Today I am going to share how to run a sample program to send and receive messages to a JMS Queue .
So first lets brief you about JMS .
What Is Messaging?
Messaging is a method of communication between software components or applications. A messaging client can send messages to, and receive messages from, any other client. Each client connects to a messaging agent that provides facilities for creating, sending, receiving, and reading messages.
What Is the JMS API?
The Java Message Service is a Java API that allows applications to create, send, receive, and read messages. Designed by Sun and several partner companies, the JMS API defines a common set of interfaces and associated semantics that allow programs written in the Java programming language to communicate with other messaging implementations.
For more details on JMS specification read here .
Pre requisites for this java exercise :
1. Install Oracle Weblogic Server 12.1.3 is preferred since this exercise has been done with WLS 12.1.3.
2. Create a domain on the WLS and a managed_server to deploy applications , target the JMS modules .
3. Your admin server , managed server should be up and running .
Configuration
1. Create a JMS Server :
A JMS server acts as a management container for resources within JMS modules. Some of its responsibilities include the maintenance of persistence and state of messages and subscribers. A JMS server is required in order to create a JMS module.
-> Services > Messaging > JMS Servers
Select New
Name : testJMSServer
Persistent Store: (none) -> Next
Target : managed_server-1 [The managed Server created and configured in your Oracle WLS_Server]
Finish
-------------------------------------------------------------------------------------------------------------------------
The JMS server should now be visible in the list with Health OK.
2. Create a JMS Module
A JMS module is a definition which contains JMS resources such as queues and topics. A JMS module is required in order to create a JMS queue.
-> Services > Messaging > JMS Modules -> New
Name: testJMSModule -> Leave the other options empty -> Next
-> Targets: managed_server- 1 (or choose the same one as the JMS server)
-> Leave “Would you like to add resources to this JMS system module” unchecked and press Finish
3. Create a Connection Factory
A connection factory is a resource that enables JMS clients to create connections to JMS destinations.
-> Services > Messaging > JMS Modules
-> select testJMSModule and click New
-> Select Connection factory -> Next
-> Name: testConnectionFactory , JNDI Name : jms/testcf
-> Leave the other values at default
-> Advanced Targeting -> Subdeployments -> Click Create a new Sub deployment
A subdeployment is a mechanism by which JMS resources are grouped and targeted to a server instance or a cluster .
Subdeployment Name : testJMSSubdeployment -> OK
On Tagets -> check managed_server-1 and testJMSServer or the corresponding names you have used in this exercise.
4. Create a JMS Queue
A JMS queue (as opposed to a JMS topic) is a point-to-point destination type. A message is written to a specific queue or received from a specific queue.
-> Services > Messaging > JMS Modules
-> select testJMSModule and click New
-> Select Queue -> Next
-> Name: testQueue , JNDI Name : jms/testq
-> Template : None
-> Subdeployments -> testJMSSubdeployment -> OK
On Tagets -> check testJMSServer.
Finish
You should see the following resources under testJMSModule under Services -> Messaging -> JMS Modules
The JMS queue is now complete and can be accessed using the JNDI names
jms/testcf
jms/testq
If you hit exception :
Workaround :
- create jms queue without subdeployment specified and save
- edit queue and then set subdeployment then save
5. Let's come to coding part .
I am showing the simplest way possible to do this exercise hence I will be creating a Java Project TestJMS , create a package named jms.test in a src directory , create a folder in this project called lib .
Now under your Oracle_Home which would look like this C:\OracleHome may be different for you ; this is the root directory from where you go and run your weblogic scripts etc.
-> Under OracleHome -> wlsserver -> modules -> copy all jars(*.jar) and paste in under the lib , also OracleHome -> wlsserver -> server -> lib -> copy all jars(*.jar) and paste in under the lib .
Create three class files under this package MyListener.java , MyReceiver.java and MySender.java
The following is the source code and I am explaining the code in the comments section in the code itself , have a look .
/**
* This example shows how to establish a connection and send messages to the JMS
* queue. The classes in this package operate on the same JMS queue. Run the
* classes together to see the messages being sent and received.
* @author Anmol Deep
*/
MySender.java
package jms.test;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Hashtable;
import java.util.Properties;
import javax.jms.JMSException;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueSender;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
/**
* The class is used to send messages to the queue.
*/
public class MySender {
// Defines the JNDI context factory.
public final static String JNDI_FACTORY = "weblogic.jndi.WLInitialContextFactory";
// Defines the Connection Factory's JNDI name
public final static String JMS_FACTORY = "jms/testcf";
// Defines the queue's JNDI name
public final static String QUEUE = "jms/testq";
private QueueConnectionFactory qconFactory;
private QueueConnection qcon;
private QueueSession qsession;
private QueueSender qsender;
private Queue queue;
private TextMessage msg;
public void init(Context ctx, String queueName) throws NamingException,
JMSException {
// Create the QueueConnectioFactory by lookup JNDI name
qconFactory = (QueueConnectionFactory) ctx.lookup(JMS_FACTORY);
// Create the Queue Connection
qcon = qconFactory.createQueueConnection();
// Create the QueueSession
qsession = qcon.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);
// Create the Queue object by lookup JNDI name
queue = (Queue) ctx.lookup(queueName);
// Create the QueueSender object
qsender = qsession.createSender(queue);
// Create the TextMessage Object
msg = qsession.createTextMessage();
// Start the Queue Connection
qcon.start();
}
/**
* Sends a message to a JMS queue.
