Editing EJB (section)

====EJB 3.0====
* 05/2006
* belongs to JEE 5
Version 3.0 vereinfacht die Implementierung. Getrieben wurde dies durch konkurrierende lightweight frameworks wie [[Spring]] oder [[Hibernate]], durch neue Java 5 Erweiterungen oder neue Design-Prinzipien wie Aspect Oriented Programming (AOP).
EJB 3.0 is based on:
*annotations, that means one source and compile time checking (eleminates the xml deployment descriptors in 80%, but it can still be there. Descriptor overwrites annotations)
*container managed POJOs (no framework specific implementations like interfaces (javax.ejb.SessionBean, javax.ejb.EntityBean, javax.ejb.MessageDrivenBean), throws ; no home interface) with arbitrary inheritance structures
*dependency injection (Holywood principle: don't call us, we call you; EJB isn't lookup up anymore, but specified by annotation and the container manages the rest, also cault inversion of control (IOC))
*business interface as POJI (no inheritance from javax.ejb.EJBObject or javax.ejb.EJBLocalObject, no technical exceptions)
*configuration by exceptions (only the special case has be described)
*improvement of testability (no container for test necessary)
*improvement of database queries (JPA instead of native SQL)
*cross-cutting concern (Auslagerung von zentralen Funktionalitäten in interceptors z.B. zum Logging oder zentraler fachlicher Funktionalitäten)
*shorter development cycles (because less errors, which are detected after build and deploy)
*internal: change from RMI/IIOP to RMI