Practical RichFaces, Second Edition

CHAPTER 2 GETTING STARTED
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Ajax in JSF 2
JSF 2 comes with basic Ajax functionality built in. If you have used RichFaces 3, then you will see that JSF
2 Ajax was greatly inspired by the popular RichFaces tag. You will see that the concepts
are the same, with a few things changed, such as attribute names. If you are new to RichFaces, don’t
worry, in this chapter we will cover everything from the beginning.
Ajax in JSF 2 comes in a form behavior. Notice that we call it a behavior instead of a
component. A behavior is a new concept in JSF 2. A behavior in JSF 2 is a client-side behavior
(functionality) that is added to a component. Let’s see how to use the standard Ajax functionality in JSF 2
before we get to RichFaces.
When working with Ajax in the context of JSF, you need to keep three things in mind: First, how to
send an Ajax request; second, what to process on the server (partial view processing); and third, what to
render (partial view rendering).
Sending an Ajax Request
Sending an Ajax request is pretty straight forward: you really just have one option and that’s using
behavior. This behavior is always attached to another UI component on a page; it’s never used
by itself. Listing 2-9 shows an example.
Listing 2-9. Sending an Ajax Request
That’s pretty simple, right? We just added the ability to fire an Ajax request when the value inside the
input field changes. The Ajax request is fired from the client (browser) and always on some browser
event, such as click, change, and so forth. To be more precise, it can be any event supported by the
parent UI component. Components represent HTML elements in the browser, so it’s all the events that
are supported by that particular HTML element.
The managed bean is shown in Listing 2-10.
Listing 2-10. Managed bean
@ManagedBean
@RequestScoped
public class Bean {
}
private String text;
// getter and setter
You probably noticed that we didn’t actually specify the event, but said that the Ajax request would
be fired when the value in the input field changes. The reason the Ajax request would fire on value
change is because the default valuechange event is used. Every UI component in JSF 2 has a standard