use XML::Simple;
my $xml=XMLin("datei.xml") or die "$!";
for my $sesstion ($xml->{"MessageRoot"}->{Session})
{
 my $ci = $session->{clientIdentifier};
 my $dt = $session->{BncfInput}->{date};
 my $or = $session->{BncfInput}->{origin};
 my $cd = $session->{BncfInput}->{Code};
 my $nr = $session->{BncfInput}->{Nr};
 print "$ci : ($dt,$or,$cd,$nr)";
}