Describe the life cycle of an entity bean.

Describe the life cycle of an entity bean.

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The life cycle of an entity bean is as shown in the following image:



An entity bean can have three states during its life as follows:

• Does not exist


• Pooled
• Method ready

In the does not exist state, the bean instance has not yet been created. To start an entity bean's life cycle, the container makes a new EntityContext. It then creates a new instance of the bean class by invoking the newInstance() method, and passes an EntityContext to the bean using the setEntityContext() method. At this point, the bean instance is moved into a bean pool. While in the pool, an instance may be used to execute ejbFind<method>, ejbSelect<method>, or ejbHome<method>.

An entity instance moves to the method ready state when the container calls the ejbCreate<method>() and ejbPostCreate<method>() methods, or the ejbActivate() method. In the method ready state, a bean instance represents a specific entity.

The container can invoke the ejbLoad() and ejbStore() methods whenever required. An ejbStore() method can be invoked from a business method, the ejbLoad() method, or the ejbStore() method.

The container may also call ejbPassivate() at any time to move the instance back into the pool. During passivation, resources should be released and reacquired upon activation.

An instance will be moved back to the pool if a transaction rollback occurs during the ejbCreate<method>() or ejbPostCreate<method>() operations. It can also move to the pool when the container calls the ejbRemove() method.

An instance is removed from the pool and goes to the does not exist state immediately after the container calls the unsetEntityContext() method.

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