*
* @param message
* message to be sent
* @exception JMSException
* if JMS fails to send message due to internal error
*/
public void send(String message) throws JMSException {
msg.setText(message);
qsender.send(msg);
}
/**
* Closes JMS objects.
*
* @exception JMSException
* if JMS fails to close objects due to internal error
*/
public void close() throws JMSException {
qsender.close();
qsession.close();
qcon.close();
}
/**
* main() method.
*
* @exception Exception
* if operation fails
*/
public static void main(String[] args) throws Exception {
Properties parm = new Properties();
parm.setProperty(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
// weblogic managed server URL
parm.setProperty(Context.PROVIDER_URL, "t3://localhost:7002");
parm.setProperty("java.naming.security.principal", "weblogicUserName");
parm.setProperty("java.naming.security.credentials", "weblogicPassword");
Context ctx = new InitialContext(parm);
ctx.lookup(QUEUE);
MySender qs = new MySender();
qs.init(ctx, QUEUE);
readAndSend(qs);
qs.close();
}
private static void readAndSend(MySender mySender) throws IOException,
JMSException {
BufferedReader msgStream = new BufferedReader(new InputStreamReader(
System.in));
String text= null;
boolean quitting = false;
do {
System.out.print("Enter message (\"quit\" to quit): \n");
text= msgStream.readLine();
if (text!= null && text.trim().length() != 0) {
mySender.send(text);
System.out.println("JMS Message Sent: " + text+ "\n");
quitting= text.equalsIgnoreCase("quit");
}
} while (!quitting);
}
}
A
MessageListener object is used to receive asynchronously delivered messages. For more info. read this
MyListener.java
package jms.test;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.TextMessage;
public class MyListener implements MessageListener {
public void onMessage(Message m) {
try{
TextMessage textMessage=(TextMessage)m;
System.out.println("Following Message Receieved :"+textMessage.getText());
}catch(JMSException e){
System.out.println(e);
e.printStackTrace();}
}
}
MyReceiver.java
package jms.test;
import java.util.Properties;
import javax.jms.Queue;
import javax.jms.QueueConnection;
import javax.jms.QueueConnectionFactory;
import javax.jms.QueueReceiver;
import javax.jms.QueueSession;
import javax.jms.Session;
import javax.naming.Context;
import javax.naming.InitialContext;
public class MyReceiver {
public static void main(String[] args) {
try {
Properties parm = new Properties();
parm.setProperty(Context.INITIAL_CONTEXT_FACTORY,
"weblogic.jndi.WLInitialContextFactory");
parm.setProperty(Context.PROVIDER_URL, "t3://localhost:7002");
parm.setProperty("java.naming.security.principal", "weblogicUserName");
parm.setProperty("java.naming.security.credentials", "weblogicPassword");
Context ctx = new InitialContext(parm);
QueueConnectionFactory qconF= (QueueConnectionFactory) ctx
.lookup("jms/testcf");
QueueConnection qCon = qconF.createQueueConnection();
qCon.start();
QueueSession qSess = qCon.createQueueSession(false,
Session.AUTO_ACKNOWLEDGE);
Queue queue = (Queue) ctx.lookup("jms/testq");
QueueReceiver qReceiver = qSess.createReceiver(queue);
// create listener object
MyListener listener = new MyListener();
// register the listener object with receiver
qReceiver.setMessageListener(listener);
System.out.println("Receiver is ready, waiting for messages.");
System.out.println("press Ctrl+c to shutdown...");
while (true) {
Thread.sleep(1000);
}
} catch (Exception e) {
e.printStackTrace();
System.out.println(e);
}
}
}
Run the MySender class
Run the MyReciever class
On Weblogic Under JMSModules - > testJMSModule - > testQueue -> Monitoring tab -> Show Messages
Sample Output :
MySender
Enter message ("quit" to quit):
This is a sample program to Send messages to a JMS Queue
JMS Message Sent: This is a sample program to Send messages to a JMS QueueEnter message ("quit" to quit):
This is the second Message Sent
JMS Message Sent: This is the second Message Sent
Enter message ("quit" to quit):
quit
JMS Message Sent: quit
MyReceiver
Receiver is ready, waiting for messages.
press Ctrl+c to shutdown...Following Message Receieved :This is a sample program to Send messages to a JMS Queue
Following Message Receieved :This is the second Message Sent
Following Message Receieved :"quit"
Following Message Receieved :quit
End of Exercise
Happy Coding .
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