| = Simple MDB |
| :index-group: JMS and MDBs |
| :jbake-type: page |
| :jbake-status: published |
| |
| Below is a fun app, a chat application that uses JMS. We create a message driven bean, by marking our class with `@MessageDriven`. A message driven bean has some similarities with a stateless session bean, in the part that it is pooled too. |
| |
| Well, lets tell our chat-app to listen for incoming messages. That we do by implementing `MessageListener` and overriding the `onMessage(Message message)`. |
| |
| Then this app "listens" for incoming messages, and the messages picked up are processed by `onMessage(Message message)` method. |
| |
| That finishes our message driven bean implementation. The "processing" part could be anything that fits your business-requirement. |
| |
| In this case, it is to respond to the user. The `respond` method shows how a Message can be sent. |
| |
| == ChatBean |
| |
| [source,java] |
| ---- |
| package org.superbiz.mdb; |
| |
| import javax.annotation.Resource; |
| import javax.ejb.MessageDriven; |
| import javax.jms.Connection; |
| import javax.jms.ConnectionFactory; |
| import javax.jms.DeliveryMode; |
| import javax.jms.JMSException; |
| import javax.jms.Message; |
| import javax.jms.MessageListener; |
| import javax.jms.MessageProducer; |
| import javax.jms.Queue; |
| import javax.jms.Session; |
| import javax.jms.TextMessage; |
| |
| @MessageDriven |
| public class ChatBean implements MessageListener { |
| |
| @Resource |
| private ConnectionFactory connectionFactory; |
| |
| @Resource(name = "AnswerQueue") |
| private Queue answerQueue; |
| |
| public void onMessage(Message message) { |
| try { |
| |
| final TextMessage textMessage = (TextMessage) message; |
| final String question = textMessage.getText(); |
| |
| if ("Hello World!".equals(question)) { |
| |
| respond("Hello, Test Case!"); |
| } else if ("How are you?".equals(question)) { |
| |
| respond("I'm doing well."); |
| } else if ("Still spinning?".equals(question)) { |
| |
| respond("Once every day, as usual."); |
| } |
| } catch (JMSException e) { |
| throw new IllegalStateException(e); |
| } |
| } |
| |
| private void respond(String text) throws JMSException { |
| |
| Connection connection = null; |
| Session session = null; |
| |
| try { |
| connection = connectionFactory.createConnection(); |
| connection.start(); |
| |
| // Create a Session |
| session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); |
| |
| // Create a MessageProducer from the Session to the Topic or Queue |
| MessageProducer producer = session.createProducer(answerQueue); |
| producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT); |
| |
| // Create a message |
| TextMessage message = session.createTextMessage(text); |
| |
| // Tell the producer to send the message |
| producer.send(message); |
| } finally { |
| // Clean up |
| if (session != null) session.close(); |
| if (connection != null) connection.close(); |
| } |
| } |
| } |
| ---- |
| |
| == ChatBeanTest |
| |
| [source,java] |
| ---- |
| package org.superbiz.mdb; |
| |
| import junit.framework.TestCase; |
| |
| import javax.annotation.Resource; |
| import javax.ejb.embeddable.EJBContainer; |
| import javax.jms.Connection; |
| import javax.jms.ConnectionFactory; |
| import javax.jms.JMSException; |
| import javax.jms.MessageConsumer; |
| import javax.jms.MessageProducer; |
| import javax.jms.Queue; |
| import javax.jms.Session; |
| import javax.jms.TextMessage; |
| |
| public class ChatBeanTest extends TestCase { |
| |
| @Resource |
| private ConnectionFactory connectionFactory; |
| |
| @Resource(name = "ChatBean") |
| private Queue questionQueue; |
| |
| @Resource(name = "AnswerQueue") |
| private Queue answerQueue; |
| |
| public void test() throws Exception { |
| EJBContainer.createEJBContainer().getContext().bind("inject", this); |
| |
| |
| final Connection connection = connectionFactory.createConnection(); |
| |
| connection.start(); |
| |
| final Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); |
| |
| final MessageProducer questions = session.createProducer(questionQueue); |
| |
| final MessageConsumer answers = session.createConsumer(answerQueue); |
| |
| |
| sendText("Hello World!", questions, session); |
| |
| assertEquals("Hello, Test Case!", receiveText(answers)); |
| |
| |
| sendText("How are you?", questions, session); |
| |
| assertEquals("I'm doing well.", receiveText(answers)); |
| |
| |
| sendText("Still spinning?", questions, session); |
| |
| assertEquals("Once every day, as usual.", receiveText(answers)); |
