C04.EJB(Enterprise JavaBean)


Enterprise Java Bean 3.1+(EJB 3)

EJB specification details how an application server provides:


EJB初學者常見的12個困惑問與答

http://developer.51cto.com/art/200802/66059.htm

http://www.infoq.com/cn/news/2010/02/jee6_ejb_31
http://www.mastertheboss.com/en/jboss-server/219-ejb-31-tutorial.html



EJB 3.1 帶來的改變


2009, EJB 進展至 3.1 的版本, 在這個版本我們看到了幾個明顯的特色,
  1. 更多來自開放社群修正參考, 提高更一致性的服務模式
  2. POJO 大量的使用, 引入 Java Annotation 減少開發者的工作量
  3. EJB 不再包含 Entity Beans, 由 JPA 2.0 取代
  4. 默認的“約定優於配置”獲得廣泛的應用 
  5. Singleton
  6. EJB Timer
  7. 無介面的 View
  8. @Asynchronous, 非同步服務
  9. 簡化的部署


Java EE 6新特性嘗鮮:EJB 3.1重要變化總覽, http://developer.51cto.com/art/200907/138734.htm

Different EJB types

You can also try using the @Stateful annotation. Alternatively, you could try the new @Singleton annotation for singleton instances. If you do, you may notice that there is are two annotations: javax.ejb.Singleton and javax.inject.Singleton. Why two singletons? The CDI singleton (javax.inject.Singleton) lets you define a singleton instance outside of EJB in case you are using CDI in a non-EJB environment. The EJB singleton (javax.ejb.Singleton) provides all the features of an EJB such as transaction management. Therefore, you have the choice depending on your needs and whether you are working in an EJB environment.



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JBoss 4 + EJB 3 在 Netbeans 6.5 中環境的設定Enterprise JavaBean 3 / 3.1

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