JSF Introduction

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All Rights Reserved.No material may be reproduced electronically or in print without written

permission from Liferay, Inc.

Objective

The goal of this tutorial is to create a Java Server Faces (JSF) Portlet within Liferay

1. What is JSF?

2. Why JSF vs. Struts?

Key Concepts

What are the main differences between a JSF Portlet and a JSP Portlet?– JSF follows the MVC pattern, and provides a

framework to develop robust web applications– JSP is a model 1 pattern; good for rapid

prototyping

What is JSF?

JavaServer Faces technology is a framework for building user interfaces for web applications. JavaServer Faces technology includes:

• 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.

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

Reference: Sun Developer Network. JavaServer Faces Technology FAQ. http://java.sun.com/javaee/javaserverfaces/reference/faqs/index.html

What are the benefits of JSF?

• Container AgnosticDevelopment is the same whether your application is servlet or portlet based

• Tree-based Component ModelAll components on the JSP page (JSF tags) are persisted in memory

This gives you the ability to insert a table or a button in the middle of a page at runtime rather than code it in your JSP. Elements on the page can be traversed in the POJO.

• Enforces Best PracticesEverything is encapsulated in a component. Consistent development means that the code is easier to maintain.

• Highly CustomizableEvery level of the JSF life cycle is customizable. For example, JSF is not tied to a presentation layer and does not have to use the HTTP protocol.

What are the key differences between JSF and Struts?

Struts is an open-source Java web application framework whose architecture is based on the Model-View-Controller design pattern in which requests are routed through a controller that provides overall application management and dispatches the requests to application components.

JavaServer Faces technology is a user-interface framework for Java web applications.  It is focused on the view tier of an MVC-based architecture.

The Struts and JavaServer Faces technology frameworks do have some overlapping functionality; however each framework has its advantages, and developers can use certain features of both frameworks in a single application.

Reference: Sun Developer Network. JavaServer Faces Technology FAQ. http://java.sun.com/javaee/javaserverfaces/reference/faqs/index.html

Advantages of JSF over Struts

The main advantage of JSF 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.

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.

Reference: Sun Developer Network. JavaServer Faces Technology FAQ. http://java.sun.com/javaee/javaserverfaces/reference/faqs/index.html

JavaServer Faces separates the definition of a component from its rendering, so you can render your components in different ways or even to different clients, such as a WML client.

JavaServer Faces technology allows you to extend the standard set of components and create entirely new components.

Struts has no notion of server-side components, which means that it has no event model for responding to component events and no facility for saving and restoring component state.  While Struts does have a useful tag library for rendering components on the page, these components have no object representation on the server and they can only be rendered to an HTML client.

The controller logic is implemented in POJOs so there is no need to implement Struts’ processAction or execute methods.

JSF provides tags that specify which method will be called, further simplifying the controller logic. <h:commandButton action="#{myBean.addBook}"> calls myBean.addBook()

Reference: Sun Developer Network. JavaServer Faces Technology FAQ. http://java.sun.com/javaee/javaserverfaces/reference/faqs/index.html

Revision HistoryEdward Shin 8/28/2006 Updated for Liferay 4.1.1

James Min 01/17/2007 4.2.1