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23. JMS (Java Message Service)
Spring provides a JMS integration framework that simplifies the use of the JMS API much
like Spring’s integration does for the JDBC API.
JMS can be roughly divided into two areas of functionality, namely the production and
consumption of messages. The JmsTemplate class is used for message production and
synchronous message reception. For asynchronous reception similar to Java EE’s
message-driven bean style, Spring provides a number of message listener containers that
are used to create Message-Driven POJOs (MDPs).
The package org.springframework.jms.core provides the core functionality for using
JMS. It contains JMS template classes that simplify the use of the JMS by handling the
creation and release of resources, much like the JdbcTemplate does for JDBC. The
design principle common to Spring template classes is to provide helper methods to
perform common operations and for more sophisticated usage, delegate the essence of the
processing task to user implemented callback interfaces. The JMS template follows the
same design. The classes offer various convenience methods for the sending of messages,
consuming a message synchronously, and exposing the JMS session and message producer to
the user.
The package org.springframework.jms.support provides JMSException translation
functionality. The translation converts the checked JMSException hierarchy to a
mirrored hierarchy of unchecked exceptions. If there are any provider specific
subclasses of the checked javax.jms.JMSException , this exception is wrapped in the
unchecked UncategorizedJmsException .
The package org.springframework.jms.support.converter provides a MessageConverter
abstraction to convert between Java objects and JMS messages.
The package org.springframework.jms.support.destination provides various strategies
for managing JMS destinations, such as providing a service locator for destinations
stored in JNDI.
Finally, the package org.springframework.jms.connection provides an implementation of
the ConnectionFactory suitable for use in standalone applications. It also contains an
implementation of Spring’s PlatformTransactionManager for JMS (the cunningly named
JmsTransactionManager ). This allows for seamless integration of JMS as a transactional
resource into Spring’s transaction management mechanisms.
The JmsTemplate class is the central class in the JMS core package. It simplifies the
use of JMS since it handles the creation and release of resources when sending or
synchronously receiving messages.
Code that uses the JmsTemplate only needs to implement callback interfaces giving them
a clearly defined high level contract. The MessageCreator callback interface creates a
message given a Session provided by the calling code in JmsTemplate . In order to
allow for more complex usage of the JMS API, the callback SessionCallback provides the
user with the JMS session and the callback ProducerCallback exposes a Session and
MessageProducer pair.
The JMS API exposes two types of send methods, one that takes delivery mode, priority,
and time-to-live as Quality of Service (QOS) parameters and one that takes no QOS
parameters which uses default values. Since there are many send methods in
JmsTemplate , the setting of the QOS parameters have been exposed as bean properties to
avoid duplication in the number of send methods. Similarly, the timeout value for
synchronous receive calls is set using the property setReceiveTimeout .
Some JMS providers allow the setting of default QOS values administratively through the
configuration of the ConnectionFactory. This has the effect that a call to
MessageProducer 's send method send(Destination destination, Message message) will
use different QOS default values than those specified in the JMS specification. In order
to provide consistent management of QOS values, the JmsTemplate must therefore be
specifically enabled to use its own QOS values by setting the boolean property
isExplicitQosEnabled to true .
![[Note]](images/note.png) | Note |
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Instances of the JmsTemplate class are thread-safe once configured. This is
important because it means that you can configure a single instance of a JmsTemplate
and then safely inject this shared reference into multiple collaborators. To be
clear, the JmsTemplate is stateful, in that it maintains a reference to a
ConnectionFactory , but this state is not conversational state.
|
The JmsTemplate requires a reference to a ConnectionFactory . The ConnectionFactory
is part of the JMS specification and serves as the entry point for working with JMS. It
is used by the client application as a factory to create connections with the JMS
provider and encapsulates various configuration parameters, many of which are vendor
specific such as SSL configuration options.
When using JMS inside an EJB, the vendor provides implementations of the JMS interfaces
so that they can participate in declarative transaction management and perform pooling
of connections and sessions. In order to use this implementation, Java EE containers
typically require that you declare a JMS connection factory as a resource-ref inside
the EJB or servlet deployment descriptors. To ensure the use of these features with the
JmsTemplate inside an EJB, the client application should ensure that it references the
managed implementation of the ConnectionFactory .
