Apache Tomcat 6.x.

Apache Tomcat 6.x is the current focus of development. It builds upon the improvements made in Tomcat 5.5.x and implements the Servlet 2.5 and JSP 2.1 specifications. In addition to that, it includes the following improvements:

• Memory usage optimizations
• Advanced IO capabilities
• Refactored clustering

Within my work v 6.x is the de-facto standard for all new Apache Tomcat applications