Passivation

Activation is a process of transferring an enterprise bean from memory to secondary storage.

Passivation is the act of disassociating a stateful bean instance from its EJB object and saving its state. Passivation requires that the bean instance’s state be held relative to its EJB object. After the bean has been passivated, it is safe to remove the bean instance from the EJB object and evict it from memory. Clients are completely unaware of the deactivation process. Calling of ejbPassivate () for passivation is a warning to the bean that its held conversational state is about to be swapped out. It is important that the container inform the bean using ejbPassivate () so that the bean can relinquish held resources. The EJB container calls the ejbPassivate () method to give the bean a chance to release the resources or deal with the resources as the bean see fit.

The activation process is supported by the state management call methods ejbActivate () and ejbPassivate () methods which notify the stateful session bean that it is about to be activated or passivated respectively. The ejbPassivate () method is called immediately prior to the passivation of the bean instance.

Entity beans do not have conversational state that needs to be serialized like stateful beans; instead the state of entity bean instance is persisted directly to the data base. Entity beans do, however, leverage the activation callback methods ejbActivate () and ejbPassivate () to notify the instance when it is about to be swapped in or out of the instance pool. The ejbActivate () method is invoked immediately after the bean instance is swapped into the EJB object and the ejbPassivate () method is invoked just before the instance is swapped out of the instance pool.