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Listener Containers

Both the generic consumer endpoint and the SOAP consumer endpoint use Spring listener containers to handle incoming messages. The listener container handles the details of receiving messages from the destination, participating in transactions, and controlling the threads used to dispatch messages to the endpoint.

Fuse ESB's JMS consumer endpoints support three types of listener containers:

Simple

The simple listener container creates a fixed number of JMS sessions at startup and uses them throughout the lifespan of the container. It cannot dynamically adapt to runtime conditions nor participate in externally managed transactions.

Default

The default listener container provides the best balance between placing requirements on the JMS provider and features. Because of this, it is the default listerner container for Fuse ESB JMS consumer endpoints. The default listener container can adapt to changing runtime demands. It is also capable of participating in externally managed transactions.

Server session

The server session listener container leverages the JMS ServerSessionPool SPI to allow for dynamic management of JMS sessions. It provides the best runtime scaling and supports externally managed transactions. However, it requires that your JMS provider supports the JMS ServerSessionPool SPI.

By default, consumer endpoints use the default listener container. If you want to configure the an endpoint to use a different listener container, you specify that using the endpoint's listenerType attribute. Table 3.1 lists the values for the listenerType attribute.

Table 3.1. Values for Configuring a Consumer's Listener Container

ValueDescription
simple Specifies that the endpoint will use the simple listener container.
default Specifies that the endpoint will use the default listener container.
server Specifies that the endpoint will use the server session listener container.

Example 3.4 shows configuration for SOAP consumer that uses the simple listener container.

Example 3.4. Configuring a SOAP Consumer to Use the Simple Listener Container

<beans xmlns:jms="http://servicemix.apache.org/jms/1.0"
       ... >
  ...
  <jms:soap-consumer wsdl="classpath:widgets.wsdl"
                     destinationName="widgetQueue"
                     connectionFactory="#connectionFactory"
                     listenerType="simple" />
  ...
</beans>

There are several ways of tuning the performance of a generic consumer endpoint or a SOAP consumer endpoint. They are all controlled by the listener container used by the endpoint.

Table 3.2 describes the attributes used to tune endpoint performance.

Table 3.2. Attributes Used to Performance Tune Standard JMS Consumers and SOAP JMS Consumers

AttributeTypeListener(s)DescriptionDefault
cacheLevel intdefaultSpecifies the level of caching allowed by the listener. Valid values are 0(CACHE_NONE), 1(CACHE_CONNECTION), 2(CACHE_SESSION), and 3(CACHE_CONSUMER).0
clientId stringallSpecifies the ID to be used for the shared Connection object used by the listener container.Uses provider assigned ID
concurrentConsumers int

default

simple

Specifies the number of concurrent consumers created by the listener.1
maxMessagesPerTask int

default

server

Specifies the number of attempts to receive messages per task.-1(unlimited)
receiveTimeout longdefaultSpecifies the timeout for receiving a message in milliseconds.1000
recoveryIntervallongdefaultSpecifies the interval, in milliseconds, between attempts to recover after a failed listener set-up.5000

Example 3.5 shows an example of a generic consumer that allows consumer level message caching and only tries once to receive a message.

Example 3.5. Tuning a Generic Consumer Endpoint

<beans xmlns:jms="http://servicemix.apache.org/jms/1.0"
       ... >
  ...
  <jms:consumer service="my:widgetService"
                endpoint="jbiWidget"
                destinationName="widgetQueue"
                connectionFactory="#connectionFactory" 
                cacheLevel="3"
                maxMessagesPerTask="1"/>
  ...
</beans>

The server session listener container uses the JMS ServerSessionPool SPI to tune an endpoint's performance. In order for the listener container to function,k it uses a ServerSessionFactory object. By default, the Fuse ESB JMS BC uses the Spring framework's SimpleServerSessionFactory object. This server session factory creates a new JMS ServerSession object with a new JMS session everytime it is called.

You can configure the endpoint to use a different server session factory using the serverSessionFactory attribute. This attribute provides a reference to the bean configuring the ServerSessionFactory object.

[Note]Note

You can also explicitly configure the endpoint's ServerSessionFactory object by adding a serverSessionFactory child element to the endpoint's configuration. This element would wrap the ServerSessionFactory object's configuration bean.

Example 3.6 shows an example of configuring an endpoint to use the Spring framework's CommonsPoolServerSessionFactory object as a session factory.

Example 3.6. Configuring a Consumer to Use a Pooled Session Factory

<beans xmlns:jms="http://servicemix.apache.org/jms/1.0"
       ... >
  ...
  <jms:consumer service="my:widgetService"
                endpoint="jbiWidget"
                destinationName="widgetQueue"
                connectionFactory="#connectionFactory" 
                listenerType="server"
                serverSessionFactory="#pooledSessionFactory"/>

  <bean id="pooledSessionFactory"
         class="org.springframework.jms.listener.serversession.CommonsPoolServerSessionFactory" />
  ...
</beans>

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