Murthy,
Basically, TomEE is Tomcat with JavaEE libraries. Here is a quote from its website "Tomcat with added EE features - TomEE".
So, the configuration shouldn't differ too much from a "plain" Tomcat.
Concerning the exception that you provided. You can try to remove the following lines from the webapps\ajaxswing\WEB-INF\web.xml (or directly in the ajaxswing.war so that future deploys will have the same changes):
<servlet>
<servlet-name>snoop</servlet-name>
<servlet-class>SnoopServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>snoop</servlet-name>
<url-pattern>/snoop/*</url-pattern>
</servlet-mapping>
Let me know if it works for you
Best regards,
AjaxSwing team