This paper describes various web application frameworks and related emerging technologies pertinent to the Java EE model from a technical perspective. A definition of "web application framework" is specified, as this terminology has been widely used and implies drastically different meanings in different contexts. The value proposition of a web application framework is presented to illustrate how a framework can improve the application development productivity and quality. The design philosophy of web application frameworks is articulated. A comprehensive taxonomic scheme is defined to classify various software frameworks and web application frameworks into appropriate categories. Among dozens of web application frameworks available as commercial and open source solutions, the predominant products are investigated, followed by the selection guidelines and recommendations. A reference card is constructed to summarize the key aspects of web application frameworks. Relevant technologies and future trends are also discussed.