Caching Messaging Resources
The standard API involves creating many intermediate objects. To send a message the
following API walk is performed
ConnectionFactory->Connection->Session->MessageProducer->send
Between the ConnectionFactory and the Send operation there are three intermediate
objects that are created and destroyed. To optimise the resource usage and increase
performance two implementations of IConnectionFactory are provided.
Spring provides an implementation of the ConnectionFactory interface,
SingleConnectionFactory , that will return the same Connection on all
createConnection() calls and ignore calls to close() . This is useful for testing and
standalone environments so that the same connection can be used for multiple
JmsTemplate calls that may span any number of transactions. SingleConnectionFactory
takes a reference to a standard ConnectionFactory that would typically come from JNDI.
The CachingConnectionFactory extends the functionality of SingleConnectionFactory
and adds the caching of Sessions, MessageProducers, and MessageConsumers. The initial
cache size is set to 1, use the property SessionCacheSize to increase the number of
cached sessions. Note that the number of actual cached sessions will be more than that
number as sessions are cached based on their acknowledgment mode, so there can be up to
4 cached session instances when SessionCacheSize is set to one, one for each
AcknowledgementMode. MessageProducers and MessageConsumers are cached within their
owning session and also take into account the unique properties of the producers and
consumers when caching. MessageProducers are cached based on their destination.
MessageConsumers are cached based on a key composed of the destination, selector,
noLocal delivery flag, and the durable subscription name (if creating durable consumers).
23.2.3 Destination Management
Destinations, like ConnectionFactories, are JMS administered objects that can be stored
and retrieved in JNDI. When configuring a Spring application context you can use the
JNDI factory class JndiObjectFactoryBean / <jee:jndi-lookup> to perform dependency
injection on your object’s references to JMS destinations. However, often this strategy
is cumbersome if there are a large number of destinations in the application or if there
are advanced destination management features unique to the JMS provider. Examples of
such advanced destination management would be the creation of dynamic destinations or
support for a hierarchical namespace of destinations. The JmsTemplate delegates the
resolution of a destination name to a JMS destination object to an implementation of the
interface DestinationResolver . DynamicDestinationResolver is the default
implementation used by JmsTemplate and accommodates resolving dynamic destinations. A
JndiDestinationResolver is also provided that acts as a service locator for
destinations contained in JNDI and optionally falls back to the behavior contained in
DynamicDestinationResolver .
Quite often the destinations used in a JMS application are only known at runtime and
therefore cannot be administratively created when the application is deployed. This is
often because there is shared application logic between interacting system components
that create destinations at runtime according to a well-known naming convention. Even
though the creation of dynamic destinations is not part of the JMS specification, most
vendors have provided this functionality. Dynamic destinations are created with a name
defined by the user which differentiates them from temporary destinations and are often
not registered in JNDI. The API used to create dynamic destinations varies from provider
to provider since the properties associated with the destination are vendor specific.
However, a simple implementation choice that is sometimes made by vendors is to
disregard the warnings in the JMS specification and to use the TopicSession method
createTopic(String topicName) or the QueueSession method createQueue(String
queueName) to create a new destination with default destination properties. Depending
on the vendor implementation, DynamicDestinationResolver may then also create a
physical destination instead of only resolving one.
The boolean property pubSubDomain is used to configure the JmsTemplate with
knowledge of what JMS domain is being used. By default the value of this property is
false, indicating that the point-to-point domain, Queues, will be used. This property
used by JmsTemplate determines the behavior of dynamic destination resolution via
implementations of the DestinationResolver interface.
You can also configure the JmsTemplate with a default destination via the property
defaultDestination . The default destination will be used with send and receive
operations that do not refer to a specific destination.
23.2.4 Message Listener Containers
One of the most common uses of JMS messages in the EJB world is to drive message-driven
beans (MDBs). Spring offers a solution to create message-driven POJOs (MDPs) in a way
that does not tie a user to an EJB container. (See Section 23.4.2, “Asynchronous Reception - Message-Driven POJOs”
for detailed coverage of Spring’s MDP support.)
A message listener container is used to receive messages from a JMS message queue and
drive the MessageListener that is injected into it. The listener container is
responsible for all threading of message reception and dispatches into the listener for
processing. A message listener container is the intermediary between an MDP and a
messaging provider, and takes care of registering to receive messages, participating in
transactions, resource acquisition and release, exception conversion and suchlike. This
allows you as an application developer to write the (possibly complex) business logic
associated with receiving a message (and possibly responding to it), and delegates
boilerplate JMS infrastructure concerns to the framework.
