my $call = $wsdl->compileClient($operation
     , transport_hook => \&basic_auth );
  sub basic_auth($$)
  {   my ($request, $trace) = @_;

      # Encode userid and password
      my $authorization = 'Basic '. encode_base64 "$user:$password";

      # Modify http header to include basic authorisation
      $request->header(Authorization => $authorization );

      my $ua = $trace->{user_agent};
      $ua->request($request);
  }