This example application
demonstrates Oracle's support for the EJB
3.0 specification for a Message Driven Bean and
dependency injection of EJBContext and creation of a Timer from the injected EJBContext.
EJB 3.0 greatly simplifies the development of
EJBs, removing many complex development tasks. For an MDB,
the bean class do not have
to implement the javax.ejb.MessageDrivenBean interface and do not have to implement the lifecycle methods and you longer require a deployment descriptor to specify the message destination and factory information.
The following
is the bean class for the MessageLogger
MDB.
Note that this is a pure Java class and
@MessageDriven(
activationConfig = {
@ActivationConfigProperty(propertyName="connectionFactoryJndiName",propertyValue="jms/TopicConnectionFactory"),
@ActivationConfigProperty(propertyName="destinationName", propertyValue="jms/demoTopic"),
@ActivationConfigProperty(propertyName="destinationType", propertyValue="javax.jms.Topic"),
@ActivationConfigProperty(propertyName="messageSelector", propertyValue="RECIPIENT = 'MDB'")
}
)
public class MessageLogger implements TimedObject
{
@Resource javax.ejb.MessageDrivenContext mc;
public void onMessage(Message message)
{
System.out.println("onMessage() - " + message);
try
{
String subject = message.getStringProperty("subject");
String inmessage = message.getStringProperty("message");
TimerService ts = mc.getTimerService();
Timer timer = ts.createTimer(30000, subject);
}
...
Note that the bean uses
the @MessageDriven annotation
to mark the bean as a Stateless EJB.
@ActivationConfig can
be used to specify the various messaging system properties like the message destination, type, etc. You can override these properties by specifying these in the deployment descriptor.
Instead of defining a setMessageDrivenContext () method to get the MessageDrivenConext, itis injected by using the @Resource annotation. Then TimerService is invoked from the injected MessageDrivenContext to create a Timer.
Sample
JMS Client
The Sample JMS client uses JMS 1.1 API to send a message to the destination on which the MDB is listening on. The MDB gets activated after the message arrives on the message destination and then creates the timer.
What you need to know
In order to complete the example application, you should
be familiar with the following:
For further information on EJB 3.0, see the following
documents on OTN:
Software
Requirements
This demonstration requires that the following
software components are installed and configured
correctly:
Notations
- %ORACLE_HOME% - The directory where you installed Oracle's EJB 3.0 container.
- %JAVA_HOME% - The directory where your JDK is installed
- %HOWTO_HOME% - The directory where this demo is unzipped
Building
the Application
The Javadoc
The
To run the sample application on a standalone instance
of OracleAS EJB 3.0 Container, follow these steps:
1. Examine
the Sample File Directories
- build - temporary directory created during the build
- log - temporary directory holding build/deploy logs
- etc - all necessary files to package the application
- lib - holds the application archives that could be deployed
- doc - the How-to document and Javadoc's
- javadoc - the javadoc of the different source files
- how-to-ejb30-mdb.html - this How-to page
- src - the source of the demo
- ejb - contains the sample MDB code
- client - contains application client code
2. Configure the Environment
Ensure
the following environment variables are defined:
- %ORACLE_HOME% - The directory where you installed OC4J.
- %JAVA_HOME% - The directory where you installed
the JDK
- %PATH% - includes %ORACLE_HOME% /ant/bin
3. Start the Server
An Oracle Application Server 10g 10.1.3 must
be running. Start the
container using the following command:
4. Generate, Compile,
and Deploy the Application
Ensure $ORACLE_HOME/ant/bin is included in your PATH environment variable. On some operating systems, Ant does not currently
support the use of environment variables. If this is the case for your operating
system, please modify the common.xml file located in the
%HOWTO_HOME% directory.
Edit ant-oracle.properties (in the demo directory) and
- oc4j.host: host where
OC4J is running
- oc4j.admin.port: RMI port number
(default 23791)
- oc4j.admin.user: admin user name (default oc4jadmin)
- oc4j.admin.password: admin user password (default welcome)
- oc4j.binding.module: website name where deployed web modules
are bound (default http-web-site)
To build the application, type the following command
from the %HOWTO_HOME% directory:
ant
You should now have the newly created ejb30mdb.ear in your
%HOWTO_HOME%/lib directory.
This command would also attempt to deploy the application if the build is
successful. It will first test whether OC4J is running.
Note that you can also deploy the application
separately .
Ensure the %ORACLE_HOME% environment variable is defined,
and from the %HOWTO_HOME%
directory, type the command:
ant deploy
5. Run
the Application
Run
the sample by providing the following command, including a name as the program
argument:
ant run
Return
Summary
In this document, you should have learned how to:
- Develop a Simple Message Driven Bean using EJB
3.0 and how to use dependency injection to inject EJBContext
- Deploy a Simple MDB in
the Oracle Application Server 10g 10.1.3 container
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