vaadin + Google Engine : set appengine-web.xml

<?xml version="1.0" encoding="utf-8"?>

<appengine-web-app xmlns="http://appengine.google.com/ns/1.0">

    <application>unistussystem</application>

    <version>2</version>

    <system-properties>

        <property name="java.util.logging.config.file" value="WEB-INF/logging.properties"/>

    </system-properties>

    

    <sessions-enabled>true</sessions-enabled>

</appengine-web-app>