9.4. Specifying the MDB JMS Provider

Up to this point we have looked at the standard JMS client/server architecture. The JMS specification defines an advanced set of interfaces that allow for concurrent processing of a destination's messages, and collectively this functionality is referred to as application server facilities (ASF). Two of the interfaces that support concurrent message processing, javax.jms.ServerSessionPool and javax.jms.ServerSession, must be provided by the application server in which the processing will occur. Thus, the set of components that make up the JBossMQ ASF involves both JBossMQ components as well as JBoss server components. The JBoss server MDB container utilizes the JMS service's ASF to concurrently process messages sent to MDBs.
The responsibilities of the ASF domains are well defined by the JMS specification and so we won't go into a discussion of how the ASF components are implemented. Rather, we want to discuss how ASF components used by the JBoss MDB layer are integrated using MBeans that allow either the application server interfaces, or the JMS provider interfaces to be replaced with alternate implementations.
Let's start with the org.jboss.jms.jndi.JMSProviderLoader MBean. This MBean is responsible for loading an instance of the org.jboss.jms.jndi.JMSProviderAdaptor interface into the JBoss server and binding it into JNDI. The JMSProviderAdaptor interface is an abstraction that defines how to get the root JNDI context for the JMS provider, and an interface for getting and setting the JNDI names for the Context.PROVIDER_URL for the root InitialContext, and the QueueConnectionFactory and TopicConnectionFactory locations in the root context. This is all that is really necessary to bootstrap use of a JMS provider. By abstracting this information into an interface, alternate JMS ASF provider implementations can be used with the JBoss MDB container. The org.jboss.jms.jndi.JBossMQProvider is the default implementation of JMSProviderAdaptor interface, and provides the adaptor for the JBossMQ JMS provider. To replace the JBossMQ provider with an alternate JMS ASF implementation, simply create an implementation of the JMSProviderAdaptor interface and configure the JMSProviderLoader with the class name of the implementation. We'll see an example of this in the configuration section.
In addition to being able to replace the JMS provider used for MDBs, you can also replace the javax.jms.ServerSessionPool interface implementation. This is possible by configuring the class name of the org.jboss.jms.asf.ServerSessionPoolFactory implementation using the org.jboss.jms.asf.ServerSessionPoolLoader MBean PoolFactoryClass attribute. The default ServerSessionPoolFactory factory implementation is the JBoss org.jboss.jms.asf.StdServerSessionPoolFactory class.

9.4.1. org.jboss.jms.jndi.JMSProviderLoader MBean

The JMSProviderLoader MBean service creates a JMS provider adaptor and binds it into JNDI. A JMS provider adaptor is a class that implements the org.jboss.jms.jndi.JMSProviderAdapter interface. It is used by the message driven bean container to access a JMS service provider in a provider independent manner. The configurable attributes of the JMSProviderLoader service are:
  • ProviderName: A unique name for the JMS provider. This will be used to bind the JMSProviderAdapter instance into JNDI under java:/<ProviderName> unless overridden by the AdapterJNDIName attribute.
  • ProviderAdapterClass: The fully qualified class name of the org.jboss.jms.jndi.JMSProviderAdapter interface to create an instance of.
  • FactoryRef: The JNDI name under which the provider javax.jms.ConnectionFactory will be bound.
  • QueueFactoryRef: The JNDI name under which the provider javax.jms.QueueConnectionFactory will be bound.
  • TopicFactoryRef: The JNDI name under which the javax.jms.TopicConnectionFactory will be bound.
  • Properties: The JNDI properties of the initial context used to look up the factories.

Example 9.13. A JMSProviderLoader for accessing a remote JBossMQ server

<mbean code="org.jboss.jms.jndi.JMSProviderLoader"
       name="jboss.mq:service=JMSProviderLoader,name=RemoteJBossMQProvider">
    <attribute name="ProviderName">RemoteJMSProvider</attribute>
    <attribute name="ProviderUrl"></attribute>
    <attribute name="ProviderAdapterClass">
        org.jboss.jms.jndi.JBossMQProvider
    </attribute>
    <attribute name="FactoryRef">XAConnectionFactory</attribute>
    <attribute name="QueueFactoryRef">XAConnectionFactory</attribute>
    <attribute name="TopicFactoryRef">XAConnectionFactory</attribute>
    <attribute name="Properties>
        java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory
        java.naming.factory.url.pkgs=org.jboss.naming:org.jnp.interfaces
        java.naming.provider.url=jnp://remotehost:1099
    </attribute>
</mbean>
The RemoteJMSProvider can be referenced on the MDB invoker config as shown in the jboss.xml fragment given in Example 9.14, “ A jboss.xml fragment for specifying the MDB JMS provider adaptor”.

Example 9.14.  A jboss.xml fragment for specifying the MDB JMS provider adaptor

<proxy-factory-config>
    <JMSProviderAdapterJNDI>RemoteJMSProvider</JMSProviderAdapterJNDI>
    <ServerSessionPoolFactoryJNDI>StdJMSPool</ServerSessionPoolFactoryJNDI>
    <MaximumSize>15</MaximumSize>
    <MaxMessages>1</MaxMessages>
    <MDBConfig>
        <ReconnectIntervalSec>10</ReconnectIntervalSec>
        <DLQConfig>
            <DestinationQueue>queue/DLQ</DestinationQueue>
            <MaxTimesRedelivered>10</MaxTimesRedelivered>
            <TimeToLive>0</TimeToLive>
        </DLQConfig>
    </MDBConfig>
</proxy-factory-config>
Incidentally, because one can specify multiple invoker-proxy-binding elements, this allows an MDB to listen to the same queue/topic on multiple servers by configuring multiple bindings with different JMSProviderAdapterJNDI settings.
Alternatively, one can integrate the JMS provider using JCA configuration like that shown in Example 9.15, “A jms-ds.xml descriptor for integrating a JMS provider adaptor via JCA”.

Example 9.15. A jms-ds.xml descriptor for integrating a JMS provider adaptor via JCA

<tx-connection-factory>
    <jndi-name>RemoteJmsXA</jndi-name>
    <xa-transaction/>
    <adapter-display-name>JMS Adapter</adapter-display-name>
    <config-property name="JMSProviderAdapterJNDI"
                     type="java.lang.String">RemoteJMSProvider</config-property>
    <config-property name="SessionDefaultType"
                     type="java.lang.String">javax.jms.Topic</config-property>
                
    <security-domain-and-application>JmsXARealm</security-domain-and-application>
</tx-connection-factory>