Testing JTA XA distributed transaction with JPA / Hibernate / MySQL

https://stackoverflow.com/questions/14727570

07-03-2022
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Question

My goal is to have a standalone solution for building JUnit tests for local and distributed transactions using JPA over Hibernate over MySQL.

So far, I have been able to use an XADataSource to access a XAResource and manage the distributed transaction following the 2 phase commit protocol. However, I have to issue SQL statements directly.

I have been trying to do the same but using JPA 2.0 persistence. I'm using simple-jndi to have an in-memory JNDI implementation.

However I keep getting NullPointerException whenever Hibernate tries to access the TransactionManager.

Any ideas? What is missing from my configuration?

Here's what I would like to do:

    // Create the XA datasource instance directly
    MysqlXADataSource mysqlDS = new MysqlXADataSource();
    mysqlDS.setServerName("localhost");
    mysqlDS.setDatabaseName("test");
    mysqlDS.setUser("root");
    mysqlDS.setPassword("rootroot");

    // setup local JNDI
    final XADataSource xaDataSource = (XADataSource) mysqlDS;

    InitialContext ctx = new InitialContext(  );
    ctx.bind("java:/ExampleDS", xaDataSource);

    {
        System.out.println("Lookup...");
        Object o = ctx.lookup("java:/ExampleDS");
        System.out.println("Test lookup: " + o);
    }

    // XID - transaction ID

    // global transaction identifier
    // -      --          --
    byte[] gtrid = new byte[] { 0x44, 0x11, 0x55, 0x66 };

    // branch qualifier
    // -      ----
    byte[] bqual = new byte[] { 0x00, 0x22, 0x00 };

    // combination of gtrid and bqual must be unique

    Xid xid1 = new com.mysql.jdbc.jdbc2.optional.MysqlXid(gtrid, bqual, 0);
        // byte[] gtrid, byte[] bqual, int formatId


    // before transaction
    {
        XADataSource xaDS = (XADataSource) ctx.lookup("java:/ExampleDS");

        XAConnection xaconn = xaDS.getXAConnection();
        Connection conn = xaconn.getConnection();
        XAResource xares = xaconn.getXAResource();

        /* the transaction begins */
        System.out.println("Start transaction");
        xares.start(xid1, TMNOFLAGS);
    }


    // JPA code

    EntityManagerFactory emf;
    emf = Persistence.createEntityManagerFactory("MyPersistenceUnit"); // defined in persistence.xml
    EntityManager em = emf.createEntityManager();

    // System.out.println("begin");
    // em.getTransaction().begin();

    System.out.println("new ContactBook");
    ContactBook contactBook = new ContactBook("Alice");

    System.out.println("addContacts");
    contactBook.addContact("Alice", 100100100);
    contactBook.addContact("Bob", 200200200);
    contactBook.addContact("Charlie", 300300300);

    System.out.println("persist");
    em.persist(contactBook);
    //em.flush();

    // System.out.println("commit");
    // em.getTransaction().commit();


    // after transaction
    {
        XADataSource xaDS = (XADataSource) ctx.lookup("java:/ExampleDS");
        System.out.println("xaDS " + xaDS);

        XAConnection xaconn = xaDS.getXAConnection();
        Connection conn = xaconn.getConnection();
        XAResource xares = xaconn.getXAResource();

        System.out.println("End transaction");
        xares.end(xid1, TMSUCCESS);

        // prepare, commit

        System.out.print("Prepare... ");
        int rc1 = xares.prepare(xid1);
        System.out.println(xaString(rc1));

        if (rc1 == XA_OK) {
            System.out.println("Commit");
            xares.commit(xid1, /*onePhase*/ false);
        } else if(rc1 == XA_RDONLY) {
            System.out.println("Commit no necessary - operations were read only");
        } else {
            throw new IllegalStateException("Unexpected case!");
        }
    }

Here is persistence.xml:

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
version="2.0">
<persistence-unit name="ContactBookPersistenceUnit" transaction-type="JTA">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    <jta-data-source>java:/ExampleDS</jta-data-source>
    <properties>
        <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
        <property name="hibernate.hbm2ddl.auto" value="create" />
        <property name="hibernate.show_sql" value="true" />

        <property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup"/>

        <property name="current_session_context_class" value="jta"/>
        <!-- <property name="hibernate.session_factory_name" value="java:/hibernate/MySessionFactory"/> optional -->

        <property name="hibernate.transaction.factory_class" value="org.hibernate.transaction.JTATransactionFactory"/>
        <property name="hibernate.connection.release_mode" value="auto"/>
        <!-- setting above is important using XA-DataSource on SQLServer,
            otherwise SQLServerException: The function START: has failed. No transaction cookie was returned.-->

        <!--property name="hibernate.cache.use_second_level_cache" value="true"/-->
        <!--property name="hibernate.cache.use_query_cache" value="true"/-->

        <!-- property name="hibernate.cache.region.factory_class"   value="org.hibernate.cache.infinispan.InfinispanRegionFactory"/-->
    </properties>
</persistence-unit>

Solution

I believe you cannot use JTA transactions when you are outside a Java EE container (or at least there is no easy way to do this).

Use RESOURCE-LOCAL

There is nothing that requires JTA in your example: you are just looking up a data source in a Java SE environment. I think declaring your XA data source as resource-local would solve your problem. Put this in your persistence.xml:

<persistence-unit name="ContactBookPersistenceUnit" transaction-type="RESOURCE-LOCAL">
    [...]
    <non-jta-data-source>java:/ExampleDS</jta-data-source>

I have not tested this code directly, but I have used a similar approach in web applications written for the Apache Tomcat server.