The Web Tier (Your First Cup: An Introduction to the Java EE Platform)

Your First Cup: An Introduction to the Java EE Platform

The web tier consists of components that handle the interaction between clients and the business tier. Its primary tasks are the following:

Dynamically generate content in various formats for the client.
Collect input from users of the client interface and return appropriate results from the components in the business tier.
Control the flow of screens or pages on the client.
Maintain the state of data for a user's session.
Perform some basic logic and hold some data temporarily in JavaBeans^TM components.

The following Java EE technologies are used in the web tier in Java EE applications:

Table 2–1 Web-Tier Java EE Technologies


Technology	Purpose
Servlets	Java programming language classes that dynamically process requests and construct responses, usually for HTML pages
JavaServer^TM Faces technology	A user-interface component framework for web applications that allows you to include UI components (such as fields and buttons) on a page, convert and validate UI component data, save UI component data to server-side data stores, and maintain component state.
JavaServer Faces Facelets technology	Facelets applications are a type of JavaServer Faces applications that use XHTML pages rather than JSP^TM pages.
Expression Language	A set of standard tags used in JSP and Facelets pages to refer to Java EE components.
JavaServer Pages (JSP)	Text-based documents that are compiled into servlets and define how dynamic content can be added to static pages, such as HTML pages.
JavaServer Pages Standard Tag Library	A tag library that encapsulates core functionality common to JSP pages
JavaBeans Components	Objects that act as temporary data stores for the pages of an application