What is passivation and activation?

Richard Monson-Haefel

Passivation and activation are two phases of a resource management technique that reduces the number of bean instances needed to service all clients. Passivation is the process of disassociating a bean instance from its EJB object so that the instance can be reused or evicted to conserve memory. Activation is the process of associating a bean instance with an EJB object so that it can service a request. Beans are passivated when there is a lull in their use and activated when the EJB object receives a client request.

The java.ejb.SessionBean and javax.ejb.EntityBean interface include two callback methods that notify a bean instance when it is about to passivated or activated. The ejbPassivate( ) method notifies a bean that it is about to passivated; the ejbActivate( ) method notifies a bean that it is about to activated.

The mechanisms employed in passivation and activation change depending on the bean type. Stateful beans are usually evicted, while entity beans and stateless beans are pooled. A more detailed account of how different bean types passivated and activated is found under the FAQs for that type.

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