There are two standard JMS message listener containers packaged with Spring, each with
its specialised feature set.
SimpleMessageListenerContainer
This message listener container is the simpler of the two standard flavors. It creates a
fixed number of JMS sessions and consumers at startup, registers the listener using the
standard JMS MessageConsumer.setMessageListener() method, and leaves it up the JMS
provider to perform listener callbacks. This variant does not allow for dynamic adaption
to runtime demands or for participation in externally managed transactions.
Compatibility-wise, it stays very close to the spirit of the standalone JMS
specification - but is generally not compatible with Java EE’s JMS restrictions.
DefaultMessageListenerContainer
This message listener container is the one used in most cases. In contrast to
SimpleMessageListenerContainer , this container variant does allow for dynamic adaption
to runtime demands and is able to participate in externally managed transactions. Each
received message is registered with an XA transaction when configured with a
JtaTransactionManager ; so processing may take advantage of XA transaction semantics.
This listener container strikes a good balance between low requirements on the JMS
provider, advanced functionality such as transaction participation, and compatibility
with Java EE environments.
23.2.5 Transaction management
Spring provides a JmsTransactionManager that manages transactions for a single JMS
ConnectionFactory . This allows JMS applications to leverage the managed transaction
features of Spring as described in Chapter 11, Transaction Management. The JmsTransactionManager performs
local resource transactions, binding a JMS Connection/Session pair from the specified
ConnectionFactory to the thread. JmsTemplate automatically detects such
transactional resources and operates on them accordingly.
In a Java EE environment, the ConnectionFactory will pool Connections and Sessions, so
those resources are efficiently reused across transactions. In a standalone environment,
using Spring’s SingleConnectionFactory will result in a shared JMS Connection , with
each transaction having its own independent Session . Alternatively, consider the use
of a provider-specific pooling adapter such as ActiveMQ’s PooledConnectionFactory
class.
JmsTemplate can also be used with the JtaTransactionManager and an XA-capable JMS
ConnectionFactory for performing distributed transactions. Note that this requires the
use of a JTA transaction manager as well as a properly XA-configured ConnectionFactory!
(Check your Java EE server’s / JMS provider’s documentation.)
Reusing code across a managed and unmanaged transactional environment can be confusing
when using the JMS API to create a Session from a Connection . This is because the
JMS API has only one factory method to create a Session and it requires values for the
transaction and acknowledgement modes. In a managed environment, setting these values is
the responsibility of the environment’s transactional infrastructure, so these values
are ignored by the vendor’s wrapper to the JMS Connection. When using the JmsTemplate
in an unmanaged environment you can specify these values through the use of the
properties sessionTransacted and sessionAcknowledgeMode . When using a
PlatformTransactionManager with JmsTemplate , the template will always be given a
transactional JMS Session .
The JmsTemplate contains many convenience methods to send a message. There are send
methods that specify the destination using a javax.jms.Destination object and those
that specify the destination using a string for use in a JNDI lookup. The send method
that takes no destination argument uses the default destination.
import javax.jms.ConnectionFactory;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.Queue;
import javax.jms.Session;
import org.springframework.jms.core.MessageCreator;
import org.springframework.jms.core.JmsTemplate;
public class JmsQueueSender {
private JmsTemplate jmsTemplate;
private Queue queue;
public void setConnectionFactory(ConnectionFactory cf) {
this.jmsTemplate = new JmsTemplate(cf);
}
public void setQueue(Queue queue) {
this.queue = queue;
}
public void simpleSend() {
this.jmsTemplate.send(this.queue, new MessageCreator() {
public Message createMessage(Session session) throws JMSException {
return session.createTextMessage("hello queue world");
}
});
}
}
This example uses the MessageCreator callback to create a text message from the
supplied Session object. The JmsTemplate is constructed by passing a reference to a
ConnectionFactory . As an alternative, a zero argument constructor and
connectionFactory is provided and can be used for constructing the instance in
JavaBean style (using a BeanFactory or plain Java code). Alternatively, consider
deriving from Spring’s JmsGatewaySupport convenience base class, which provides
pre-built bean properties for JMS configuration.
