In this article, Sergey Smirnov discusses, primarily through the use of a step-by-step example, G4jsf, a new integration library for facilitating the combination of Google Web Toolkit and JavaServer Faces as complimentary technologies.

The Google Web Toolkit (GWT) has attracted a lot of attention lately as a way to make it easier for developers to add AJAX Web 2.0 features to their applications. Like other approaches, the designers of GWT have tried to insulate developers from having to deal with the underlying JavaScript, which implements these features. GWT achieves this goal of simplifying the creation of advanced client-side JavaScript widgets by generating them from Java code. At the same time, JavaServer Faces (JSF) has gathered more and more momentum as a general server-side framework for Web applications. The key to its success has been its top-to-bottom component-based approach to Web development. Although JSF comes with its own standard out-of-the-box UI components, it is designed for the easy inclusion of other component libraries. While both of these technologies are incredibly beneficial on their own, they also both complement each other extremely well. GWT is server-side-agnostic, while JSF's component-based architecture can easily accommodate any approach for rendering components.

What do you think of G4jsf?

I think this is awesome. I was looking for a way to accomplish this type of integration. It is nice to see that somebody has already come up with one. This is something I can use straight away. I hope it works well.

Wouldn't using GWT's built-in RPC mechanism be a lot simpler?

For those of us with investments in JSF already, if I'm understanding this correctly, I think the advantage is that we can still have JSF paint most of the page and handle the stuff we have it doing already (layout, form validation, navigation, etc). But then we can add in gwt components to handle the dynamic ajax type interactions. I'm excited to try it out.

For those of us with investments in JSF already, if I'm understanding this correctly, I think the advantage is that we can still have JSF...

Yes, It is most common kind of use cases, we kept in mind. For example, you have a business and the web site, written with JSF that presents this business in Internet. If you want to show the office on the map that is nearest to a user's location, the functionality based of the Google Map GWT component is a simple and presentable way to accomplish this. a4j-gwtMap example referenced at the bottom of the G4jsf home page - https://ajax4jsf.dev.java.net/nonav/ajax/gwt/gwt-cdk.html - shows this component in use. Meanwhile, the strong server-side background provided by JSF might be a good accelerator for developing one-page application with rich user interface developed with GWT. What we were going to accomplish started this open source project was a multiplication of two technologies powers worked together.

Wouldn't using GWT's built-in RPC mechanism be a lot simpler?

Bob, G4jsf is not about replacement for RPC, but how the GWT's built-in RPC mechanism is integrated into JavaServer Faces environment. So, please, do not interpret it like an alternative. It is an extension from this point of view.

why we are so attached to jsf?

In short: because the enterprise level stateful application required on the market also. JavaServer Faces is a server technology just by definition. It has a rich server architecture. GWT is a rich UI (i.e., offers the rich client functionality). Server + Client : this is a motivation for our integration solution.