Patterns: Implementing Self-Service in an SOA Environment

Chapter 11. JMS scenario 365

1.1.1) sendActivationMail() invokes sendMail(), passing the text of the

message and e-mail address.

1.1.2) sendMail() creates a connection to the message service provider, a

session for sending and receiving messages, and an empty text

message.

1.1.4) sendMail() sets the text for the message.

1.1.6) sendMail() creates a message producer to create a message.

1.1.8) sendMail() sends the message.

11.3 Applying the design guidelines

In the ITSOMart application, the following applies:

򐂰 The Mail Service Proxy acts as the JMS client.

򐂰 A JMS message of type

text is used to send the e-mail information to the

MailService.

򐂰 The default messaging provider in WebSphere Application Server V6 is used

as the JMS provider.

11.3.1 Point-to-point messaging model

The messaging model used for this example is the JMS point-to-point model. In

this model, a client typically sends a message to a specific queue and receives a

message from a specific queue. The ITSOMart application connects to a single

messaging application at the back-end and therefore point-to-point is the most

suitable model.

The front-end application uses the send-and-forget messaging pattern. The

back-end application uses the message consumer pattern to process requests

and the send-and-forget pattern to deliver the reply.

For further reference on JMS point-to-point and publish/subscribe, refer to the

JMS Specification available at:

http://java.sun.com/products/jms/docs.html

11.3.2 JMS resource lookups using JNDI

The sample application uses a utility class named JNDILookup to look up the

JMS resources. JMSLookup adds some useful functionality, such as caching the

JMS objects references. See Example 11-1 on page 366.

366 Patterns: Implementing Self-Service in an SOA Environment

Example 11-1 JNDI lookup of JMS Connection Factory

/*

* Created on Apr 17, 2005

*/

package com.ibm.patterns.util;

import java.util.HashMap;

import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

/**

* @author sandyg

*

* TODO To change the template for this generated type comment go to

* Window - Preferences - Java - Code Style - Code Templates

*/

public class JNDILookup {

private static JNDILookup instance = new JNDILookup();

private Context ic = null;

private HashMap objectNames=new HashMap();

public static JNDILookup singleton() {

return instance;

}

private void getInitialContext() throws NamingException {

ic = (Context)new InitialContext().lookup("java:comp/env");

}

public Object getJndiObject(String jndiName) throws NamingException{

//Check if object exists in HashMap if so return

Object retreived=null;

if (objectNames.containsKey(jndiName)) {

retreived = objectNames.get(jndiName);

return retreived;

}

//The object was not found, do a lookup

retreived = findObject(jndiName);

return retreived;

}

private Object findObject(String jndiName) throws NamingException{

Object retreived=null;

//hmm.. object was not found, this is the first run we need to lookup

and put in HashMap