7.2. Using a Custom Destination Resolver
Overview
Destination resolvers are a part of the JMS technology Red Hat JBoss Fuse inherits from the Spring Framework. They convert string destination names into JMS
Destination objects. For example, if you specify an endpoint's destination using the destinationName attribute, the endpoint will use a destination resolver to get the appropriate JMS Destination object. Destination resolvers are also used if a destination chooser returns a string and not a JMS Destination object.
Red Hat JBoss Fuse JMS endpoints default to using the
DynamicDestinationResolver destination resolver provided by the Spring Framework. This destination resolver uses the standard JMS Session.createTopic() and Session.createQueue() methods to resolve destination names.
Red Hat JBoss Fuse JMS endpoints can also use the Spring Framework's
JndiDestinationResolver destination resolver. This destination resolver uses the string destination name to perform a JNDI lookup for the JMS destination. If JMS destination is not returned from the JNDI lookup, the resolver resorts to dynamically resolving the destination name. For information on configuring and endpoint to use the JndiDestinationResolver destination resolver. See the section called “Configuring an endpoint to use a destination resolver”.
Implementing a destination resolver
Destination resolvers implement the
org.springframework.jms.support.destination.DestinationResolver interface. The interface has a single method: resolveDestinationName().
The
resolveDestinationName() method, whose signature shown in Example 7.5, “Destination Resolver Method”, takes three parameters: a JMS session, a destination name, and a boolean specifying if the destination is a JMS topic.[1] It returns a JMS destination that correlates to the provided destination name.
Example 7.5. Destination Resolver Method
Destination resolveDestinationName(Session session,
String destinationName,
boolean pubSubDomain)
throws JMSException;
Example 7.6, “Simple Destination Resolver” shows a simple destination resolver implementation.
Example 7.6. Simple Destination Resolver
package com.widgetVendor.example;
import org.springframework.jms.support.destination.DestinationResolver;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Session;
public class widgetDestinationResolver implements DestinationResolver
{
public Destination resolveDestinationName(Session session,
String destinationName,
boolean pubSubDomain)
throws JMSException
{
if (pubSubDomain)
{
return session.createTopic(destinationName);
}
else
{
return session.createQueue(destinationName);
}
}
}Configuring an endpoint to use a destination resolver
You can configure an endpoint to use a custom destination resolver in one of two ways. The recommended way is to configure the destination resolver as a bean and have the endpoint reference the destination resolver's bean. The other way is to explicitly include the destination resolver's configuration as a child of the endpoint.
As shown in Example 7.7, “Configuring a Destination Resolver with a Bean Reference”, configuring an endpoint's destination resolver using a bean reference is a two step process:
- Configure a
beanelement for your destination resolver. - Add a
destinationResolverattribute that references the destination resolver's bean to your endpoint.
Example 7.7. Configuring a Destination Resolver with a Bean Reference
<beans xmlns:jms="http://servicemix.apache.org/jms/1.0"
... >
...
<jms:consumer service="my:widgetService"
endpoint="jbiWidget"
destinationName="widgetQueue"
connectionFactory="#connectionFactory"
destinationResolver="#widgetDestinationResolver" />
<bean id="widgetDestinationResolver"
class="com.widgetVendor.example.widgetDestinationResolver" />
...
</beans>
Example 7.8, “Explicitly Configuring a Destination Resolver” shows an example configuration using the
jms:destinationResolver element. This method is less flexible than the recommended method because other endpoints cannot reuse the destination resolver's configuration.
Example 7.8. Explicitly Configuring a Destination Resolver
<beans xmlns:jms="http://servicemix.apache.org/jms/1.0"
... >
...
<jms:consumer service="my:widgetService"
endpoint="jbiWidget"
destinationName="widgetQueue"
connectionFactory="#connectionFactory">
<jms:destinationResolver>
<bean id="widgetDestinationResolver"
class="com.widgetVendor.example.widgetDestinationResolver" />
</jms:destinationChooser>
</jms:consumer>
...
</beans>