JMS Listener

In this article i would like to focus on the message driven bean for activemq.

Prerequisite:

1. ActiveMq server should be running.
2. Configure you your topic/queue in the console there 
• http://localhost:8161/admin

    3. Configure your application server with activeMQ  resource adapter. e.g. Wildfly module  should         be extracted in wildfly modules directory and same should be configured inside stadalone-                   full.xml.

<subsystem xmlns="urn:jboss:domain:resource-adapters:2.0">
            <resource-adapters>
                <resource-adapter id="activemq-rar.rar">
                    <module slot="main" id="org.apache.activemq"/>
                    <transaction-support>XATransaction</transaction-support>
                    <config-property name="ServerUrl">
                        tcp://localhost:61616
                    </config-property>
                    <config-property name="UserName">
                        defaultUser
                    </config-property>
                    <config-property name="UseInboundSession">
                        false
                    </config-property>
                    <config-property name="Password">
                        defaultPassword
                    </config-property>
                    <connection-definitions>
                        <connection-definition class-name="org.apache.activemq.ra.ActiveMQManagedConnectionFactory" jndi-name="java:/ConnectionFactory" enabled="true" pool-name="ConnectionFactory">
                            <xa-pool>
                                <min-pool-size>1</min-pool-size>
                                <max-pool-size>20</max-pool-size>
                                <prefill>false</prefill>
                                <is-same-rm-override>false</is-same-rm-override>
                            </xa-pool>
                        </connection-definition>
                    </connection-definitions>
                    <admin-objects>
                        <admin-object class-name="org.apache.activemq.command.ActiveMQTopic" jndi-name="java:jboss/activemq/topic/yourtopic" use-java-context="true" pool-name="hsn18cmstopic">
                            <config-property name="PhysicalName">
                                activemq/topic/yourtopic
                            </config-property>
                        </admin-object>
                    </admin-objects>
                </resource-adapter>
            </resource-adapters>
        </subsystem>



To write your implementation of JMS listener your class should implement the interface MessageListener(javax.jms.MessageListener).

public class YourListener implements MessageListener {


}


You need to specify the activation config parameter inside 'MessageDriven' annotation as follows.

@MessageDriven(activationConfig = {
@ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Topic"),
@ActivationConfigProperty(propertyName = "destination", propertyValue = "suborderupdates"),
@ActivationConfigProperty(propertyName = "useJNDI", propertyValue = "false") })

Override the onMessage method and try to extract the TextMessage from the message by parsing JSON string.


       @Override
public void onMessage(Message message) {

try {
logger.info("event received");
TextMessage textMsg = (TextMessage) message;
textMsg.getJMSType();
Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonElement jelement = parser.parse(textMsg.getText())
.getAsJsonObject();
<T> omsEvent = gson.fromJson(jelement,
<T>.class);
//TODO write your code here
} catch (Exception exception) {
exception.printStackTrace();
}
.
Hence the complete class should be something like

/**
 * 
 */


import java.util.logging.Logger;

import javax.ejb.ActivationConfigProperty;
import javax.ejb.MessageDriven;
import javax.inject.Inject;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.TextMessage;

import com.google.gson.Gson;
import com.google.gson.JsonElement;
import com.google.gson.JsonParser;

/**
 * @author Girish.Yadav
 *
 */
@MessageDriven(activationConfig = {
@ActivationConfigProperty(propertyName = "destinationType", propertyValue = "javax.jms.Topic"),
@ActivationConfigProperty(propertyName = "destination", propertyValue = "suborderupdates"),
@ActivationConfigProperty(propertyName = "useJNDI", propertyValue = "false") })

public class OMSListener implements MessageListener {

private static Logger logger = Logger
.getLogger(OMSListener.class.getName());

@Override
public void onMessage(Message message) {

try {
logger.info("OMS event received");
TextMessage textMsg = (TextMessage) message;
textMsg.getJMSType();
Gson gson = new Gson();
JsonParser parser = new JsonParser();
JsonElement jelement = parser.parse(textMsg.getText())
.getAsJsonObject();
<T> omsEvent = gson.fromJson(jelement,
<T>.class);
//TODO write your code here

} catch (Exception exception) {
exception.printStackTrace();
}

}
}