* from this factory
     * @throws IllegalArgumentException if the role or ui is neither
     * one of the standard ones, nor a private one
     * supported by the factory.
     */
    public abstract Object getUI(int role, String ui) ;

    /** 
     * Given a UI role obtained from this factory obtain the UI
     * types available from this factory which implement this role.
     * The returned Strings should refer to the static variables defined
     * in this class so that applications can use equality of reference
     * ("==").
     * @param role to be looked up.
     * @return the UI types supported by this class for the specified role,
     * null if no UIs are available for the role.
     * @throws IllegalArgumentException is the role is a non-standard
     * role not supported by this factory.
     */
    public abstract String[] getUIClassNamesForRole(int role) ;

    

}