code: public ExtensionHandler launch()
      throws TransformerException
    {
      ExtensionHandler handler = null;
      try
      {
        Class cl = ExtensionHandler.getClassForName(m_handlerClass);
        Constructor con = null;
        //System.out.println("class " + cl + " " + m_args + " " + m_args.length + " " + m_sig);
        if (m_sig != null)
          con = cl.getConstructor(m_sig);
        else // Pick the constructor based on number of args.
        {
          Constructor[] cons = cl.getConstructors();
          for (int i = 0; i < cons.length; i ++)
          {
            if (cons[i].getParameterTypes().length == m_args.length)
            {
              con = cons[i];
              break;
            }
          }
        }
        // System.out.println("constructor " + con);
        if (con != null)
          handler = (ExtensionHandler)con.newInstance(m_args);
        else
          throw new TransformerException("ExtensionHandler constructor not found");
      }
      catch (Exception e)
      {
        throw new TransformerException(e);
      }
      return handler;
    }
docs: Launch the ExtensionHandler that this ExtensionNamespaceSupport object defines.