samples/mobilewebapp/src/main/webapp/WEB-INF/web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
              http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         version="2.5"
         xmlns="http://java.sun.com/xml/ns/javaee">

  <!--
    Require login. We only require login for the MobileWebApp.html page (instead of *.html) because
    we do not want to require login for the compiled GWT javascript files, which also end in .html.
  -->
  <security-constraint>
    <display-name>
      Redirect to the login page if needed before showing
      the host html page.
    </display-name>
    <web-resource-collection>
      <web-resource-name>Login required</web-resource-name>
      <url-pattern>/MobileWebApp.html</url-pattern>
    </web-resource-collection>
    <auth-constraint>
      <role-name>*</role-name>
    </auth-constraint>
  </security-constraint>

  <!-- RequestFactory -->
  <servlet>
    <servlet-name>requestFactoryServlet</servlet-name>
    <servlet-class>com.google.web.bindery.requestfactory.server.RequestFactoryServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>requestFactoryServlet</servlet-name>
    <url-pattern>/gwtRequest</url-pattern>
  </servlet-mapping>

  <filter>
    <filter-name>GaeAuthFilter</filter-name>
    <!--
      This filter demonstrates making GAE authentication
      services visible to a RequestFactory client.
    -->
    <filter-class>com.google.gwt.sample.gaerequest.server.GaeAuthFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>GaeAuthFilter</filter-name>
    <url-pattern>/gwtRequest/*</url-pattern>
  </filter-mapping>

  <!-- Default page to serve -->
  <welcome-file-list>
    <welcome-file>MobileWebApp.html</welcome-file>
  </welcome-file-list>

  <!-- Set the correct mime-type of media files. -->
  <mime-mapping>
    <extension>ogg</extension>
    <mime-type>audio/ogg</mime-type>
  </mime-mapping>
  <mime-mapping>
    <extension>mp3</extension>
    <mime-type>audio/mp3</mime-type>
  </mime-mapping>
  <mime-mapping>
    <extension>wav</extension>
    <mime-type>audio/wav</mime-type>
  </mime-mapping>
  <mime-mapping>
    <extension>ogv</extension>
    <mime-type>video/ogg</mime-type>
  </mime-mapping>
  <mime-mapping>
    <extension>mp4</extension>
    <mime-type>video/mp4</mime-type>
  </mime-mapping>

  <!-- Set the HTML5 appcache mime type -->
  <mime-mapping>
    <extension>manifest</extension>        
    <mime-type>text/cache-manifest</mime-type>        
  </mime-mapping>

</web-app>