Re: Making copies of attribute values

[Piotr Wadas <pwadas@dtpw.pl>]

On Mon, 26 Oct 2009, Ravi Verma wrote:

> Dear Friends,
> 
> I have a need to extend an LDAP schema by adding an attribute and copy the
> value from an existing attribute to it. We need to keep the two copies of
> the attribute values in synch. It is a kind of replication where it is
> replicating one attribute into another in the same record.

Note, that no matter what kind of mechanism (internal, external, 
whatever), AFAIK it's not possible to have two variables of the particular
attribute with the same value. Anyway, to achieve such functionality,
I'd try the following:

Let's say you need to keep copy of three multivalue attributes per-entry,

commonName: john
commonName: fitzgerald
commonName: kennedy
mail: j@whitehouse.gov
mail: jfk@pentagon.org
uidNumber: 12345


1) customize schema adding e.g. commonNameCopy, mailCopy, uidNumberCopy 
attributes, with the same attribute properties

2) use some quick&dirty ldapmodify script, called from cron every 5 
minutes, applying attribute copying for some cute ldap filter.

This is quite simple and easy to achieve, I don't know whether
some other methods like internal overlay doing this, is available.
Anyway, the only reason to keep attribute value copy is (probably),
to find out what was a previously set value for particular attribute,
and possibly restore (?) a previously set value. While copying 
(synchronizing) attribute value with its copyTwin attribute,
actually make previously set value - lost. So the reason and objective
of the whole thing would also need some attribute-value-timestamp
stored somewhere/somehow per-value, which, actually, makes the whole
concept a bit out of sense.

Regards,
DT

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