The method send(String destinationName, MessageCreator creator) lets you send a
message using the string name of the destination. If these names are registered in JNDI,
you should set the destinationResolver property of the template to an instance of
JndiDestinationResolver .
If you created the JmsTemplate and specified a default destination, the
send(MessageCreator c) sends a message to that destination.
23.3.1 Using Message Converters
In order to facilitate the sending of domain model objects, the JmsTemplate has
various send methods that take a Java object as an argument for a message’s data
content. The overloaded methods convertAndSend() and receiveAndConvert() in
JmsTemplate delegate the conversion process to an instance of the MessageConverter
interface. This interface defines a simple contract to convert between Java objects and
JMS messages. The default implementation SimpleMessageConverter supports conversion
between String and TextMessage , byte[] and BytesMesssage , and java.util.Map
and MapMessage . By using the converter, you and your application code can focus on the
business object that is being sent or received via JMS and not be concerned with the
details of how it is represented as a JMS message.
The sandbox currently includes a MapMessageConverter which uses reflection to convert
between a JavaBean and a MapMessage . Other popular implementation choices you might
implement yourself are Converters that use an existing XML marshalling package, such as
JAXB, Castor, XMLBeans, or XStream, to create a TextMessage representing the object.
To accommodate the setting of a message’s properties, headers, and body that can not be
generically encapsulated inside a converter class, the MessagePostProcessor interface
gives you access to the message after it has been converted, but before it is sent. The
example below demonstrates how to modify a message header and a property after a
java.util.Map is converted to a message.
public void sendWithConversion() {
Map map = new HashMap();
map.put("Name", "Mark");
map.put("Age", new Integer(47));
jmsTemplate.convertAndSend("testQueue", map, new MessagePostProcessor() {
public Message postProcessMessage(Message message) throws JMSException {
message.setIntProperty("AccountID", 1234);
message.setJMSCorrelationID("123-00001");
return message;
}
});
}
This results in a message of the form:
MapMessage={
Header={
... standard headers ...
CorrelationID={123-00001}
}
Properties={
AccountID={Integer:1234}
}
Fields={
Name={String:Mark}
Age={Integer:47}
}
}
23.3.2 SessionCallback and ProducerCallback
While the send operations cover many common usage scenarios, there are cases when you
want to perform multiple operations on a JMS Session or MessageProducer . The
SessionCallback and ProducerCallback expose the JMS Session and Session /
MessageProducer pair respectively. The execute() methods on JmsTemplate execute
these callback methods.
23.4.1 Synchronous Reception
While JMS is typically associated with asynchronous processing, it is possible to
consume messages synchronously. The overloaded receive(..) methods provide this
functionality. During a synchronous receive, the calling thread blocks until a message
becomes available. This can be a dangerous operation since the calling thread can
potentially be blocked indefinitely. The property receiveTimeout specifies how long
the receiver should wait before giving up waiting for a message.
23.4.2 Asynchronous Reception - Message-Driven POJOs
In a fashion similar to a Message-Driven Bean (MDB) in the EJB world, the Message-Driven
POJO (MDP) acts as a receiver for JMS messages. The one restriction (but see also below
for the discussion of the MessageListenerAdapter class) on an MDP is that it must
implement the javax.jms.MessageListener interface. Please also be aware that in the
case where your POJO will be receiving messages on multiple threads, it is important to
ensure that your implementation is thread-safe.
Below is a simple implementation of an MDP:
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.TextMessage;
public class ExampleListener implements MessageListener {
public void onMessage(Message message) {
if (message instanceof TextMessage) {
try {
System.out.println(((TextMessage) message).getText());
}
catch (JMSException ex) {
throw new RuntimeException(ex);
}
}
else {
throw new IllegalArgumentException("Message must be of type TextMessage");
}
}
}
Once you’ve implemented your MessageListener , it’s time to create a message listener
container.
Find below an example of how to define and configure one of the message listener
containers that ships with Spring (in this case the DefaultMessageListenerContainer ).
<bean id="messageListener" class="jmsexample.ExampleListener" />
<bean id="jmsContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer">
<property name="connectionFactory" ref="connectionFactory"/>
<property name="destination" ref="destination"/>
<property name="messageListener" ref="messageListener" />
</bean>
Please refer to the Spring javadocs of the various message listener containers for a full
description of the features supported by each implementation.
