A simple pattern for implementing Asynchronous Jobs using JMS queues on JBoss

1. EJB3.0 Patterns
Asynchronous EJB3.1 Web Services using JMS
Queues
Michael Mountrakis mountrakis@uit.gr
Unified IT Services http:www.uit.gr

2. The problem
My company decided to migrate to EJB an old legacy
asynchronous application. The requirements are:
● Re – use legacy code from the application
● Define EJB3 design that :
● Employ Jboss Web Service calls to order requests and
monitor their status
● Employ a JMS Queue that will handle and process
requests on a strict order
● Employ a Jboss service to receive a callback from the
JMS queue when processing is finished.
Unified IT Services http:www.uit.gr

3. Comply with EJB3.0 standards
● Use J2EE annotations instead of XML
deployment descriptors
● Do not use threads
● Do not use I/O
● Benefit from EJB3.0 offered Jboss resources,
like Pojo Services, JMX platform....
Unified IT Services http:www.uit.gr

4. Design Synopsis
● Design a Web Service to offer clients the ability to:
to create requests and monitor request status
● Design a Jboss JMS Queue that will process WS
calls and handle the processing status. Processing
is taking place in strict order.
● Design a Web Service that will be called from the
JMS queue when request processing is finished.
Unified IT Services http:www.uit.gr

5. Interfaces – Requests Web Service
Clients can order jobs and monitor their request
@Remote
public interface RequestProxyRemote {
int processAsynch(String inData);
String processStatus(int jobId);
}
Unified IT Services http:www.uit.gr

6. Interfaces – Results Web Service
This Web Service is called when the JMS queue
finishes with a request. This web service has remote
interface:
@Local
public interface ResultsProxyRemote {
void processResults(int jobId, String results);
}
Unified IT Services http:www.uit.gr

7. Unified IT Services http:www.uit.gr

8. Implementation: Requests Web
Service
@Stateless
@Remote(RequestProxyRemote.class)
@WebService
@SOAPBinding(style = Style.RPC)
public class RequestsProxyWS implements ProxyLocal,
RequestProxyRemote {
@Resource
private SessionContext jndiContext;
private ConnectionFactory connectionFactory = null;
private Connection connection = null;
private Session session = null;
private MessageProducer producer = null;
private Queue queue = null;
private StreamMessage OutgoingMsg = null;
Unified IT Services http:www.uit.gr

9. Implementation: JMS Queue
@MessageDriven(activationConfig = {
@ActivationConfigProperty(propertyName = "destinationType",
propertyValue = "javax.jms.Queue"),
@ActivationConfigProperty(propertyName = "destination",
propertyValue = RequestsProcessorMDB.QUEUE_NAME) })
public class RequestsProcessorMDB implements MessageListener {
public static final String QUEUE_NAME =
"queue/tutorial/example";
private static HashMap<Integer,String> map = new
HashMap<Integer,String>();
Unified IT Services http:www.uit.gr

10. Implementation: JMS Queue
public void onMessage(Message msg) {
StreamMessage Smsg = null;
try {
Smsg = (StreamMessage) msg;
/* Acknowledge message */
msg.acknowledge();
Integer key = Smsg.readInt();
String data = Smsg.readString();
Cntext jndiContext = new InitialContext();
ResultsProxyRemote resultsRemote = (ResultsProxyRemote)
jndiContext.lookup(ResultsProxyWS.JNDI_REMOTE);
resultsRemote.processResults(key, results);
} catch (Throwable te) {
}
}
Unified IT Services http:www.uit.gr

11. Implementation: Results Service
@Stateless
@Remote(ResultsProxyRemote.class)
@RemoteBinding(jndiBinding=ResultsProxyWS.JNDI_REMOTE)
@WebService
@SOAPBinding(style = Style.RPC)
public class ResultsProxyWS implements ProxyLocal,
ResultsProxyRemote {
public static final String JNDI_NAME = "ResultsProxyWS";
public static final String JNDI_REMOTE = JNDI_NAME +
"/remote";
@WebMethod
@Override
public void processResults(@WebParam(name = "jobId") int
jobId,
@WebParam(name = "results") String
results) {
System.out.println("processResults() -> got result:" +
results);
}
} Unified IT Services http:www.uit.gr

12. QUEUE Deployment Descriptor for
JBOSS
File: queue-example-service.xml
<?xml version="1.0" encoding="UTF-8"?>
<server>
<mbean code="org.jboss.mq.server.jmx.Queue"
name="jboss.mq.destination:service=Queue,name=tutorial">
<attribute
name="JNDIName">queue/tutorial/example</attribute>
<depends optional-attribute-
name="DestinationManager">jboss.mq:service=DestinationManager</d
epends>
</mbean>
</server>
This must be deployed once to the JBOSS deployment directory
Unified IT Services http:www.uit.gr