Alef Arendsen has been a Core Spring developer since mid-2003 and has worked on Spring MVC and other parts of the Spring Framework. He also wrote large parts of the initial Spring Framework reference documentation. Currently, Alef Arendsen is one of Interface21's most-wanted trainers and when he's not teaching developers in his unique inspiring way or providing consulting services, he works on providing the community with value-added services.

Before joining Interface21 as a founder, in 2002 Alef set up a software consulting company called JTeam, still operating solidly in the Dutch market. Here he designed worked on large-scale Java projects for financial organizations, online and offline media companies as well as healthcare institutions.

Oren Eini is a senior developer in We!, a consulting group based in Israel, focusing on architecture, data access and best practices.

Most often, he is working on building complex business systems using .Net, NHibernate and Castle's Frameworks. Oren is an active member in several Open Source projects, including (but not limited :-) ) NHibernate, Castle and Rhino Mocks.

He has a blog at http://www.ayende.com/Blog/ where he publish his thought every once in a while.

Erik Dörnenburg is an application architect and developer at ThoughtWorks Inc., where he is helping clients with the design and implementation of large-scale enterprise solutions. Building on his experience with J2EE, Microsoft .NET and other environments, Erik is continually exploring new patterns of enterprise software.

Before joining ThoughtWorks Erik was Technical Director at Pixelpark UK, a new media company, where he integrated enterprise systems with web-based solutions and a variety of digital delivery channels. His career in enterprise software began in the early nineties on the NeXTSTEP platform and Erik has been an advocate of agile, test-driven, object-oriented development and Open Source software for many years. He holds a degree in Informatics from the University of Dortmund and has studied Computer Science and Linguistics at the University College Dublin.

Justin Gehtland is President and co-founder of Relevance, Inc., a development, consulting and training organization based in Chapel Hill, North Carolina.

He has written commercial applications in Ruby, Java, C#, VB, Perl and other languages, and is the author or co-author of eight different technical books, including "Pragmatic Ajax", "Rails for Java Developers", and the Jolt(tm) award winning "Better, Faster, Lighter Java". He is a well-traveled speaker, appearing at RailsConf, RubyConf, RailsEdge, JAOO, and the No Fluff, Just Stuff tour.

He is particularly proud to be involved in the continuing development of the Streamlined open source framework (streamlinedframework.org).

He currently lives in Durham, NC, with his wife, 2 kids, 2 dogs and 2 cats.

Eberhard Wolff has several years of experience as a developer, consultant and trainer for enterprise solutions based on Java technologies.

He is authored three books including the first German book on Spring, which is also the first book to cover Spring 2.0. He regularly contributes to conferences and writes articles for several journals.

Eberhard is a founding member of the Java Champions and works as Managing Consultant for Interface21 in Germany.