org.apache.catalina.ServerFactory.getServer() equivalent in Tomcat 7

What is the equivalent of org.apache.catalina.ServerFactory.getServer() in Tomcat 7 or what would be the best way to retrieve org.apache.catalina.Session instances ?

Here is a sample code that used to work on Tomcat 6.0:

public List<org.apache.catalina.Session> findActiveSessions() throws ServiceException {
    StandardEngine engine = (StandardEngine) ServerFactory.getServer().findService("Catalina").getContainer();
    StandardContext  context = (StandardContext) engine.findChild(engine.getDefaultHost())
        .findChild(ServletActionContext.getServletContext().getContextPath()); 
    List<org.apache.catalina.Session> list = new ArrayList<org.apache.catalina.Session>();
    for (org.apache.catalina.Session session : context.getManager().findSessions()) {
        list.add(session);
    }
    return list;
}