23.4.3 the SessionAwareMessageListener interface
The SessionAwareMessageListener interface is a Spring-specific interface that provides
a similar contract to the JMS MessageListener interface, but also provides the message
handling method with access to the JMS Session from which the Message was received.
package org.springframework.jms.listener;
public interface SessionAwareMessageListener {
void onMessage(Message message, Session session) throws JMSException;
}
You can choose to have your MDPs implement this interface (in preference to the standard
JMS MessageListener interface) if you want your MDPs to be able to respond to any
received messages (using the Session supplied in the onMessage(Message, Session)
method). All of the message listener container implementations that ship with Spring
have support for MDPs that implement either the MessageListener or
SessionAwareMessageListener interface. Classes that implement the
SessionAwareMessageListener come with the caveat that they are then tied to Spring
through the interface. The choice of whether or not to use it is left entirely up to you
as an application developer or architect.
Please note that the 'onMessage(..)' method of the SessionAwareMessageListener
interface throws JMSException . In contrast to the standard JMS MessageListener
interface, when using the SessionAwareMessageListener interface, it is the
responsibility of the client code to handle any exceptions thrown.
23.4.4 the MessageListenerAdapter
The MessageListenerAdapter class is the final component in Spring’s asynchronous
messaging support: in a nutshell, it allows you to expose almost any class as a MDP
(there are of course some constraints).
Consider the following interface definition. Notice that although the interface extends
neither the MessageListener nor SessionAwareMessageListener interfaces, it can still
be used as a MDP via the use of the MessageListenerAdapter class. Notice also how the
various message handling methods are strongly typed according to the contents of the
various Message types that they can receive and handle.
public interface MessageDelegate {
void handleMessage(String message);
void handleMessage(Map message);
void handleMessage(byte[] message);
void handleMessage(Serializable message);
}
public class DefaultMessageDelegate implements MessageDelegate {
}
In particular, note how the above implementation of the MessageDelegate interface (the
above DefaultMessageDelegate class) has no JMS dependencies at all. It truly is a
POJO that we will make into an MDP via the following configuration.
<bean id="messageListener" class="org.springframework.jms.listener.adapter.MessageListenerAdapter">
<constructor-arg>
<bean class="jmsexample.DefaultMessageDelegate"/>
</constructor-arg>
</bean>
<bean id="jmsContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer">
<property name="connectionFactory" ref="connectionFactory"/>
<property name="destination" ref="destination"/>
<property name="messageListener" ref="messageListener" />
</bean>
Below is an example of another MDP that can only handle the receiving of JMS
TextMessage messages. Notice how the message handling method is actually called
'receive' (the name of the message handling method in a MessageListenerAdapter
defaults to 'handleMessage' ), but it is configurable (as you will see below). Notice
also how the 'receive(..)' method is strongly typed to receive and respond only to JMS
TextMessage messages.
public interface TextMessageDelegate {
void receive(TextMessage message);
}
public class DefaultTextMessageDelegate implements TextMessageDelegate {
}
The configuration of the attendant MessageListenerAdapter would look like this:
<bean id="messageListener" class="org.springframework.jms.listener.adapter.MessageListenerAdapter">
<constructor-arg>
<bean class="jmsexample.DefaultTextMessageDelegate"/>
</constructor-arg>
<property name="defaultListenerMethod" value="receive"/>
<property name="messageConverter">
<null/>
</property>
</bean>
Please note that if the above 'messageListener' receives a JMS Message of a type
other than TextMessage , an IllegalStateException will be thrown (and subsequently
swallowed). Another of the capabilities of the MessageListenerAdapter class is the
ability to automatically send back a response Message if a handler method returns a
non-void value. Consider the interface and class:
public interface ResponsiveTextMessageDelegate {
String receive(TextMessage message);
}
public class DefaultResponsiveTextMessageDelegate implements ResponsiveTextMessageDelegate {
}
If the above DefaultResponsiveTextMessageDelegate is used in conjunction with a
MessageListenerAdapter then any non-null value that is returned from the execution of
the 'receive(..)' method will (in the default configuration) be converted into a
TextMessage . The resulting TextMessage will then be sent to the Destination (if
one exists) defined in the JMS Reply-To property of the original Message , or the
default Destination set on the MessageListenerAdapter (if one has been configured);
if no Destination is found then an InvalidDestinationException will be thrown (and
please note that this exception will not be swallowed and will propagate up the
call stack).
