Ajax has been in the limelight for over an year. While interest in the technology is high, there's still large scale ignorance as regards Ajax solutions that can be implemented in Java applications.

In this interview we speak to Jonas Jacobi, who is an expert in Ajax and JSF. Jonas has some great suggestions on Ajax adoption and also points out common pitfalls that we might ignore in our excitement to adopt Ajax asap.

IndicThreads >> Hi Jonas! Congratulations on the release of your book "Pro JSF and Ajax" and thanks for agreeing to this interview. Could you introduce yourself?

Jonas Jacobi >> Thank you! It's a pleasure to speak with you and to be able to reach out to your developer community.

Sure, for those of you who have not met me my name is Jonas Jacobi and I work as a J2EE Open Source Evangelist at Oracle. I recently published a book called "Pro JSF and Ajax: Building Rich Internet Component" which I co-authored with a very good friend, John Fallows (TXE Systems).

IndicThreads >> What do you think are the highlights of JSF and the reasons why you would recommend using JSF over competing frameworks / technologies?

Jonas Jacobi >> There are several reasons, of course, but there are two that sticks out as the main reasons why you would choose JSF over a competing frameworks. First reason is clearly the fact that JSF is an open standard and part of the newly released Java EE 5 specification. The second is related view technologies. As you are aware there is a tremendous buzz around Ajax and a lot of companies feel that they "just" have to have Ajax in their applications to be either competitive, or to provide adequate support for user interactivity.

"There is no migration path from a "pure" Ajax solution..."

What they don't think about is that there is no migration path from a "pure" Ajax solution. The JSF model brings a clearly defined split between the UI and the behavior. This model allows the application developer to code against the behavioral aspects of the application with out being impacted by the view technology rendered to the client.

"JSF model brings a clearly defined split between the UI and the behavior..."

IndicThreads >> Is JSF a "UI Only" thing or does it have implications for the business logic and data access part of the application?

Jonas Jacobi >> From a first glance it might seem like that, which may also be emphasized by the fact that the JSF specification states "JavaServer Faces (JSF) is a user interface (UI) framework". This statement has on occasion caused misunderstandings among developers believing that JSF is "UI Only". But JSF is a "(UI) framework", and as such it provides much more than just UI widgets.

"A key feature provided by JSF is the event model..."

We could probably spend an hour talking about the "extras" provided by JSF, but a key feature provided by JSF is the event model. This event model is borrowed from the JavaBeans spec and provides a strongly typed event model that allows the application to write server-side handlers (independent of HTTP) for client generated events. Very much like you do in Swing.

Another important feature is the Managed Bean facility. The Managed Beans facility offers a robust solution for creating and initializing managed beans e.g. a regular Java Class/POJO. When a Java Class/POJO has been registered in the JSF configuration file - faces-config.xml , it can be used in the JSF application. To access the managed bean developers will be using JSF's Expression Language. For example to bind a JSF component to one of the properties of a managed bean (Java Class/POJO), developers can use the expression #{thebean.name} as a value argument to a JSF component.