Spring的具有不同transactionManagers的嵌套事务

Question

I'm new to Spring's transaction management having troubles to tackle the following scenario of nested transactions while integrating Spring (3.2) and Hibernate (3.6).

I've declared two appContext files as following.

File1) applicationContext-student.xml

    <bean id="studentProjSessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> 
        ...**dataSource1_on_Machine1**...
    </bean>
    <bean id="studentProjTransactionManager"
            class="org.springframework.orm.hibernate3.HibernateTransactionManager">
            <property name="sessionFactory" ref="studentProjSessionFactory" />
    </bean>
    <tx:annotation-driven transaction-manager="studentProjTransactionManager" />

    <bean id="studentDao" class="com.my.univ.employee.dao.studentHibDao" scope="singleton" />

    <bean id="studentService" class="com.my.univ.student.service.studentServiceImpl" scope="singleton">
            <property name="studentDao" ref="studentDao" />
    </bean>

File2) applicationContext-employee.xml

<bean id="employeeProjSessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean"> 
            ........**dataSource2_on_Machine2**...
</bean>
<bean id="employeeProjTransactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory" ref="employeeProjSessionFactory" />
</bean>
<tx:annotation-driven transaction-manager="employeeProjTransactionManager" />

<bean id="employeeDao" class="com.my.univ.employee.dao.EmployeeHibDao" scope="singleton" />

<bean id="employeeService" class="com.my.univ.employee.service.EmployeeServiceImpl" scope="singleton">
        <property name="employeeDao" ref="employeeDao" />
</bean>

Imported above two files in the following file.

File3) applicationContext-university.xml

<import resource="applicationContext-student.xml" />
<import resource="applicationContext-employee.xml" />

<bean id="personService" class="com.my.univ.person.service.PersonServiceImpl" scope="singleton">
        <property name="studentService" ref="studentService" />
        <property name="employeeService" ref="employeeService" />
</bean>

Questions

Let's assume that method level @Transactional annotations are provided with the right txManager names in studentService and employeeService but not in personService.

Q1) If I declare a method in personService as @Transactional, which txManager gets picked?

Q2) How does the nested txManager scenario work if the txManagers in the hierarchy are different from each other?

Ex: If a @Transactional method in personService invokes a @Transactional method in studentService and then another @Transactional method in employeeService (with in the same method of personService).

Q3) How does the commit, rollback elements work in above scenario.

Q4) Readonly operations vs Read/Write operations in above scenario.

It'd be great if anybody could clarify the above.

Thanks.

Answer 1

The @Transactional annotation takes as a value the bean name of the transaction manager. From the documentation :

public abstract String value
A qualifier value for the specified transaction.
May be used to determine the target transaction manager, matching the qualifier value (or the bean name) of a specific PlatformTransactionManager bean definition.

Default:
""

So in your case, explicitly defining:

@Transactional("studentProjTransactionManager")
@Transactional("employeeProjTransactionManager")

should wrap transactionally using the right transaction manager.