Patterns: Broker Interactions for Intra- and Inter-enterprise

262 Broker Interactions for Intra- and Inter-enterprise

9.7 Developing real-time message flows

Real-time flows allow JMS clients to publish and retrieve topic information using

TCP/IP. The following steps outline the development process and guidelines for

developing a simple real-time message flow.

9.7.1 Prepare the subscriber applications

In order to retrieve topic information, the application implements a

message-driven bean.

Create the message-driven bean

Example 9-2 shows a simple message-driven bean that takes topic information

and prints it to the console.

Example 9-2 Message-driven bean

package eb;

import javax.jms.JMSException;

import javax.jms.TextMessage;

/**

* Bean implementation class for Enterprise Bean: Wholesale

*/

public class WholesaleBean

implements javax.ejb.MessageDrivenBean, javax.jms.MessageListener {

private javax.ejb.MessageDrivenContext fMessageDrivenCtx;

/**

* getMessageDrivenContext

*/

public javax.ejb.MessageDrivenContext getMessageDrivenContext() {

return fMessageDrivenCtx;

}

/**

* setMessageDrivenContext

*/

public void setMessageDrivenContext(javax.ejb.MessageDrivenContext ctx) {

fMessageDrivenCtx = ctx;

}

/**

* ejbCreate

*/

public void ejbCreate() {

}

/**

* onMessage

Chapter 9. Broker solutions using WebSphere Business Integration Message Broker 263

*/

public void onMessage(javax.jms.Message msg) {

try {

TextMessage textMessage = (TextMessage)msg;

System.out.println("Message: "+textMessage.getText());

} catch (Exception e) {

System.out.println(e.getMessage());

e.printStackTrace();

}

}

/**

* ejbRemove

*/

public void ejbRemove() {

}

}

Figure 9-32 shows the EJB deployment descriptor characteristics for the

message-driven bean.

Figure 9-32 WebSphere bindings for the message-driven bean

When you deploy the application, you will need to bind the bean to the message

listener port. The application developer can set the default binding in WebSphere

Studio in the EJB deployment descriptor using the Listener Port Name field in the

Beans tab. The setting is stored in the META-INF/ibm-ejb-jar-bnd.xmi file. The

administrator can override this at install time.

264 Broker Interactions for Intra- and Inter-enterprise

Deployment considerations

The use of a message-driven bean necessitates the definition of JMS resources

to the server. You will need the following components:

򐂰 A topic connection factory

򐂰 A topic destination

򐂰 A listener port

For our example, these are defined using the WebSphere administrative console

in the following way:

1. Select Resources -> WebSphere MQ JMS Provider.

2. The first thing you need is a topic connection factory. Select WebSphere MQ

Topic Connection Factories in the Additional Properties table.

3. Click New and enter the following attributes and click OK:

– Name: WholesaleTCF_EB_IP

– JNDI Name: jms/eb/ip/WholesaleTCF

– Host: ip_address_of_EventBroker (kaa5070)

– Port: ip_port_of_EventBroker (7081)

– Transport Type: DIRECT

– Broker Version: Advanced

– XA Enabled: false

4. Select WebSphere MQ Topic Destinations and click New. Enter the

following attributes and click OK.

– Name: SalesForecast_EB_IP

– JNDI Name: jms/eb/ip/SalesForecast

– Base Topic Name: SalesForecast_EB_IP

5. Select Servers in the navigation bar and select your server.

6. Select Message Listener Service in the Additional Properties table.

7. Click Listener Ports.

8. Click New, enter the following attributes and click OK.

– Name: SalesForecastLP_EB_IP

– Connection Factory JNDI name: jms/eb/ip/WholesaleTCF

– Destination JNDI name: jms/eb/ip/SalesForecast

9. Select Application Servers > whostx > Message Listener Service >

Custom Properties and set the following parameters:

– Name: non.asf.receive.timeout

– Value: >0 (for example: 5000)

10.Save the configuration and restart the server.

Chapter 9. Broker solutions using WebSphere Business Integration Message Broker 265

When you install the application, make sure that you bind the listener port to the

message-driven bean.

9.7.2 Prepare the publisher application

Example 9-3 shows a simple servlet that can be used to publish information to a

topic. The input to the servlet includes the following parameters:

򐂰 host: The host IP address of the broker

򐂰 port: The port number for the Real-timeOptimizedFlow node

򐂰 topic: The pub/sub topic. This must match the topic specified as the base

topic name in the target application’s topic destination definition.

򐂰 message: The information to publish.

Example 9-3 Publishing to a topic

import java.io.IOException;

import javax.jms.JMSException;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.jms.Topic;

import javax.jms.TopicConnection;

import javax.jms.TopicPublisher;

import javax.jms.TopicSession;

import javax.servlet.Servlet;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.ibm.mq.jms.MQTopicConnectionFactory;

/**

* @version 1.0

* @author

*/

public class TestEB extends HttpServlet implements Servlet {

/**

* @see javax.servlet.http.HttpServlet#void (javax.servlet.http.HttpServletRequest,

javax.servlet.http.HttpServletResponse)

*/

public void doGet(HttpServletRequest req, HttpServletResponse resp)

throws ServletException, IOException {

266 Broker Interactions for Intra- and Inter-enterprise

try {

String host = req.getParameter("host");

int port = Integer.parseInt(req.getParameter("port"));

String topicName = req.getParameter("topic");

String message = req.getParameter("message");

MQTopicConnectionFactory mqtcf = new MQTopicConnectionFactory();

mqtcf.setHostName(host);

mqtcf.setPort(port);

mqtcf.setTransportType(com.ibm.mq.jms.JMSC.MQJMS_TP_DIRECT_TCPIP);

// Create a topic connection

TopicConnection conn = mqtcf.createTopicConnection();

// Don't forget to start the connection

conn.start();

// Create a topic session from the connection

TopicSession sess = conn.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);

// Create the Topic

Topic t = sess.createTopic(topicName);

// Now that we have the Topic, we can start the main loop of the

// program, remembering to create either the TopicPublisher or the

// TopicSubscriber on the first run round the loop

TopicPublisher pub = sess.createPublisher(t);

TextMessage msg = sess.createTextMessage();

// ...set the message content...

msg.setText(message);

// ...and publish it

pub.publish(msg);

System.out.println("Message published");

pub.close();

sess.close();

conn.close();

} catch (NumberFormatException e) {

System.out.println(e.getMessage());

e.printStackTrace();

} catch (JMSException e) {

e.printStackTrace();

e.printStackTrace();

}