23.4.5 Processing messages within transactions
Invoking a message listener within a transaction only requires reconfiguration of the
listener container.
Local resource transactions can simply be activated through the sessionTransacted flag
on the listener container definition. Each message listener invocation will then operate
within an active JMS transaction, with message reception rolled back in case of listener
execution failure. Sending a response message (via SessionAwareMessageListener ) will
be part of the same local transaction, but any other resource operations (such as
database access) will operate independently. This usually requires duplicate message
detection in the listener implementation, covering the case where database processing
has committed but message processing failed to commit.
<bean id="jmsContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer">
<property name="connectionFactory" ref="connectionFactory"/>
<property name="destination" ref="destination"/>
<property name="messageListener" ref="messageListener"/>
<property name="sessionTransacted" value="true"/>
</bean>
For participating in an externally managed transaction, you will need to configure a
transaction manager and use a listener container which supports externally managed
transactions: typically DefaultMessageListenerContainer .
To configure a message listener container for XA transaction participation, you’ll want
to configure a JtaTransactionManager (which, by default, delegates to the Java EE
server’s transaction subsystem). Note that the underlying JMS ConnectionFactory needs to
be XA-capable and properly registered with your JTA transaction coordinator! (Check your
Java EE server’s configuration of JNDI resources.) This allows message reception as well
as e.g. database access to be part of the same transaction (with unified commit
semantics, at the expense of XA transaction log overhead).
<bean id="transactionManager" class="org.springframework.transaction.jta.JtaTransactionManager"/>
Then you just need to add it to our earlier container configuration. The container will
take care of the rest.
<bean id="jmsContainer" class="org.springframework.jms.listener.DefaultMessageListenerContainer">
<property name="connectionFactory" ref="connectionFactory"/>
<property name="destination" ref="destination"/>
<property name="messageListener" ref="messageListener"/>
<property name="transactionManager" ref="transactionManager"/>
</bean>
23.5 Support for JCA Message Endpoints
Beginning with version 2.5, Spring also provides support for a JCA-based
MessageListener container. The JmsMessageEndpointManager will attempt to
automatically determine the ActivationSpec class name from the provider’s
ResourceAdapter class name. Therefore, it is typically possible to just provide
Spring’s generic JmsActivationSpecConfig as shown in the following example.
<bean class="org.springframework.jms.listener.endpoint.JmsMessageEndpointManager">
<property name="resourceAdapter" ref="resourceAdapter"/>
<property name="activationSpecConfig">
<bean class="org.springframework.jms.listener.endpoint.JmsActivationSpecConfig">
<property name="destinationName" value="myQueue"/>
</bean>
</property>
<property name="messageListener" ref="myMessageListener"/>
</bean>
Alternatively, you may set up a JmsMessageEndpointManager with a given
ActivationSpec object. The ActivationSpec object may also come from a JNDI lookup
(using <jee:jndi-lookup> ).
<bean class="org.springframework.jms.listener.endpoint.JmsMessageEndpointManager">
<property name="resourceAdapter" ref="resourceAdapter"/>
<property name="activationSpec">
<bean class="org.apache.activemq.ra.ActiveMQActivationSpec">
<property name="destination" value="myQueue"/>
<property name="destinationType" value="javax.jms.Queue"/>
</bean>
</property>
<property name="messageListener" ref="myMessageListener"/>
</bean>
Using Spring’s ResourceAdapterFactoryBean , the target ResourceAdapter may be
configured locally as depicted in the following example.
<bean id="resourceAdapter" class="org.springframework.jca.support.ResourceAdapterFactoryBean">
<property name="resourceAdapter">
<bean class="org.apache.activemq.ra.ActiveMQResourceAdapter">
<property name="serverUrl" value="tcp://localhost:61616"/>
</bean>
</property>
<property name="workManager">
<bean class="org.springframework.jca.work.SimpleTaskWorkManager"/>
</property>
</bean>
The specified WorkManager may also point to an environment-specific thread pool -
typically through SimpleTaskWorkManager's "asyncTaskExecutor" property. Consider
defining a shared thread pool for all your ResourceAdapter instances if you happen to
use multiple adapters.
In some environments (e.g. WebLogic 9 or above), the entire ResourceAdapter object may
be obtained from JNDI instead (using <jee:jndi-lookup> ). The Spring-based message
listeners can then interact with the server-hosted ResourceAdapter , also using the
server’s built-in WorkManager .
