To enable transactions in a JMS component (thus enabling JMS endpoints to play the role either of a transactional resource or a transactional client), you need to:
set the transacted property
provide the JMS component with a reference to a suitable transaction manager
In addition, you may want to adjust the JMS component's cache level setting. External transaction managers can impact caching performance.
The easiest way to configure a JMS endpoint to participate in transactions is to create a new an instance of a Camel JMS component that has the proper settings. To do so:
Create a
bean
element that has itsclass
attribute set toorg.apache.camel.component.jms.JmsComponent
.This bean creates an instance of the Fuse Mediation Router's JMS component.
Set the bean's
id
attribute to a unique, short, string.The id will be used to create route endpoint's that use this JMS component.
Add an empty
property
child to the bean.Add a
name
attribute with the value ofconfiguration
to theproperty
element.Add a
ref
attribute whose value is the id of aJmsConfiguration
bean to theproperty
element.The
JmsConfiguration
bean is used to configure the JMS component.Create a
bean
element that has itsclass
attribute set toorg.apache.camel.component.jms.JmsConfiguration
.This bean creates an instance of the Fuse Mediation Router's JMS component configuration.
Set the bean's
id
attribute to the value supplied for theref
attribute in Step 5.Add a
property
child to the bean to configure the JMS connection factory.Set the
name
attribute toconnectionFactory
.Set the
ref
attribute to the id of a bean that configures a JMS connection factory.
Add an empty
property
child to the bean that specifies the transaction manager the component will use.Set the
name
attribute totransactionManager
.Set the
ref
attribute to the id of a bean that configures transaction manager the endpoint will use.
Add an empty
property
child to the bean that configures the component to participate in transactions.Set the
name
attribute totransacted
.Set the
value
attribute totrue
.The transacted property determines if the endpoint can participate in transactions.
Optionally add an empty
property
child to the bean to change the default cache level.Set the
name
attribute tocacheLevelName
.Set the
value
attribute to to a valid cache level.
The JmsComponent
bean's id
specifies
the URI prefix used by JMS endpoints that will use the transactional JMS
component. For example, in Example 3.1 the
JmsComponent
bean's id
equals
jmstx
, so endpoint that use the configured JMS component use the
jmstx:
prefix.
The JmsConfiguration
class supports a large number of other properties,
which are essentially identical to the JMS URI options described in
JMS in EIP Component Reference.
The settings for JMS cache level can impact performance when you are using transactions.
The default cache level is CACHE_AUTO
. This default auto detects if an external
transaction manager is in use and sets the cache level as follows:
CACHE_CONSUMER
if only local JMS resources are in useCACHE_NONE
if an external transaction manager is in use
This behavior guarantees that there will not be any conflicts between caching and the transaction manager because some XA transaction managers require that caching is disabled. However, this behavior may not produce optimal performance.
If your transaction manager does not require that caching be disabled, you can raise the cache level to improve performance. Consult your transaction manager's documentation to determine what caching level it can support. Then override the default cache level by setting the JMS component's cacheLevelName property to the new cache level.
See JMS in EIP Component Reference for information on setting the cache level of the JMS component.
Example 3.1 shows the configuration of a JMS
component, jmstx
that supports Spring transactions. The JMS component is
layered over an embedded instance of Apache ActiveMQ and the transaction manager is an
instance of JmsTransactionManager
.
Example 3.1. JMS Transaction Manager Configuration
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://camel.apache.org/schema/spring http://camel.apache.org/schema/spring/camel-spring.xsd"> ... <bean id="jmstx" class="org.apache.camel.component.jms.JmsComponent"> <property name="configuration" ref="jmsConfig" /> </bean> <bean id="jmsConfig" class="org.apache.camel.component.jms.JmsConfiguration"> <property name="connectionFactory" ref="jmsConnectionFactory"/> <property name="transactionManager" ref="jmsTransactionManager"/> <property name="transacted" value="true"/> <property name="cacheLevelName" value="CACHE_CONNECTION"/> </bean> <bean id="jmsTransactionManager" class="org.springframework.jms.connection.JmsTransactionManager"> <property name="connectionFactory" ref="jmsConnectionFactory" /> </bean> <bean id="jmsConnectionFactory" class="org.apache.activemq.ActiveMQConnectionFactory"> <property name="brokerURL" value="vm://broker1?brokerConfig=xbean:tutorial/activemq.xml"/> </bean> </beans>
To use this JMS component in a route you would use the URI prefix jmstx:
as
shown in Example 3.2.
Example 3.2. URI for Using Transacted JMS Endpoint
from("jmstx:queue:rawStockQuotes") .process(myFormatter) .to("jmstx:queue:formattedStockQuotes");