Recently I watched this webinar about Tomcat 7 presented by Mark Thomas and would like to share my thoughts on the subject and what I’ve learned. Servlet 3.0 The most prominent change is the support of Servlet 3.0 specification which supports such great features as asynchronous servlets – not used by default web-fragment.xml – you can specify parts of the configuration in your libraries which you plan to reuse The effective deployment descriptor (web.