LDAP (Lightweight Directory Access Protocol) is a means by which a TCP/IP based database(s) are accessed.

.oO(I'm sure I'm teaching my granny to suck eggs, but here goes anyway...)

As far as hierarchy is concerned, why not fall back on the inheritance of methods, accessors & mutators e.g. in your example, Desk->method() resulting in Workflow->method() actually being the method called - thus indirectly implementaing the inheritance of permissions etc. e.g.

package Workflow;

sub method {
  my $self = shift;
  .
  .
  .
}

package Desk;

use base qw/Workflow/;

sub new { bless \( my $scalar ), ref $_[0] || $_[0] }

package main;

my $desk = Desk->new();

$desk->method();
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etc. etc.