1358-advising-transactional-operations.md

13.5.8Advising transactional operations

Suppose you want to execute_both_transactional_and_some basic profiling advice. How do you effect this in the context of``?

When you invoke theupdateFoo(Foo)method, you want to see the following actions:

• Configured profiling aspect starts up.

• Transactional advice executes.

• Method on the advised object executes.

• Transaction commits.

• Profiling aspect reports exact duration of the whole transactional method invocation.

This chapter is not concerned with explaining AOP in any great detail (except as it applies to transactions). SeeChapter7,Aspect Oriented Programming with Springfor detailed coverage of the following AOP configuration and AOP in general.

Here is the code for a simple profiling aspect discussed above. The ordering of advice is controlled through theOrderedinterface. For full details on advice ordering, seethe section called “Advice ordering”. .

package x.y;

import org.aspectj.lang.ProceedingJoinPoint;
import org.springframework.util.StopWatch;
import org.springframework.core.Ordered;

public class SimpleProfiler implements Ordered {

	private int order;

	// allows us to control the ordering of advice
	public int getOrder() {
		return this.order;
	}

	public void setOrder(int order) {
		this.order = order;
	}

	// this method is the around advice
	public Object profile(ProceedingJoinPoint call) throws Throwable {
		Object returnValue;
		StopWatch clock = new StopWatch(getClass().getName());
		try {
			clock.start(call.toShortString());
			returnValue = call.proceed();
		} finally {
			clock.stop();
			System.out.println(clock.prettyPrint());
		}
		return returnValue;
	}
}

<?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:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/tx
		http://www.springframework.org/schema/tx/spring-tx.xsd
		http://www.springframework.org/schema/aop
		http://www.springframework.org/schema/aop/spring-aop.xsd">

	<bean id="fooService" class="x.y.service.DefaultFooService"/>

	<!-- this is the aspect -->
	<bean id="profiler" class="x.y.SimpleProfiler">
		<!-- execute before the transactional advice (hence the lower order number) -->
		<property name="order" __value="1"__/>
	</bean>

	<tx:annotation-driven transaction-manager="txManager" __order="200"__/>

	<aop:config>
			<!-- this advice will execute around the transactional advice -->
			<aop:aspect id="profilingAspect" ref="profiler">
				<aop:pointcut id="serviceMethodWithReturnValue"
						expression="execution(!void x.y..*Service.*(..))"/>
				<aop:around method="profile" pointcut-ref="serviceMethodWithReturnValue"/>
			</aop:aspect>
	</aop:config>

	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
		<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"/>
		<property name="url" value="jdbc:oracle:thin:@rj-t42:1521:elvis"/>
		<property name="username" value="scott"/>
		<property name="password" value="tiger"/>
	</bean>

	<bean id="txManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource"/>
	</bean>

</beans>

The result of the above configuration is afooServicebean that has profiling and transactional aspects applied to it_in the desired order_. You configure any number of additional aspects in similar fashion.

The following example effects the same setup as above, but uses the purely XML declarative approach.

<?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:aop="http://www.springframework.org/schema/aop"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans
		http://www.springframework.org/schema/beans/spring-beans.xsd
		http://www.springframework.org/schema/tx
		http://www.springframework.org/schema/tx/spring-tx.xsd
		http://www.springframework.org/schema/aop
		http://www.springframework.org/schema/aop/spring-aop.xsd">

	<bean id="fooService" class="x.y.service.DefaultFooService"/>

	<!-- the profiling advice -->
	<bean id="profiler" class="x.y.SimpleProfiler">
		<!-- execute before the transactional advice (hence the lower order number) -->
		__<property name="order" value="1__"/>
	</bean>

	<aop:config>
		<aop:pointcut id="entryPointMethod" expression="execution(* x.y..*Service.*(..))"/>
		<!-- will execute after the profiling advice (c.f. the order attribute) -->

		<aop:advisor advice-ref="txAdvice" pointcut-ref="entryPointMethod" __order="2__"/>
		<!-- order value is higher than the profiling aspect -->

		<aop:aspect id="profilingAspect" ref="profiler">
			<aop:pointcut id="serviceMethodWithReturnValue"
					expression="execution(!void x.y..*Service.*(..))"/>
			<aop:around method="profile" pointcut-ref="serviceMethodWithReturnValue"/>
		</aop:aspect>

	</aop:config>

	<tx:advice id="txAdvice" transaction-manager="txManager">
		<tx:attributes>
			<tx:method name="get*" read-only="true"/>
			<tx:method name="*"/>
		</tx:attributes>
	</tx:advice>

	<!-- other <bean/> definitions such as a DataSource and a PlatformTransactionManager here -->

</beans>

The result of the above configuration will be afooServicebean that has profiling and transactional aspects applied to it_in that order_. If you want the profiling advice to execute_after_the transactional advice on the way in, and_before_the transactional advice on the way out, then you simply swap the value of the profiling aspect bean’sorderproperty so that it is higher than the transactional advice’s order value.

You configure additional aspects in similar fashion.