Spring & Hibernate: non transactional service methods

Question

I want my read methods not to use a transaction since this is just not needed at all, I only mark my create/update methods with @Transactional. But how do I do this? I have a pretty basic configuration of Spring with etc...

SessionFactory is injected in my DAO, and in each method I call sessionFactory. getCurrentSession().doQueryStuff();

This, however results in this error:

org.hibernate.HibernateException: No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here

If you need my Spring configuration:

<?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:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:oxm="http://www.springframework.org/schema/oxm"
xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd
    http://www.springframework.org/schema/oxm
    http://www.springframework.org/schema/oxm/spring-oxm-3.0.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
    http://www.springframework.org/schema/util
    http://www.springframework.org/schema/util/spring-util-3.0.xsd">

<context:annotation-config />
<context:component-scan base-package="be.howest.kidscalcula" />
<mvc:annotation-driven />

<bean id="viewResolver"
    class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="prefix">
        <value>/WEB-INF/views/</value>
    </property>
    <property name="suffix">
        <value>.jsp</value>
    </property>
</bean>


<bean id="myDataSource"
    class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="com.mysql.jdbc.Driver" />
    <property name="url" value="jdbc:mysql://localhost/kidscalcula" />
    <property name="username" value="root" />
    <property name="password" value="" />
</bean>

<bean class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"
    id="sessionFactory">
    <property name="dataSource" ref="myDataSource" />
    <property name="mappingResources">
        <list>
            <value>be/howest/kidscalcula/model/Foto.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Kindleerplanonderdeel.hbm.xml
            </value>
            <value>be/howest/kidscalcula/model/Klas.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Leerkracht.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Leerling.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Leerplan.hbm.xml</value>
            <value>be/howest/kidscalcula/model/LeerplanOefenreeks.hbm.xml
            </value>
            <value>be/howest/kidscalcula/model/Leerplanonderdeel.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Niveau.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Oefenreeks.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Overgangsregel.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Rapport.hbm.xml</value>
            <value>be/howest/kidscalcula/model/RapportLeerplanonderdeel.hbm.xml
            </value>
            <value>be/howest/kidscalcula/model/Schooljaar.hbm.xml</value>
            <value>be/howest/kidscalcula/model/Subonderdeel.hbm.xml</value>
        </list>
    </property>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
            <prop key="hibernate.connection.pool_size">3</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.format_sql">true</prop>
            <prop key="hibernate.use_sql_comments">true</prop>
            <prop key="hibernate.cache.use_second_level_cache">false</prop>

        </props>
    </property>
</bean>

<!-- Configure the multipart resolver -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- one of the properties available; the maximum file size in bytes -->
    <property name="maxUploadSize" value="500000" />
</bean>


<!--
    Transaction manager for a single Hibernate SessionFactory (alternative
    to JTA)
-->
<bean id="transactionManager"
    class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory">
        <ref bean="sessionFactory" />
    </property>
</bean>

<tx:annotation-driven />

Does this error have anything to do with the fact that Propagation is standard Required?

Answer 1

Mark the method as transactional and read only to ensure the transaction does not modify any data:

@Transactional(readOnly=true)

This is an useful optimization when working with Hibernate. To read more on the implications of this annotation, here is a great post: Read-Only transactions with Spring and Hibernate

Answer 2

As the message clearly says, no session is bound to the thread and the configuration you have specified does NOT allow a "non-transaction" session to be created. I will try to explain each these of scenarios.

When Spring's transaction is enabled in your configuration(as you have done), Spring will wrap the SessionFactory object with a proxy that prevents creation of new sessions, if not already present, when SessionFactory.getCurrentSession is called. The proxy will only get the current session that is bound to the thread local and no ad-hoc session(non-transactional) creation is allowed by your code. This is how your configuration is preventing non-trasactional session creation.

When you annotate a method/class with @Transactional, Spring's TransactionInterceptor will create a session and bind it to the current thread when the method is called so that it is available later. Spring's OpenSessionInViewFilter, if enabled, will also bind a session to the current thread. Since you aren't doing any of these, no thread bound session is found.

What you should do is annotate your class with @Transactional(readOnly = True) and then annotate your create/update/delete methods with @Transactional(readOnly = False). It is important that you have a read-only transaction when you are reading data. This assures you that nobody can commit data during that call.

Answer 3

It is possible to start a session outside of a transaction even when using Spring transaction management. Call sessionFactory.openSession() to get hold of a new session. This session is local in that it is not bound to a thread and so won't be returned when you call sessionFactory.getCurrentSession() . You'll have to manage it and make sure it's properly closed at the the end of your session or if an error occurs.

Answer 4

You can not access the data without an (hibernate) session.

One way to provide such a session is a (when using spring):

• org.springframework.orm.hibernate3.support.OpenSessionInViewFilter or
• org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter (this depends on the way you use your persistence provider)

The positive side effect of this fiters is, that the session is still open when the JSP Views are rendered - so you will have no lazy loading problems when accessing such a not yet loaded property while rendering.

@see http://community.jboss.org/wiki/OpenSessioninView