XA Transactions over Camel Routes

Managing multiple transactional resources

Multiple transactional resources

from('jms:inbound?transacted=true').log('Processing message ${body}').policy('DB_PROPAGATION_REQUIRED'). to('sql:insert into audit_log (message) values (:#${body})').end().policy('JMS_PROPAGATION_REQUIRED'). to('jms:outbound').end()

Multiple transactional resources

@Bean DataSource dataSource() { new JdbcDataSource( url: 'jdbc:h2:tcp://localhost/~/test', user: '', password: '' ) }

@Bean ConnectionFactory connectionFactory() { new ActiveMQConnectionFactory( brokerURL: 'tcp://localhost:61616' ) }

Multiple transactional resources

@Bean PlatformTransactionManager dbTransactionManager() { new DataSourceTransactionManager(dataSource: dataSource()) }

@Bean PlatformTransactionManager jmsTransactionManager() { new JmsTransactionManager(connectionFactory: connectionFactory()) }

Multiple transactional resources

@Bean(name = 'DB_PROPAGATION_REQUIRED') SpringTransactionPolicy dbPropagationRequired() { new SpringTransactionPolicy( transactionManager: dbTransactionManager(), propagationBehaviorName: 'PROPAGATION_REQUIRED' ) }

@Bean(name = 'JMS_PROPAGATION_REQUIRED') SpringTransactionPolicy jmsPropagationRequired() { new SpringTransactionPolicy( transactionManager: jmsTransactionManager(), propagationBehaviorName: 'PROPAGATION_REQUIRED' ) }

One single transaction policy

from('jms:inbound?transacted=true').log('Processing message ${body}').transacted('PROPAGATION_REQUIRED').to('sql:insert into audit_log (message) values (:#${body})').to('jms:outbound')

XA transactions & 2PC

* Extracted from DZone’s article “XA Transactions (2PC): A Simple Guide” (see references)

Atomikos transaction manager

* Extracted from “Apache Camel’s Developer Cookbook” (see References)

XA-capable resources

@Bean XADataSource dataSource() { new JdbcDataSource( url: 'jdbc:h2:tcp://localhost/~/test', user: '', password: '' ) }

@Bean XAConnectionFactory connectionFactory() { new ActiveMQXAConnectionFactory( brokerURL: 'tcp://localhost:61616' ) }

Atomikos wrappers@BeanAtomikosDataSourceBean atomikosDataSource() { new AtomikosDataSourceBean( uniqueResourceName: 'xa.h2.oracle', xaDataSource: dataSource() )}

@Bean(destroyMethod = 'close')AtomikosConnectionFactoryBean atomikosConnectionFactory() { def factory = new AtomikosConnectionFactoryBean( uniqueResourceName: 'xa.amq', xaConnectionFactory: connectionFactory(), maxPoolSize: 10, ignoreSessionTransactedFlag: false ) factory.init() factory}

Atomikos wrappers

@BeanUserTransactionImp atomikosUserTransaction() { new UserTransactionImp(transactionTimeout: 300)}

@Bean(initMethod = 'init', destroyMethod = 'close')TransactionManager atomikosTransactionManager() { new UserTransactionManager()}

Single transaction manager & policy

@BeanPlatformTransactionManager xaTransactionManager() { new JtaTransactionManager( transactionManager: atomikosTransactionManager(), userTransaction: atomikosUserTransaction() )}

@Bean(name = 'PROPAGATION_REQUIRED')SpringTransactionPolicy propagationRequired() { new SpringTransactionPolicy( transactionManager: xaTransactionManager(), propagationBehaviorName: 'PROPAGATION_REQUIRED' )}

Error handler route

onException(Throwable).useOriginalMessage().maximumRedeliveries(5).redeliverDelay('5000').to('jms:dlq').log(ERROR, 'Error: \${exception.stacktrace}').end()

Final thoughts

XA is:

- More complex- More expensive- Hard to test- Slower

Use or not?

- Transaction required?- Multiple database updates?- Multiple JMS destinations?- Compensation?

References

- XA transactions & 2PChttp://www.javaworld.com/article/2077714/java-web-development/xa-transactions-using-spring.htmlhttps://dzone.com/articles/xa-transactions-2-phase-commit

- Atomikoshttps://www.atomikos.com/Documentation/GettingStarted

- Camel transaction policieshttp://camel.apache.org/transactional-client.html

- Camel error handlinghttp://camel.apache.org/error-handler.html

- Apache Camel’s Developer Cookbook:https://www.packtpub.com/application-development/apache-camel-developers-cookbook