EJB Life Cycle

EJB 3.0

Stateless 3

Stateful 3

Stateless

• Can be created and destroyed with each call - unlikely
• Only one client per running bean

Create

1. Must have no arg constructor (Class.newInstance() calls this)
2. Resources marked with annotations injected
3. Method called annotated with @javax.annotation.PostConstruct or specified in the deployment descriptor
   1. contract: void, no args, no checked exceptions

<post-construct>
  <lifecycle-callback-method>postCreate</lifecycle-callback-method>
</post-construct>
<pre-destroy>
  <lifecycle-callback-method>tidyUp</lifecycle-callback-method>
</pre-destroy>

Destroy

• methods marked with @PreDestroy
  • must be only one void, no args, no checked exceptions

Exceptions

• System exception => Bean is destroyed and @PreDestroy is not called
  • System exception is any unchecked exception (which isn't annotated with @ApplicationException)

MDB

Essentially the same as stateless

EJB 2.0

Stateful 2.0

Stateless

• same lifecycle as EJB 3

clients can call remove - this invalidates the bean for this client and returns it to the pool

Stateful

• same lifecycle as EJB 3 different interface

java serialisation equivalent technology used to passivate and store bean state.

• represents client state - cached but not (may be passivated - stored temporarily)
• passivate stores state to filesystem

Create EJB

1. newInstance()
2. setSessionContext(sc)
3. ejbCreate()

Start Transaction

1. afterBegin()

Commit Transaction

1. beforecompletion()
2. afterCompletion(true)

Rollback Transaction

1. afterCompletion(false)

Passivate

1. ejbPassivate()

• Transaction state, session context etc are maintained though passivation

Activate

1. ejbActivate()

• transients are undefined when reactivated - unlike serialisation

Client finished - calls remove()

1. ejbRemove()

Timeout

Container may call @PreDestroy but this isn't required by spec