ZK includes Ajax-based event-driven engine, rich sets of XML User Interface Language (XUL) and XHTML components, and markup languages. ZK rich client framework takes a server-centric approach is called: sync the contents of the components and the event pipelining between clients and servers are automatically done by the engine and pipe code Ajax completely transparent to web application developers. Therefore, end users get a rich user interface interactivity and responsiveness that moves together with desktop applications, while for programmers, the development is similar in simplicity with desktop applications. This book is a Developer's Guide that steps you through the ZK framework with examples.