Jave Server Faces (JSF) Interview Questions And Answers - DoAnswers.com

JavaServer Faces technology includes:

1. A set of APIs for representing UI components and managing their state, handling events and input validation, defining page navigation, and supporting internationalization and accessibility.

2. A JavaServer Pages (JSP) custom tag library for expressing a JavaServer Faces interface within a JSP page.

Designed to be flexible, JavaServer Faces technology leverages existing, standard UI and web-tier concepts without limiting developers to a particular mark-up language, protocol, or client device. The UI component classes included with JavaServer Faces technology encapsulate the component functionality, not the client-specific presentation, thus enabling JavaServer Faces UI components to be rendered to various client devices. By combining the UI component functionality with custom renderers, which define rendering attributes for a specific UI component, developers can construct custom tags to a particular client device. As a convenience, JavaServer Faces technology provides a custom renderer and a JSP custom tag library for rendering to an HTML client, allowing developers of Java Platform, Enterprise Edition (Java EE) applications to use JavaServer Faces technology in their applications.

Ease-of-use being the primary goal, the JavaServer Faces architecture clearly defines a separation between application logic and presentation while making it easy to connect the presentation layer to the application code. This design enables each member of a web application development team to focus on his or her piece of the development process, and it also provides a simple programming model to link the pieces together. For example, web page developers with no programming expertise can use JavaServer Faces UI component tags to link to application code from within a web page without writing any scripts.

Developed through the Java Community Process under JSR-127, JavaServer Faces technology establishes the standard for building server-side user interfaces. With the contributions of the expert group, the JavaServer Faces APIs are being designed so that they can be leveraged by tools that will make web application development even easier. Several respected tools vendors were members of the JSR-127 expert group, which developed the JavaServer Faces 1.0 specification. These vendors are committed to supporting the JavaServer Faces technology in their tools, thus promoting the adoption of the JavaServer Faces technology standard.

The expert group is actively developing the specification for JavaServer Faces version 1.2. To check its current status, please see JSR-252.

In a nutshell, Faces has the following advantages over Struts:

Eliminated the need for a Form Bean

Eliminated the need for a DTO Class

Allows the use of the same POJO on all Tiers because of the Backing Bean

The primary advantages of Struts as compared to JavaServer Faces technology are as follows:
Because Struts is a web application framework, it has a more sophisticated controller architecture than does JavaServer Faces technology. It is more sophisticated partly because the application developer can access the controller by creating an Action object that can integrate with the controller, whereas JavaServer Faces technology does not allow access to the controller. In addition, the Struts controller can do things like access control on each Action based on user roles. This functionality is not provided by JavaServer Faces technology.

Struts includes a powerful layout management framework, called Tiles, which allows you to create templates that you can reuse across multiple pages, thus enabling you to establish an overall look-and-feel for an application.

The Struts validation framework includes a larger set of standard validators, which automatically generate both server-side and client-side validation code based on a set of rules in a configuration file. You can also create custom validators and easily include them in your application by adding definitions of them in your configuration file.

The greatest advantage that JavaServer Faces technology has over Struts is its flexible, extensible UI component model, which includes:
A standard component API for specifying the state and behavior of a wide range of components, including simple components, such as input fields, and more complex components, such as scrollable data tables. Developers can also create their own components based on these APIs, and many third parties have already done so and have made their component libraries publicly available.

A separate rendering model that defines how to render the components in various ways. For example, a component used for selecting an item from a list can be rendered as a menu or a set of radio buttons.

An event and listener model that defines how to handle events generated by activating a component, such as what to do when a user clicks a button.

Conversion and validation models for converting and validating component data.

A render kit defines how component classes map to component tags that are appropriate for a particular client. The JavaServer Faces implementation includes a standard HTML render kit for rendering to an HTML client.