Parleys.com is an e-learning platform that provide a unique experience of online and offline viewing presentations, with integrated movies and chaptering, from the top notch developer conferences and about 40 JUGs all around the world.
Stephan Janssen (the Devoxx man and Parleys webmaster) presented at the GlassFish Community Event at JavaOne 2012 and shared why they moved from Tomcat to GlassFish. The move paid off as GlassFish was able to handle 2000 concurrent users very easily. Now they are also running Devoxx CFP and registration on this updated infrastructure. The GlassFish clustering, the asadmin CLI, application versioning, and JMS implementation are some of the features that made them a happy user.
Recently they migrated their application from Spring to Java EE 6. This allows them to get locked into proprietary frameworks and also avoid 40MB WAR file deployments. Stateless application, JAX-RS, MongoDB, and Elastic Search is their magical forumla for success there. Watch the video below showing him in full action: More details about their infrastructure is available here.