What is EJB 3.0?

EJB 3.0 (Enterprise JavaBeans 3.0) is a component architecture for building distributed, transactional, secure and portable Java applications. It simplifies the development of enterprise applications by providing a managed environment for server-side components (EJBs). Key improvements in EJB 3.0 over previous versions include the use of annotations for configuration (reducing XML configuration), the introduction of POJO (Plain Old Java Object) based EJBs, and a more simplified programming model. EJBs are commonly used to implement business logic, manage data persistence (often via JPA), and handle transactions in enterprise Java applications. They come in several flavors: Session Beans (for business logic), Message-Driven Beans (for asynchronous messaging), and Singleton Beans (for shared state).