O'Reilly - Java Message Service

Java Message Service
JMS provides an ExceptionListener interface for trapping a lost connection and notifying
the client of this condition. The ExceptionListener is bound to the connection - unlike
MessageListeners, which are bound to sessions. The definition of the ExceptionListener
is:
public interface ExceptionListener{
void onException(JMSException exception);
}
It is the responsibility of the JMS provider to call the onException( ) method of all
registered ExceptionListeners after making reasonable attempts to reestablish the
connection automatically. The JMS client can implement the ExceptionListener so that it
can be alerted to a lost connection, and possibly attempt to reestablish the connection
manually.
How can the JMS provider call an ExceptionListener if the client has been disconnected?
Every JMS provider has some amount of functionality that resides in the client application.
We have been referring to this as the client runtime portion of the JMS provider. It is the
responsibility of the client runtime to detect the loss of connection and call the
ExceptionListener.
6.5.1 The Wholesaler Becomes an ExceptionListener
To make our Wholesaler into an ExceptionListener, we start by changing the formal
declaration of the class to implement the javax.jms.ExceptionListener interface:
public class Wholesaler implements
javax.jms.MessageListener,
javax.jms.ExceptionListener
{
...
Next, we remove the connection setup information from the constructor and isolate it in its
own method, establishConnection( ):
public Wholesaler(String broker, String username, String password){
mBroker = broker;
mUsername = username;
mPassword = password;
}
establishConnection( broker, username, password );
establishConnection( ) sets up the connection, the publisher, and the subscriber. The new
addition is the retry logic on the TopicConnectionFactory's createTopicConnection( )
method, which continually retries the connection every ten seconds until it is established:
private void establishConnection(String broker, String username,
String password)
{
...
while (connect == null)
{
try {
connect =
factory.createTopicConnection (username, password);
} catch (javax.jms.JMSException jmse)
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