Not using the java: namespace<local-tx-datasource> 
<jndi-name>GenericDS</jndi-name>
<use-java-context>false</use-java-context>
<connection-url>[jdbc: url for use with Driver class]</connection-url> 
<driver-class>[fully qualified class name of java.sql.Driver implementation]</driver-class> 
<user-name>x</user-name> 
<password>y</password> 
</local-tx-datasource>