But now Rich Internet Applications (RIA) place a lot back in the Web browser function, so the server-side technology alone is no longer enough. Developers who are doing the work server-side over the years have expanded their horizons to provide rich client side experience. Enter the Flex 4 development efforts by bestselling author Larry Ullman. Flash-Flex is a powerful duo to provide experience, rich client side. All server-side code in this book is PHP, and this view of data-centric and greater support for PHP is the main focus in Flex 4. Taking advantage of what Flex 4 that is offered, developers can quickly learn how to create RIA, some of whom interact with PHP scripts running on the server.