David R. Heffelfinger is the Chief Technology Officer (CTO) at Ensode Technology, LLC, a software consulting firm based in the Greater Washington DC area. He has been architecting, designing, and developing software professionally since 1995. He has been using Java as his primary programming language since 1996. He has worked on many large-scale projects for several clients, including the U.S. Department of Homeland Security, Freddie Mac, Fannie Mae, and the U.S. Department of Defense. He has a master's degree in software engineering from Southern Methodist University, Dallas, Texas. David is the editor-in-chief of Ensode.net (http://www.ensode.net), a website on Java, Linux, and other technologies. David is a frequent speaker at Java conferences such as JavaOne. You can follow David on Twitter at @ensode.