice also that the aURL parameter uses the specific class instead of the class.

Listing 2. Dispatch() method example.

public void dispatch( URL aURL, PropertyValue[] aArguments )
if ( aURL.Protocol.compareTo(“org.openoffice.myaddon:”) == 0 ) {
if ( aURL.Path.compareTo(“myAddOn”) == 0 ) {
XTextDocument xDoc = (XTextDocument) UnoRuntime.queryInterface(
XTextDocument.class, m_xFrame.getController().getModel());
xDoc.getText().setString(“Hello World”);

Since all commands fired by the user interface are passed through the dispatch() method, it’s necessary to filter explicitly for the namespace org.openoffice.myaddon, which represents the commands of our add-on. Finally, myAddOn is the command that’s fired when the user calls the add-on via the toolbar or menu.

Our add-on is now ready to deploy. Right click the project name and choose Deploy Office Extension from the context menu. NetBeans compiles all necessary files, creates an extension package file, and deploys it. Depending on the setup of the add-on, a new top-level menu and/or a toolbar are displayed in For our example both should show up (see the new menu in Figure 3).

Figure 3. The new add-on menu.


Developing more complex add-ons will probably require an extensive debugging session. However, as the add-ons run in’s JVM, NetBeans’ built-in debugger won’t work. We need remote debugging.

The OOo plugin module adds a command to the project’s context menu for starting a remote debugging session, which means that a manual setup of the client JVM or the remote debugger is not required. To use this feature, set a breakpoint within the dispatch() method, then call Debug Extension in Target Office as displayed in Figure 4. An instance will start automatically. Choose My Command from the add-on’s menu and the debugger will stop at the breakpoint.


Figure 4. Remote debugging context menu item.


Calc Add-Ins

Let’s now see how to create a Calc Add-In extension, which implements Calc functions. These functions are tightly integrated with the Calc application, so users will not recognize the differences between a standard function and one provided by an add-in; there are no new menus, toolbars or other evidences of an extension.

The Calc Add-In wizard is also located in the StarOffice/ category of the File>New Project dialog. Start the wizard and enter a name and location for the NetBeans project. We’ll use “myAddIn” for both names and “org.openoffice” again as the package name; also make sure Create backward compatible Calc Add-In is unchecked. Click Next to enter the name and parameters of the Calc functions.

The definition of a Calc Add-In function requires specifying the following parameters:

§ The name of the Java method which implements the Calc function.

§ The data type of the result of the new function.

§ The exception the Java implementation throws in case of errors. An additional dialog provides access to all available exceptions. (This property is optional.)

§ The Category where the function is listed within Calc's Function Wizard.

§ The function’s display name. This can be different from the name of the corresponding Java method.


Figure 5 shows how the wizard presents these parameters.

There are some additional parameters, which are all localizable. Calc functions are usually localized, having different names for each language; for example, the function Sum() in the English-language Calc is named Summe() in German Calc releases.

Figure 5. Deployment context menu

The Description parameter indicates the purpose of the function, and is displayed in Calc’s Function Wizard. Compatibility Name is necessary to deal with Microsoft Excel integration; it’s optional and usually not necessary. Finally we have the optional parameters of the Calc function. They require a specification of the data type, the implementation name, and the displayed name and description.

To create our simple Calc Add-In, set Name to “doubleValueImpl” and Type to double; leave the Exceptions section empty; set Category to “Add-In” and Displayed Name to “doubleValue”. Change Displayed Description to “Simple Calc Add-In: Doubles the given value”, and set Compatibility Name to “doubleValue”. Then provide the following values for the first parameter:

§ Name – “doubleValue”

§ Type – double

§ Displayed Name – “Value”

§ Displayed Description – “Value to be doubled”


Click Finish and several add-in-related files will be created. The most important is the Java class for the add-in implementation. There’s also the configuration file CalcAddin.xcu, which holds the add-in’s parameters. Functions exported by the add-in need to be defined in a new interface. The function names in this interface, together with the add-in’s service name, are used internally to identify an add-in function. The myAdd-In.idl and XmyAddIn.idl files define this service and the interface. They are used by tools and compilers available in the SDK, which build Java source and header files; but this process is hidden by the OOo plugin module.

Most of the initial skeleton code need not be changed. Our doubleValueImpl() method is called by the add-in and provides the implementation of its functionality. The implementation is really simple; it just doubles all values given by the user:


public double doubleValueImpl(double doubleValue)  {

   return doubleValue * 2;



NetBeans will complain that the XmyAddIn interface is missing, which is true so far. The reason is that the interface is defined in a UNO IDL (Interface Definition Language) file and not as a Java class. The plugin will create Java code based on this IDL file as well as other add-in related services and interfaces automatically when the project is compiled.

UNO (Universal Network Objects) is’s component technology.

