Menu
▾
▴
[Andromdaplugins-cvs] CVS update: cartridges/andromda-ejb3/src/site/xdoc howto14.xml
|
From: Vance K. <va...@us...> - 2006-03-03 04:07:17
|
User: vancek
Date: 06/03/02 20:07:10
Added: andromda-ejb3/src/site/xdoc howto14.xml
Log:
initial revision
Revision Changes Path
1.1 cartridges/andromda-ejb3/src/site/xdoc/howto14.xml
Index: howto14.xml
===================================================================
<?xml version="1.0" encoding="iso-8859-1"?>
<document>
<properties>
<author email="va...@us...">Vance Karimi</author>
<title>AndroMDA - EJB3 - Lifecycle Callbacks</title>
</properties>
<body>
<section name="Lifecycle Callbacks">
<p>
There are a couple of different ways to define the lifecycle callbacks using the
EJB3 cartridge. This howto will provide the necessary details on how you can implement
the callback handlers for entity, session and message-driven beans.
</p>
<p>
You have two basic choices on how you want to implement the lifecycle callbacks. You can
annotate methods in the bean class to indicate the individual callback or you can separate
out the callback implemention to a listener class for entity beans or interceptor for
session and message-driven beans. These options are discussed below.
</p>
<a name="Entity_Bean_Callbacks"/>
<subsection name="Entity Bean Callbacks">
<p>
You can define any number of the following callbacks in an entity bean by modelling the appropriate
stereotype on an entity operation. You can only define 1 lifecycle callback stereotype
per entity operation.
<ul>
<li>
PrePersist - <![CDATA[<<PrePersist>>]]> - Invoked before the entity is created in
the database and will cascade to all entities by way of the cascaded operation.
</li>
<li>
PostPersist - <![CDATA[<<PostPersist>>]]> - Invoked after the entity is created in
the database and will cascade to all entities by way of the cascaded operation.
</li>
<li>
PreRemove - <![CDATA[[<<PreRemove>>]]> - Invoked before the entity is deleted in
the database and will cascade to all entities by way of the cascaded operation.
</li>
<li>
PostRemove - <![CDATA[<<PostRemove>>]]> - Invoked after the entity is deleted in
the database and will cascade to all entities by way of the cascaded operation.
</li>
<li>
PreUpdate - <![CDATA[<<PreUpdate>>]]> - Occurs right before the database is updated.
</li>
<li>
PostUpdate - <![CDATA[<<PostUpdate>>]]> - Occurs immediately after the database
has been updated.
</li>
<li>
PostLoad - <![CDATA[<<PostLoad>>]]> - Occurs right after the data has been loaded
from the database and associated with the entity.
</li>
</ul>
</p>
<p>
Due to the limitations of the EJB3 cartridge when it comes to
<a href="howto9.html">inheritance</a>, you may need to assign a callback listener class to
the entity. In an entity inheritance hierarchy, there are times where you do not have an
implementation class for the entity and therefore do not have the ability to implement the
lifecycle callback if you model the callback stereotype on the entity operation.
</p>
<p>
To seperate out the callback for the entity into an entity listener class, simply model the
<![CDATA[<<Listener>>]]> stereotype on the entity class. This will add the
<code>@EntityListener</code> annotation to the class. The associated listener class includes
all the lifecycle callbacks for the entity. The listener is generated on the first
run and will never be overwritten, so you are free to add your implementation to the lifecycle
callback operations.
</p>
</subsection>
<a name="Session_Bean_Callbacks"/>
<subsection name="Session Bean Callbacks">
<p>
You can define any number of the following callbacks in an session bean by modelling the
appropriate stereotype on an operation. You can only define 1 lifecycle
callback stereotype per session operation. The lifecycle callbacks for a stateless session
bean is a subset of the lifecycle callbacks for a stateful session bean.
</p>
<p>
The following lifecycle callback for <b>stateless</b> session beans and the corresponding stereotype
you need to model are:
<ul>
<li>
PostConstruct - <![CDATA[<<PostConstruct>>]]> - Invoked when the bean is first
created and after the dependency injection is completed.
</li>
<li>
PreDestroy - <![CDATA[<<PreDestroy>>]]> - Invoked when the bean is removed from the
pool or destroyed.
</li>
</ul>
</p>
<p>
The following lifecycle callback for <b>stateful</b> session beans and the corresponding stereotype
you need to model are:
<ul>
<li>
PostConstruct - <![CDATA[<<PostConstruct>>]]> - Invoked when the bean is first
created and after the dependency injection is completed.
</li>
<li>
PreDestroy - <![CDATA[<<PreDestroy>>]]> - Invoked when the bean is removed from the
pool or destroyed.
</li>
<li>
PostActivate - <![CDATA[[<<PostActivate>>]]> - Invoked when the bean has just
been reactivated.
</li>
<li>
PrePassivate - <![CDATA[<<PrePassivate>>]]> - Invoked just before the container
passivates the bean instance.
</li>
</ul>
</p>
<p>
To seperate out the callback for the session bean into an <b>interceptor</b> class, simply model the
<![CDATA[<<Listener>>]]> stereotype on the session bean. This will add the
<code>@Interceptors</code> annotation to the bean base class. The associated listener/interceptor
class includes all the appropriate lifecycle callbacks for the session bean.
The listener is generated on the first run and will never be overwritten, so you are free to add
your implementation to the lifecycle callback operations. These lifecycle methods of the
interceptors must call <code>proceed</code> on the <code>InvocationContext</code> as the last
execution step to invoke the next interceptor in the chain.
</p>
</subsection>
<a name="Message_Driven_Bean_Callbacks"/>
<subsection name="Message-Driven Bean Callbacks">
<p>
You can define any number of the following callbacks in a message-driven bean by modelling the
appropriate stereotype on a MDB operation. You can only define 1 lifecycle
callback stereotype per MDB operation.
</p>
<p>
The following lifecycle callback for <b>stateless</b> session beans and the corresponding stereotype
you need to model are:
<ul>
<li>
PostConstruct - <![CDATA[<<PostConstruct>>]]> - Invoked when the bean is first
created and after the dependency injection is completed.
</li>
<li>
PreDestroy - <![CDATA[<<PreDestroy>>]]> - Invoked when the bean is removed from the
pool or destroyed.
</li>
</ul>
</p>
<p>
You can follow the same process as in <a href="howto14.html#Session_Bean_Callbacks">session bean</a>
callbacks above to separate out the callback interceptor class for the message-driven bean.
</p>
</subsection>
</section>
<section name="Next">
<p>
For a guide on how to utilise transactions in this cartridge, click <a href="howto14.html">here</a>.
</p>
</section>
</body>
</document>
|
