MyEJBThatUsesCassandraDS.java

@Stateless
public class MySessionBean {

    @Resource(name="CassandraDS", mappedName="java:jboss/datasources/CassandraDS")
    private DataSource dataSource;

    @TransactionAttribute(TransactionAttributeType.NOT_SUPPORTED)
    public void useCassandraDS() {
        try {
            Connection connection = dataSource.getConnection();
            ...
        } catch (Exception e) {
            // handle exceptions
            ...
        } finally {
            // close statements, connections
        }
    }

}