Quick start

Main classes

The minimum requirement is to implement two classes, one for the service declaration and one for the implementation itself.

Hello world

The sample is a dataset user service that simply displays a "hello" message, it can be launched from the action menu of a dataset:

The service implementation class must implement the interface UserService<DatasetEntitySelection>:

/**
 * This service displays hello world!
 */
public class HelloWordService implements UserService<DatasetEntitySelection>
{
	public HelloWordService()
	{
	}

	@Override
	public void setupDisplay(
		UserServiceSetupDisplayContext<DatasetEntitySelection> aContext,
		UserServiceDisplayConfigurator aConfigurator)
	{
		// Set bottom bar
		UIButtonSpecNavigation closeButton = aConfigurator.newCloseButton();
		closeButton.setDefaultButton(true);
		aConfigurator.setLeftButtons(closeButton);

		// Set content callback
		aConfigurator.setContent(this::writeHelloWorld);
	}

	private void writeHelloWorld(
		UserServicePaneContext aPaneContext, 
		UserServicePaneWriter aWriter)
	{
		// Display Hello World!

		aWriter.add("<div ");
		aWriter.addSafeAttribute("class", UICSSClasses.CONTAINER_WITH_TEXT_PADDING);
		aWriter.add(">");
		aWriter.add("Hello World!");
		aWriter.add("</div>");	
	}

	@Override
	public void setupObjectContext(
		UserServiceSetupObjectContext<DatasetEntitySelection> aContext,
		UserServiceObjectContextBuilder aBuilder)
	{
		// No context yet.
	}

	@Override
	public void validate(UserServiceValidateContext<DatasetEntitySelection> aContext)
	{
		// No custom validation is necessary.
	}

	@Override
	public UserServiceEventOutcome processEventOutcome(
		UserServiceProcessEventOutcomeContext<DatasetEntitySelection> aContext,
		UserServiceEventOutcome anEventOutcome)
	{
		// By default do not modify the outcome.
		return anEventOutcome;
	}
}

The declaration class must implement the interface UserServiceDeclaration.OnDataset:

/**
 * Declaration for service hello world!
 */
public class HelloWorldServiceDeclaration implements UserServiceDeclaration.OnDataset
{
	// The service key identifies the user service. 
	private static final ServiceKey serviceKey = ServiceKey.forName("HelloWorld");
	
	public HelloWorldServiceDeclaration()
	{
	}
	
	@Override
	public ServiceKey getServiceKey()
	{
		return serviceKey;
	}

	@Override
	public UserService<DatasetEntitySelection> createUserService()
	{
		// Creates an instance of the user service.
		return new HelloWordService();
	}

	@Override
	public void defineActivation(ActivationContextOnDataset aContext)
	{
		// The service is activated for all datasets instanciated with
		// the associated data model (see next example).
	}

	@Override
	public void defineProperties(UserServicePropertiesDefinitionContext aContext)
	{
		// This label is displayed in menus that can execute the user service.
		aContext.setLabel("Hello World Service");
	}

	@Override
	public void declareWebComponent(WebComponentDeclarationContext aContext)
	{
	}
}

In this sample, the user service is registered by a data model. The data model needs to define a schema extension that implements the following code:

public class CustomSchemaExtensions implements SchemaExtensions
{
	@Override
	public void defineExtensions(SchemaExtensionsContext aContext)
	{
		// Register the service.
		aContext.registerUserService(new HelloWorldServiceDeclaration());
	}
}

For details on the declaration of schema extensions, see SchemaExtensions.