JDBC, JMS and EJB transactions - possible problem?

Question

Hello,
          I am using Oracle 9, Weblogic 8.1 SP 4, MyEclipse and
          XDoclet.
          In my current project I have the following piece of code
          in one of my message driven beans (code cited as pseudocode
          without unnecessary details):
          * @ejb.bean name="MyMessageProcessor"
          * display-name="Display name for a MyMessageProcessor"
          * jndi-name="ejb/MyMessageProcessor"
          * description="Bean MyMessageProcessor"
          * destination-type="javax.jms.Queue"
          * transaction-type="Container"
          * acknowledge-mode="Auto-acknowledge"
          * subscription-durability="Durable"
          * generate="false"
          * @ejb.transaction type="Required"
          public class MyMessageProcessor implements MessageDrivenBean, MessageListener {
          public void onMessage(Message msg) {
               try {
                    //obtaining connections to two different databases via JNDi
                    java.sql.Connection connOne =
                    ((DataSource)ctx.lookup("DataSourceOne")).getConnection();          
                    java.sql.Connection connTwo =
                         ((DataSource)ctx.lookup("DataSourceTwo")).getConnection();
                    // performing some UPDATEs and INSERTs on connOne and connTwo
                    // calling some other methods of this bean
                    //creating the reply JMS message and sending it to another JMS queue
                    Message msgTwo = this.createReplyMessage(msg)
                    this.queueSender.send(msgTwo);
                    //commiting everything
                    this.queueSession.commit();          
               } catch (Exception ex) {
               try {
                    if (this.queueSession!=null) this.queueSession.rollback();
               } catch (JMSException JMSEx) {};     
               this.context.setRollbackOnly();
          Some days ago (before the final remarks from my client) there used to be only one DataSource configurated on the basis of the
          connection pool with non-XA jdbc driver. Everything worked fine
          including the transactions (if anything wrong happend not only wasn't the replymessage sent, but also no changes were written
          to database and the incomming message was thrown back to the my bean's
          queue).
          When I deployed the second DataSource I was informed by an error message, that only one non-transactional resource may
          participate in a global transaction. When I changed both datasources
          to depend on underlying datasources with transatcional (XA) jdbc drivers, everything stopped working. Even if
          EJB transaction was theoretically successfully rolledbacked, the changed were written to the database
          and the JMS message wasn't resent to the JMS queue.
          So here are my questions:
               1. How to configure connection pools to work in such situations? What JDBC drivers should I choose?
               Are there any global server configurations, which may influence this situation?
               2. Which jdbc drivers should I choose so that the container was able to rollback the database transactions
               (of course, if necessary)?
               3. Are there any JMS Queue settings, which would disable the container to send message back to the
               queue in case of setRollbackOnly()? How should be the Queue configurated?
          As I am new to the topic and the deadline for the project seems to be too close I would be grateful
          for any help.
          This message was sent to EJB list and JDBC list.
          Sincerely yours,
          Marcin Zakidalski

Answer 1

Hi,
          I found these information extremely useful and helpful.
          The seperate transaction for sending messages was, of course, unintentional. Thanks a lot.
          Anyway, I still have some problems. I have made some changes to the
          code cited in my previous mail. These changes included changing QueueSessions
          to non-transactional. I also set the "Honorate global transactions" to true.
          I am using XA JDBC driver. After setting "Enable local transactions" to false
          (I did it, because I assume that JDBC transactions should be part on the global
          EJB transaction) I got the following error:
          java.sql.SQLException: SQL operations are not allowed with no global transaction by default for XA drivers. If the XA
          driver supports performing SQL operations with no global transaction, explicitly allow it by setting
          "SupportsLocalTransaction" JDBC connection pool property to true. In this case, also remember to complete the local
          transaction before using the connection again for global transaction, else a XAER_OUTSIDE XAException may result. To
          complete a local transaction, you can either set auto commit to true or call Connection.commit() or Connection.rollback().
          I have also inspected the calls of methods of bean inside of onMessage() method just to check, whether
          the transactions are correctly initialized (using the weblogic.transaction.Transaction class).
          My questions are as follows:
          1. Any suggestions how to solve it? I have gone through the google answers on that problem and only
          thing I managed to realize that JDBC must start its own transaction. Is there any way to prohibit it
          from doing that? Can using setAutocommit(true/false) change the situation for better?
          2. How to encourage the JDBC driver to be a part of EJB transaction?
          3. As I have noticed each of ejb method has its own transactions (transactions have different
          Xid). Each method of the bean has "required" transaction attribute. Shouldn't it work in such
          way that if already started transaction exists it is used by the called method?
          4. The DataSources are obtained in my application via JNDI and in the destination environment I will have slight
          impact on the configuration of WebLogic. What is least problematic and most common WebLogic configuration which would
          enable JDBC driver to participate in the EJB transaction? Is it the WebLogic configuration problem or can it be
          solved programmically?
          Currently my module works quite fine when "enable local transactions" for DataSources is set to true, but this way
          I am loosing the ability to perform all actions in one transaction.
          Any suggestions / hints are more than welcomed. This message was posted to jdbc list and ejb list.
          Marcin