how to set HTTP error via Apache SOAP API?

Hi,
  I need set a HTTP Error (401)
I  have tried to set error on server side  through HttpServletResponse, that
I extract from response context(SOAPContext resCtx)
If I use the follows code
HttpServletResponse rs = (HttpServletResponse)
resCtx.getProperty(Constants.BAG_HTTPSERVLETRESPONSE);
         rs.sendError(401);

But my client get a SOAP Fault (SOAP-ENV:Fault). And I have not the
possibility to check through SOAP API  if Http Error was send (sometrhing
like HttpServletResponse rs, rs.isHttpError()).
Or are there the possibility to check this?
Thanks
Julia