VaadinOSGiServlet.java

package com.vaadin.osgi;

import java.util.HashSet;
import java.util.Set;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

import org.osgi.service.component.ComponentFactory;
import org.osgi.service.component.ComponentInstance;

import com.vaadin.Application;
import com.vaadin.terminal.gwt.server.AbstractApplicationServlet;
import com.vaadin.terminal.gwt.server.WebApplicationContext;

/**
 * Used to create instances of applications that have been registered with the
 * container via a component factory.
 * 
 * @author brindy
 */
@SuppressWarnings("serial")
public class VaadinOSGiServlet extends AbstractApplicationServlet {

	private final ComponentFactory factory;

	private Set<VaadinSession> sessions = new HashSet<VaadinSession>();

	public VaadinOSGiServlet(ComponentFactory factory) {
		this.factory = factory;
	}

	@Override
	protected Class<? extends Application> getApplicationClass()
			throws ClassNotFoundException {
		// not used as the component factory creates instances for us
		// but has to return something or getSystemMessages causes a NPE
		return Application.class;
	}

	@Override
	protected Application getNewApplication(HttpServletRequest request)
			throws ServletException {
		final VaadinSession info = new VaadinSession(factory.newInstance(null),
				request.getSession());

		info.session.setAttribute(VaadinOSGiServlet.class.getName(),
				new HttpSessionListener() {

					@Override
					public void sessionDestroyed(HttpSessionEvent arg0) {
						info.dispose();
					}

					@Override
					public void sessionCreated(HttpSessionEvent arg0) {

					}

				});
		System.out.println("Ready: " + info);
		return (Application) info.instance.getInstance();
	}

	@Override
	public void destroy() {
		super.destroy();

		HashSet<VaadinSession> sessions = new HashSet<VaadinSession>();
		sessions.addAll(this.sessions);
		this.sessions.clear();
		for (VaadinSession info : sessions) {
			info.dispose();
		}
	}

	/**
	 * Track the component instance and session. If this is disposed the entire
	 * associated http session is also disposed.
	 */
	class VaadinSession {

		final ComponentInstance instance;

		final HttpSession session;

		public VaadinSession(ComponentInstance instance, HttpSession session) {
			this.instance = instance;
			this.session = session;
			sessions.add(this);
		}

		public void dispose() {
			System.out.println("Disposing: " + this);
			Application app = (Application) instance.getInstance();
			if (app != null) {
				app.close();
			}
			
			instance.dispose();

			session.removeAttribute(VaadinOSGiServlet.class.getName());
			session.removeAttribute(WebApplicationContext.class.getName());

			sessions.remove(this);
		}

	}

}