That’s all. The Calc Add-In is fully implemented and ready to deploy. This can be done easily through the project’s context menu: choose Deploy Office Extension (see Figure 6) and NetBeans compiles all project-related files, builds an OXT extension package and installs it in

Figure 6. Defining a function and its parameters in the Calc Add-In wizard.

You can test the new add-in by starting a Calc instance and creating a new spreadsheet document. Then call the Calc’s Function wizard, where you’ll see the new function listed under the Add-In category. To verify that our new function works, enter in any cell the formula “=doublevalue(3)”. As expected, Calc will produce 6 as the result.

Client Applications

A client application is an external solution that makes use of the functionality instead of extending it. It can use OOo to convert or process any document supported by the office suite.

The Client Application wizard is also available in a New Project category. You just need to start the wizard and enter the name and location of the NetBeans project; no further settings are required. Click Finish, and the wizard creates the Java skeleton.

As a client application is not an integrated part of, most of the configuration and IDL files are not necessary. The NetBeans project consists of just a Java class and classpath settings for Java libraries.

You’ll notice that the code skeleton for a client application is quite small in comparison to the add-in and add-on skeletons. It is basically not much different from the Java class code generated by the general Java Class wizard. The implementation of the main() method contains a single line of code (besides exception handling):

XComponentContext xContext = Bootstrap.bootstrap();

The generated class works as a client of an process, with acting as a server with its own component context. The client program initializes the Universal Network Objects technology (UNO) and gets the component context from the OOo process. This initialization process establishes a pipe connection to a running process (starting a new process if necessary) and returns the remote component context.

The getServiceManager() method from the component context obtains the remote service manager from the process, which allows access to the complete office functionality available through the API:


XMultiComponentFactory xMCF =



Having the service manager, we can obtain the Desktop, which handles application windows and lets you load and create documents. The service represents this Desktop:


XDesktop xDesktop = (XDesktop) UnoRuntime.queryInterface(

XDesktop.class, xMCF.createInstanceWithContext(“”,xContext));

Now we have an instance of the Desktop without a document; but a text document is necessary to display our greeting. The XComponentLoader interface exports the loadComponentFromURL() method to load and create a document. See it in use in Listing 3. The private:factory/swriter URL creates a new text document.

Listing 3. Creating a text document.

XComponentLoader xComponentLoader =
(XComponentLoader) UnoRuntime.queryInterface(
XComponentLoader.class, xDesktop);

PropertyValue xEmptyArgs[] = new PropertyValue[0];

XComponent xComponent =
“_blank”, 0, xEmptyArgs);

XTextDocument xTextDocument =
(XTextDocument) UnoRuntime.queryInterface(
XTextDocument.class, xComponent);

The new document will show a cursor waiting for input. This input has to come from the client application. The OOo API uses a text cursor abstraction to add text to the document, represented by the XTextCursor interface:


XText xText = xTextDocument.getText();
XTextCursor xTextCursor = (XTextCursor) xText.createTextCursor();


The blinking cursor in the document and xTextCursor are independent of each other. Open- Writer uses MVC to separate the content/model from the view. The text cursor is the view in this context, and the cursors created by createTextCursor() are the model. You can create several models for text cursors.


Finally, the method insertString() adds the message to the document:

xText.insertString( xTextCursor, “Hello World”, false );

Components can be extended by Components. These are shared libraries or JAR files with the ability to instantiate objects that can integrate themselves into the UNO environment. A Component can access existing features of, and be used from within the office suite through the object communication mechanisms provided by UNO. In fact, the add-ons and add-ins described before are nothing more than specialized UNO components.

Components created by the Component wizard do not require access to a menu or to toolbars, nor do they extend the Calc function repository. They can be used to implement new interfaces and services. This flexibility and power makes it impossible to create a simple “Hello” component, and creating a fully working Component would go beyond the scope of this article. There are many excellent articles and documents available which describe the creation of new interfaces and services. Specifically, we refer you to Chapter 4 of the Developer Guide, which is a good source of examples.


In the past, writing components to integrate with required an extensive setup of the NetBeans infrastructure, with steep learning curves. Everything was documented somewhere but putting this information together took far too much effort. This has changed with the new plugin module we’ve covered in this article. The module takes care of integration chores and lets developers concentrate on the implementation of their extensions. Also, the module’s remote debugging capabilities make it much easier and faster to debug applications based on If you need to integrate with or StarOffice, give it a try!

The next releases of the plugin will integrate Java more closely into the scripting framework, and will let you use Java for typical scripting related tasks, combining the advantages of an integrated scripting language with the power of NetBeans and Java technology.


  The project’s homepage on the Wiki Developers Guide
  Download page of the latest release of the SDK


Kay Koll
( is responsible for the technical marketing of StarOfficae/ He has been working in various positions for StarOffice since 1995. Kay lives in Hamburg, Germany.


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