Please consult the JavaDoc for JmsMessageEndpointManager , JmsActivationSpecConfig ,
and ResourceAdapterFactoryBean for more details.
Spring also provides a generic JCA message endpoint manager which is not tied to JMS:
org.springframework.jca.endpoint.GenericMessageEndpointManager . This component allows
for using any message listener type (e.g. a CCI MessageListener) and any
provider-specific ActivationSpec object. Check out your JCA provider’s documentation to
find out about the actual capabilities of your connector, and consult
GenericMessageEndpointManager 's JavaDoc for the Spring-specific configuration details.
![[Note]](images/note.png) | Note |
---|
JCA-based message endpoint management is very analogous to EJB 2.1 Message-Driven Beans;
it uses the same underlying resource provider contract. Like with EJB 2.1 MDBs, any
message listener interface supported by your JCA provider can be used in the Spring
context as well. Spring nevertheless provides explicit convenience support for JMS,
simply because JMS is the most common endpoint API used with the JCA endpoint management
contract.
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23.6 JMS Namespace Support
Spring 2.5 introduces an XML namespace for simplifying JMS configuration. To use the JMS
namespace elements you will need to reference the JMS schema:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jms="http://www.springframework.org/schema/jms"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/jms http://www.springframework.org/schema/jms/spring-jms.xsd">
</beans>
The namespace consists of two top-level elements: <listener-container/> and
<jca-listener-container/> both of which may contain one or more <listener/> child
elements. Here is an example of a basic configuration for two listeners.
<jms:listener-container>
<jms:listener destination="queue.orders" ref="orderService" method="placeOrder"/>
<jms:listener destination="queue.confirmations" ref="confirmationLogger" method="log"/>
</jms:listener-container>
The example above is equivalent to creating two distinct listener container bean
definitions and two distinct MessageListenerAdapter bean definitions as demonstrated
in Section 23.4.4, “the MessageListenerAdapter”. In addition to the attributes shown
above, the listener element may contain several optional ones. The following table
describes all available attributes:
Table 23.1. Attributes of the JMS <listener> element
Attribute | Description |
---|
id | A bean name for the hosting listener container. If not specified, a bean name will be
automatically generated. | destination (required) | The destination name for this listener, resolved through the DestinationResolver
strategy. | ref (required) | The bean name of the handler object. | method | The name of the handler method to invoke. If the ref points to a MessageListener
or Spring SessionAwareMessageListener , this attribute may be omitted. | response-destination | The name of the default response destination to send response messages to. This will
be applied in case of a request message that does not carry a "JMSReplyTo" field. The
type of this destination will be determined by the listener-container’s
"destination-type" attribute. Note: This only applies to a listener method with a
return value, for which each result object will be converted into a response message. | subscription | The name of the durable subscription, if any. | selector | An optional message selector for this listener. |
The <listener-container/> element also accepts several optional attributes. This
allows for customization of the various strategies (for example, taskExecutor and
destinationResolver ) as well as basic JMS settings and resource references. Using
these attributes, it is possible to define highly-customized listener containers while
still benefiting from the convenience of the namespace.
<jms:listener-container connection-factory="myConnectionFactory"
task-executor="myTaskExecutor"
destination-resolver="myDestinationResolver"
transaction-manager="myTransactionManager"
concurrency="10">
<jms:listener destination="queue.orders" ref="orderService" method="placeOrder"/>
<jms:listener destination="queue.confirmations" ref="confirmationLogger" method="log"/>
</jms:listener-container>
The following table describes all available attributes. Consult the class-level javadocs
of the AbstractMessageListenerContainer and its concrete subclasses for more details
on the individual properties. The javadocs also provide a discussion of transaction
choices and message redelivery scenarios.
Table 23.2. Attributes of the JMS <listener-container> element
Attribute | Description |
---|
container-type | The type of this listener container. Available options are: default , simple ,
default102 , or simple102 (the default value is 'default' ). | container-class | A custom listener container implementation class as fully qualified class name.
