Templth's blog: Tranql and XAPool

Geronimo uses an interesting project to transform a jdbc driver into a resource adapter. This project is called Tranql. Its home page is http://tranql.codehaus.org/.

This page doesn't show a lot of informations and it is preferable to go to look at directly in the cvs ;-). The cvs is hosted by codehaus (cvs.tranql.codehaus.org) and the cvs root is /home/projects/tranql/scm.

The project only wrap JDBC driver and doesn't add support to convert a no-xa driver into an xa driver... An interested approach is to develop an integration between Tranql and XAPool. So you can easily create an XA DataSource from a simple DataSource and manage its connections with a JCA connection manager.

For example, with Tranql, you can configure a pool of connections with JCA in this way (using the Spring JCA support of Spring):


<bean id="tranqlManagedConnectionFactory"
      class="org.tranql.connector.jdbc.XADriverMCF">
  <property name="driverName">
    <value>org.hsqldb.jdbcDriver</value>
  </property>
  <property name="url">
    <value>jdbc:hsqldb:hsql://localhost:9002</value>
  </property>
  <property name="user">
    <value>sa</value>
  </property>
  <property name="password">
    <value></value>
  </property>
</bean>

So, to transform this DataSource in a XA compliant one, you only need to change the implementation of the ManagedConnectionManager. This XAPoolDataSourceMCF one integrates XAPool and use its StandardXADataSource class.
The configuration is now:


<bean id="tranqlManagedConnectionFactory"
      class="org.tranql.connector.jdbc.XAPoolDataSourceMCF ">
  <property name="driverName">
    <value>org.hsqldb.jdbcDriver</value>
  </property>
  <property name="url">
    <value>jdbc:hsqldb:hsql://localhost:9002</value>
  </property>
  <property name="user">
    <value>sa</value>
  </property>
  <property name="password">
    <value></value>
  </property>
</bean>

Note: A big problem is that XAPool internally manages the enlistment/delistment of XAResource. So you need to patch this tool to remove the call of enlist and delist on the current transaction.

Here is a sample implementation of XAPoolDataSourceMCF:


package org.tranql.connector.jdbc;

import java.sql.SQLException;

import javax.sql.XAConnection;
import javax.sql.XADataSource;

import org.enhydra.jdbc.standard.StandardXADataSource;
import org.tranql.connector.AllExceptionsAreFatalSorter;

public class XAPoolDataSourceMCF extends AbstractXADataSourceMCF {

  public XAPoolDataSourceMCF() {
    super(new StandardXADataSource(),new AllExceptionsAreFatalSorter());
  }

  public String getUserName() {
    return ((StandardXADataSource)xaDataSource).getUser();
  }

  public String getPassword() {
    return ((StandardXADataSource)xaDataSource).getPassword();
  }

  public void setDriverName(String driverName) {
    try {
      ((StandardXADataSource)xaDataSource).setDriverName(driverName);
    } catch (SQLException ex) { ex.printStackTrace(); }
  }

  public void setUrl(String url) {
    ((StandardXADataSource)xaDataSource).setUrl(url);
  }

  public void setUser(String user) {
    ((StandardXADataSource)xaDataSource).setUser(user);
  }

  public void setPassword(String password) {
    ((StandardXADataSource)xaDataSource).setPassword(password);
  }

}