Patterns: Implementing Self-Service in an SOA Environment

Chapter 6. Technology options 117

JSF manages designated model data objects by handling their initialization,

persistence over the request cycle, and cleanup.

򐂰 Validation and error feedback

JSF allows direct binding of reusable validators to UI components. The

framework also provides a queue mechanism to simplify error and message

feedback to the application user. These messages can be associated with

specific UI components.

򐂰 Internationalization

JSF provides tools for internationalizing Web applications, supporting

number, currency, time, and date formatting, and externalizing of UI strings.

JSF is particularly well-suited to implement the MVC architectural pattern.

Specifically, the JSF framework maps to the pattern as follows:

򐂰 Model

Managed beans make up the model of a JSF application. These Java beans

typically interface with reusable business logic components or external

systems, such as a mainframe or database.

򐂰 View

JSPs make up the view of a JSF Web application. These JSPs are created by

combining model data with predefined and custom-made UI components.

򐂰 Controller

The FacesServlet, which drives navigation and object management, makes

up most of a JSF application’s controller. Event listeners also contribute to the

controller logic.

Note that unlike other frameworks supporting the MVC pattern, JavaServer

Faces are a standard component of the J2EE 1.4 specification. Therefore, it has

received wide support from IBM and other leading vendors.

6.3.4 Struts

Struts is a Servlet-JSP framework offered by the Apache Software Foundation.

Struts supports application architectures based on the Model II approach, which

is an implementation of the traditional MVC paradigm discussed earlier.

Struts addresses a number of common design and implementation issues

associated with most servlet projects:

򐂰 Mapping HTTP parameters to JavaBeans

򐂰 Standard input validation

򐂰 Standard error display