| } |
| |
| private void sendText(String text, MessageProducer questions, Session session) throws JMSException { |
| |
| questions.send(session.createTextMessage(text)); |
| } |
| |
| private String receiveText(MessageConsumer answers) throws JMSException { |
| |
| return ((TextMessage) answers.receive(1000)).getText(); |
| } |
| } |
| ---- |
| |
| = Running |
| |
| [source,console] |
| ---- |
| ------------------------------------------------------- |
| T E S T S |
| ------------------------------------------------------- |
| Running org.superbiz.mdb.ChatBeanTest |
| Apache OpenEJB 4.0.0-beta-1 build: 20111002-04:06 |
| http://tomee.apache.org/ |
| INFO - openejb.home = /Users/dblevins/examples/simple-mdb |
| INFO - openejb.base = /Users/dblevins/examples/simple-mdb |
| INFO - Using 'javax.ejb.embeddable.EJBContainer=true' |
| INFO - Configuring Service(id=Default Security Service, type=SecurityService, provider-id=Default Security Service) |
| INFO - Configuring Service(id=Default Transaction Manager, type=TransactionManager, provider-id=Default Transaction Manager) |
| INFO - Found EjbModule in classpath: /Users/dblevins/examples/simple-mdb/target/classes |
| INFO - Beginning load: /Users/dblevins/examples/simple-mdb/target/classes |
| INFO - Configuring enterprise application: /Users/dblevins/examples/simple-mdb |
| WARN - Method 'lookup' is not available for 'javax.annotation.Resource'. Probably using an older Runtime. |
| INFO - Auto-configuring a message driven bean ChatBean destination ChatBean to be destinationType javax.jms.Queue |
| INFO - Configuring Service(id=Default MDB Container, type=Container, provider-id=Default MDB Container) |
| INFO - Auto-creating a container for bean ChatBean: Container(type=MESSAGE, id=Default MDB Container) |
| INFO - Configuring Service(id=Default JMS Resource Adapter, type=Resource, provider-id=Default JMS Resource Adapter) |
| INFO - Configuring Service(id=Default JMS Connection Factory, type=Resource, provider-id=Default JMS Connection Factory) |
| INFO - Auto-creating a Resource with id 'Default JMS Connection Factory' of type 'javax.jms.ConnectionFactory for 'ChatBean'. |
| INFO - Auto-linking resource-ref 'java:comp/env/org.superbiz.mdb.ChatBean/connectionFactory' in bean ChatBean to Resource(id=Default JMS Connection Factory) |
| INFO - Configuring Service(id=AnswerQueue, type=Resource, provider-id=Default Queue) |
| INFO - Auto-creating a Resource with id 'AnswerQueue' of type 'javax.jms.Queue for 'ChatBean'. |
| INFO - Auto-linking resource-env-ref 'java:comp/env/AnswerQueue' in bean ChatBean to Resource(id=AnswerQueue) |
| INFO - Configuring Service(id=ChatBean, type=Resource, provider-id=Default Queue) |
| INFO - Auto-creating a Resource with id 'ChatBean' of type 'javax.jms.Queue for 'ChatBean'. |
| INFO - Configuring Service(id=Default Managed Container, type=Container, provider-id=Default Managed Container) |
| INFO - Auto-creating a container for bean org.superbiz.mdb.ChatBeanTest: Container(type=MANAGED, id=Default Managed Container) |
| INFO - Auto-linking resource-ref 'java:comp/env/org.superbiz.mdb.ChatBeanTest/connectionFactory' in bean org.superbiz.mdb.ChatBeanTest to Resource(id=Default JMS Connection Factory) |
| INFO - Auto-linking resource-env-ref 'java:comp/env/AnswerQueue' in bean org.superbiz.mdb.ChatBeanTest to Resource(id=AnswerQueue) |
| INFO - Auto-linking resource-env-ref 'java:comp/env/ChatBean' in bean org.superbiz.mdb.ChatBeanTest to Resource(id=ChatBean) |
| INFO - Enterprise application "/Users/dblevins/examples/simple-mdb" loaded. |
| INFO - Assembling app: /Users/dblevins/examples/simple-mdb |
| INFO - Jndi(name="java:global/EjbModule1515710343/org.superbiz.mdb.ChatBeanTest!org.superbiz.mdb.ChatBeanTest") |
| INFO - Jndi(name="java:global/EjbModule1515710343/org.superbiz.mdb.ChatBeanTest") |
| INFO - Created Ejb(deployment-id=org.superbiz.mdb.ChatBeanTest, ejb-name=org.superbiz.mdb.ChatBeanTest, container=Default Managed Container) |
| INFO - Created Ejb(deployment-id=ChatBean, ejb-name=ChatBean, container=Default MDB Container) |
| INFO - Started Ejb(deployment-id=org.superbiz.mdb.ChatBeanTest, ejb-name=org.superbiz.mdb.ChatBeanTest, container=Default Managed Container) |
| INFO - Started Ejb(deployment-id=ChatBean, ejb-name=ChatBean, container=Default MDB Container) |
| INFO - Deployed Application(path=/Users/dblevins/examples/simple-mdb) |
| Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.547 sec |
| |
| Results : |
| |
| Tests run: 1, Failures: 0, Errors: 0, Skipped: 0 |
| ---- |