vaadin-framework/documentation/advanced/advanced-osgi.asciidoc

---
title: Vaadin OSGi Support
order: 19
layout: page
---

[[advanced.osgi]]
= Vaadin OSGi Support

IMPORTANT: The OSGi support as described here is currently being developed and only available in the Framework 8.1 prerelease versions, starting from 8.1.0.beta1.

Vaadin applications can be deployed on an OSGi compatible servlet container, or on Liferay 7 as OSGi portlets.

An OSGi application typically consists of multiple bundles that can be deployed separately. Multiple versions of each bundle can be present, and the OSGi runtime resolves their dependencies at run-time based on bundle manifests.

To deploy Vaadin applications as OSGi bundles, static resources (including themes and widget sets) must be published using the appropriate APIs to enable using multiple Vaadin versions on the same server.

The application is typically packaged as a JAR file, and needs to have a valid OSGi bundle manifest which can be created e.g. by the `bnd-maven-plugin`. All the dependencies of the application should be available as OSGi bundles.

[[advanced.osgi.servlet]]
== Publishing a Servlet With OSGi

To deploy the app as a servlet all we need to do is annotate the [classname]#MyUIServlet# class with [literal]#@Component(service = VaadinServlet.class)#. The Vaadin integration will track this registration and use HttpWhiteboard specification to register a servlet with the location of the Vaadin resources properly configured. This means that the user can specify a set of HttpWhiteboard properties in the [interfacename]#@Component# declaration.

The [interfacename]#@WebServlet# annotation settings will be used to configure the urlPatterns and async parameters.

[source, java]
----
import org.osgi.service.component.annotations.Component;
...
@Component(service = VaadinServlet.class)
@WebServlet(urlPatterns = "/*", name = "MyUIServlet", asyncSupported = true)
@VaadinServletConfiguration(ui = MyUI.class, productionMode = false)
public static class MyUIServlet extends VaadinServlet {
}
----


[[advanced.osgi.resources]]
== Publishing Static Resources With OSGi

Vaadin Framework 8.1 and later versions provide two supported ways of publishing static resources for OSGi: by making OSGi services implementing an interface or by explicit calls to a service.

The easiest way to publish a theme or a widgetset is to create a class implementing the interface [interfacename]#OsgiVaadinTheme# or [interfacename]#OsgiVaadinWidgetset# and annotating it with [interfacename]#@Component# to make it an OSGi service. This automatically publishes the theme or the widget set from the bundle at a path that contains the Vaadin Framework version used by the application.

[source, java]
----
@Component
public class MyTheme extends ValoTheme implements OsgiVaadinTheme {
    public static final String THEME_NAME = "mytheme";

    @Override
    public String getName() {
        return THEME_NAME;
    }

}
----

Alternatively, an OSGi bundle activator or an SCR Component [interfacename]#@Activate# method can obtain an instance of [classname]#VaadinResourceService# from [classname]#OsgiVaadinResources# and explicitly call its methods to publish a theme, a widget set or an individual file in the bundle as a static resource at the correct path.

[source, java]
----
  VaadinResourceService service = OsgiVaadinResources.getService();
  service.publishTheme("mytheme", httpService);
----

In addition to these approaches, it is also possible to repackage all the static resources of an application to a single bundle and export the [filename]#/VAADIN# directory. This can be useful e.g. when migrating an old Vaadin OSGi application in an environment that does not support parallel deployments of multiple versions of the application.