It seems quite hard to configure a JNDI Resource in Tomcat. Especially when it comes to configuring XA capable resources. The key lies in understanding how Resources work/need to be configured. A Resource has a few properties which are used by Tomcat, those are the auth, name, description, scope and type, from those name and type are required. Type is the actual type (fully qualified classname) it needs to create and the name is the jndi name relative to java:comp/env.

All the other properties specified on the Resource element are either used by the factory or the type created by the factory. So if you specify a property named username' in your Resource then there must be a get/set pair for that property on the type (i.e. setUsername/getUsername).

If we look at the mysql sample from the Tomcat documentation.

<Resource name="jdbc/TestDB" auth="Container" type="javax.sql.DataSource"
          maxActive="100" maxIdle="30" maxWait="10000"
          username="javauser" password="javadude"

We register a javax.sql.DataSource with the name jdbc/TestDB and the authentication is done by the Container. Now if we look further we see a few properties.

  • maxActive
  • maxIdle
  • maxWait
  • username
  • password
  • driverClassName
  • url

If we don’t specify an explicit type and/or a factory Tomcat uses its default implementation which is Apache Commons DBCP. For the default javax.sql.DataSource it uses also the default/basic implementation of that library, it uses BasicDataSource. If you study the javadoc of that class you will see a getter/setter pair for each of the properties named above.

Now lets put into practice all what we have learned here and try to configure a Mysql XA Capable datasource. We first need to specify the specific factory to use else the default factory will be used. The factory to use is the MysqlDataSourceFactory

Next we need to specify the type the factory needs to instantiate, we want a MySQL XA DataSource and thus we need to instantiate com.mysql.jdbc.jdbc2.optional.MysqlXADataSource. A list of the configurable properties can be found in the MySQL reference documentation.

<Resource name="jdbc/TestDB" auth="Container"
          user="javauser" password="javadude" explicitUrl="true"

And there we have it a configured XA Capable Mysql datasource. I think the MysqlDataSourceFactory can be improved a lot the same goes for the javadocs for the connector. However with a look at the sourcecode and a good understanding on how JNDI Resources can be configured in Tomcat it is quite easy to figure out how Resources can be configured.