Default is Spring’s standard DefaultMessageListenerContainer or
SimpleMessageListenerContainer , according to the "container-type" attribute. | connection-factory | A reference to the JMS ConnectionFactory bean (the default bean name is
'connectionFactory' ). | task-executor | A reference to the Spring TaskExecutor for the JMS listener invokers. | destination-resolver | A reference to the DestinationResolver strategy for resolving JMS Destinations . | message-converter | A reference to the MessageConverter strategy for converting JMS Messages to listener
method arguments. Default is a SimpleMessageConverter . | error-handler | A reference to an ErrorHandler strategy for handling any uncaught Exceptions that
may occur during the execution of the MessageListener . | destination-type | The JMS destination type for this listener: queue , topic or durableTopic . The
default is queue . | client-id | The JMS client id for this listener container. Needs to be specified when using
durable subscriptions. | cache | The cache level for JMS resources: none , connection , session , consumer or
auto . By default ( auto ), the cache level will effectively be "consumer", unless
an external transaction manager has been specified - in which case the effective
default will be none (assuming Java EE-style transaction management where the given
ConnectionFactory is an XA-aware pool). | acknowledge | The native JMS acknowledge mode: auto , client , dups-ok or transacted . A value
of transacted activates a locally transacted Session . As an alternative, specify
the transaction-manager attribute described below. Default is auto . | transaction-manager | A reference to an external PlatformTransactionManager (typically an XA-based
transaction coordinator, e.g. Spring’s JtaTransactionManager ). If not specified,
native acknowledging will be used (see "acknowledge" attribute). | concurrency | The number of concurrent sessions/consumers to start for each listener. Can either be
a simple number indicating the maximum number (e.g. "5") or a range indicating the
lower as well as the upper limit (e.g. "3-5"). Note that a specified minimum is just a
hint and might be ignored at runtime. Default is 1; keep concurrency limited to 1 in
case of a topic listener or if queue ordering is important; consider raising it for
general queues. | prefetch | The maximum number of messages to load into a single session. Note that raising this
number might lead to starvation of concurrent consumers! | receive-timeout | The timeout to use for receive calls (in milliseconds). The default is 1000 ms (1
sec); -1 indicates no timeout at all. | recovery-interval | Specify the interval between recovery attempts, in milliseconds. The default is 5000
ms, that is, 5 seconds. |
phase | The lifecycle phase within which this container should start and stop. The lower the
value the earlier this container will start and the later it will stop. The default is
Integer.MAX_VALUE meaning the container will start as late as possible and stop as
soon as possible. |
Configuring a JCA-based listener container with the "jms" schema support is very similar.
<jms:jca-listener-container resource-adapter="myResourceAdapter"
destination-resolver="myDestinationResolver"
transaction-manager="myTransactionManager"
concurrency="10">
<jms:listener destination="queue.orders" ref="myMessageListener"/>
</jms:jca-listener-container>
The available configuration options for the JCA variant are described in the following
table:
Table 23.3. Attributes of the JMS <jca-listener-container/> element
Attribute | Description |
---|
resource-adapter | A reference to the JCA ResourceAdapter bean (the default bean name is
'resourceAdapter' ). | activation-spec-factory | A reference to the JmsActivationSpecFactory . The default is to autodetect the JMS
provider and its ActivationSpec class (see DefaultJmsActivationSpecFactory ) | destination-resolver | A reference to the DestinationResolver strategy for resolving JMS Destinations . | message-converter | A reference to the MessageConverter strategy for converting JMS Messages to listener
method arguments. Default is a SimpleMessageConverter . | destination-type | The JMS destination type for this listener: queue , topic or durableTopic . The
default is queue . | client-id | The JMS client id for this listener container. Needs to be specified when using
durable subscriptions. | acknowledge | The native JMS acknowledge mode: auto , client , dups-ok or transacted . A value
of transacted activates a locally transacted Session . As an alternative, specify
the transaction-manager attribute described below. Default is auto . | transaction-manager | A reference to a Spring JtaTransactionManager or a
javax.transaction.TransactionManager for kicking off an XA transaction for each
incoming message. If not specified, native acknowledging will be used (see the
"acknowledge" attribute). | concurrency | The number of concurrent sessions/consumers to start for each listener. Can either be
a simple number indicating the maximum number (e.g. "5") or a range indicating the
lower as well as the upper limit (e.g. "3-5"). Note that a specified minimum is just a
hint and will typically be ignored at runtime when using a JCA listener container.
Default is 1. | prefetch | The maximum number of messages to load into a single session. Note that raising this
number might lead to starvation of concurrent consumers! |
|
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