Java Platform, Enterprise Edition (Java EE) 8 The Java EE Tutorial

## What Is a JavaServer Faces Application?

The functionality provided by a JavaServer Faces application is similar to that of any other Java web application. A typical JavaServer Faces application includes the following parts.

- A set of web pages in which components are laid out.

- A set of tags to add components to the web page.

- A set of managed beans, which are lightweight, container-managed objects (POJOs). In a JavaServer Faces application, managed beans serve as backing beans, which define properties and functions for UI components on a page.

- A web deployment descriptor (`web.xml` file).

- Optionally, one or more application configuration resource files, such as a `faces-config.xml` file, which can be used to define page navigation rules and configure beans and other custom objects, such as custom components.

- Optionally, a set of custom objects, which can include custom components, validators, converters, or listeners, created by the application developer.

- Optionally, a set of custom tags for representing custom objects on the page.

Figure 7-1 shows the interaction between client and server in a typical JavaServer Faces application. In response to a client request, a web page is rendered by the web container that implements JavaServer Faces technology.

Figure 7-1 Responding to a Client Request for a JavaServer Faces Page

The web page, `myfacelet.xhtml`, is built using JavaServer Faces component tags. Component tags are used to add components to the `view` (represented by `myView` in the diagram), which is the server-side representation of the page. In addition to components, the web page can also reference objects, such as the following:

- Any event listeners, validators, and converters that are registered on the components

- The JavaBeans components that capture the data and process the application-specific functionality of the components

On request from the client, the view is rendered as a response. Rendering is the process whereby, based on the server-side view, the web container generates output, such as HTML or XHTML, that can be read by the client, such as a browser.

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