JBoss - Seam

What is JBoss Seam

EJB 3.0 and JSF are perhaps the most exciting new developments in the Java EE 5 platform. Seam is an innovative new application framework that integrates the EJB 3.0 component model with JSF as a presentation tier. Seam builds upon the standard extension points provided by both specifications and provides a set of Java annotations that extends the standard annotations defined by the EJB specification. In addition, Seam introduces several innovative new ideas: managed conversations, declarative and contextual application state management, bijection and integrated business process management.

Traditional web applications are incredibly vulnerable to bugs and performance problems relating to state management. Developers are forced to handle issues like back button navigation, multi-window browsing, session size management in an utterly ad-hoc fashion. Access to transactional components from the web tier has also been problematic. J2EE provided no way to have simultaneous access to state held in contexts associated with the web request, and state held in transactional resources accessed via EJB. Finally, J2EE had no first-class construct for representing state associated with a long-running business process. Seam tackles all these problems, and provides a uniform model for stateful components in Java EE 5.
Like all JBoss software, this entire software stack is free. The full source code of this sample application is available in the examples/booking directory of the Seam distribution. There is even a 10-minute flash demo showing how to build a Seam web application from ground up.


The first application framework for EJB 3.0

EJB 3.0 has changed the notion of EJB components as coarse-grained, heavy-weight objects to EJBs as lightweight POJOs with fine-grained annotations. In Seam, any class may be an EJB - Seam eliminates the distinction between presentation tier components and business logic components and brings a uniform component model to the EE platform.

Backward compatible with J2EE

But Seam is not limited to environments that support EJB 3.0. Seam may be used in any J2EE environment, or even in plain Tomcat.

The easy way to do AJAX

Seam 1.1 integrates open source JSF-based AJAX solutions like ICEfaces and Ajax4JSF with Seam's unique state and concurrency management engine. You can add AJAX to your applications with ease, without the need to learn JavaScript, and you will be protected from potential bugs and performance problems associated with the switch to AJAX.

A revolutionary approach to state management

Before Seam, the HTTP session was the only way to manage Web application state. Seam provides multiple stateful contexts of different granularity from the conversation scope to the business process scope, liberating developers from the limitation of HTTP sessions. For example, developers can write Web applications with multiple workspaces that behave like a multi-window rich client.

Manage "flow"

Seam integrates transparent business process management via JBoss jBPM, making it easier than ever to model, implement and optimize complex collaborations (workflow) and complex user interactions (pageflow).

Easy integration testing

Seam components, being POJOs, are by nature unit testable. But for complex applications, unit testing alone is insufficient. Therefore, Seam provides for easy testability of Seam applications as a core feature of the framework. You can write JUnit or TestNG tests that reproduce a whole interaction with a user, exercising all components of the system, and run them inside your IDE.

References
http://www.jboss.com/products/seam

http://www.oreillynet.com/onjava/blog/2007/10/after_struts_what.html

http://labs.jboss.com/jbossseam/gettingstarted