Can only perform operation while a transaction is active - jpa

Question

I am using OpenJPA in cxf(jax-rs) + Struts 2. No external transaction manager. Why am I getting "Can only perform operation while a transaction is active."?
My persistence.xml is like this:
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="myPU"
transaction-type="RESOURCE_LOCAL">
<class>com.bb.bba.entity.Advertisement</class>
<class>com.bb.bba.entity.Poi</class>
<properties>
<property name="openjpa.ConnectionDriverName" value="org.apache.derby.jdbc.ClientDriver" />
<property name="openjpa.ConnectionURL" value="jdbc:derby://localhost:1527/bba;create=true" />
<property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema" />
<property name="openjpa.DynamicEnhancementAgent" value="false" />
<property name="openjpa.RuntimeUnenhancedClasses" value="supported" />
<property name="openjpa.ConnectionUserName" value="APP" />
<property name="openjpa.ConnectionPassword" value="asdasd" />
<property name="openjpa.Log" value="SQL=TRACE"/>
</properties>
</persistence-unit>
</persistence>
I am getting the following error.
35692 2012-06-02 03:50:57,847 DEBUG [http-33791-1] resolver.DefaultTraversableResolver.initJpa (DefaultTraversableResolver.java:77) - Found javax.persistence.PersistenceUtil on classpath.
35729 2012-06-02 03:50:57,884 DEBUG [http-33791-1] resolver.DefaultTraversableResolver.initJpa (DefaultTraversableResolver.java:91) - Instantiated an instance of org.apache.bval.jsr303.resolver.JPATraversableResolver.
35755 2012-06-02 03:50:57,910 TRACE [http-33791-1] jsr303.DefaultMessageInterpolator.loadBundle (DefaultMessageInterpolator.java:189) - ValidationMessages not found by thread local classloader
35755 2012-06-02 03:50:57,910 TRACE [http-33791-1] jsr303.DefaultMessageInterpolator.loadBundle (DefaultMessageInterpolator.java:189) - ValidationMessages not found by validator classloader
35756 2012-06-02 03:50:57,911 DEBUG [http-33791-1] jsr303.DefaultMessageInterpolator.getFileBasedResourceBundle (DefaultMessageInterpolator.java:176) - ValidationMessages not found. Delegating to org.apache.bval.jsr303.ValidationMessages
35778 2012-06-02 03:50:57,933 DEBUG [http-33791-1] xml.ValidationParser.parseXmlConfig (ValidationParser.java:88) - No META-INF/validation.xml found. Using annotation based configuration only.
646 myPU INFO [http-33791-1] openjpa.Runtime - OpenJPA dynamically loaded a validation provider.
922 myPU INFO [http-33791-1] openjpa.Runtime - Starting OpenJPA 2.1.1
1703 myPU INFO [http-33791-1] openjpa.jdbc.JDBC - Using dictionary class "org.apache.openjpa.jdbc.sql.DerbyDictionary".
11326 myPU WARN [http-33791-1] openjpa.Enhance - Creating subclass for "[class com.bb.bba.entity.Poi, class com.bb.bba.entity.Advertisement]". This means that your application will be less efficient and will consume more memory than it would if you ran the OpenJPA enhancer. Additionally, lazy loading will not be available for one-to-one and many-to-one persistent attributes in types using field access; they will be loaded eagerly instead.
Here I am
...... nonfatal user error>
org.apache.openjpa.persistence.TransactionRequiredException: Can only
perform operation while a transaction is active.
at org.apache.openjpa.kernel.BrokerImpl.assertActiveTransaction(BrokerImpl.java:4658)
at org.apache.openjpa.kernel.DelegatingBroker.assertActiveTransaction(DelegatingBroker.java:1386)
at org.apache.openjpa.persistence.EntityManagerImpl.flush(EntityManagerImpl.java:661)
at com.bb.bba.dao.MyDao.createPoi(MyDao.java:21)
at com.bb.bba.services.Service.createPoi(POIService.java:36)

Answer 1

You will have to open a transaction before you can perform operations on the EntityManager. That's expected behavior. You will have find some transaction strategy for your application. So you have to decide which component opens transactions (especially on which layer) and how it is done (declarative or programmatic).
What other frameworks are you using? If you are for example also using Spring, you can very easily manage transactions using Spring's declarative transaction management support.
http://static.springsource.org/spring/docs/3.1.x/spring-framework-reference/html/transaction.html

Answer 2

The problem is solved. I was using resource_local which means I am responsible for the transaction. Adding em.getTransaction.begin solved the issue.