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Re: [ldap-nis] alias

"Kurt D. Zeilenga" wrote:

> An alias just allows a DN to refer to some other object.
> The alias itself only contains the minimal information
> needed (namely the name of the aliased object).
> There is no standard track representation of aliases in LDAP.
> OpenLDAP approach is to use "named aliases" (similar to
> "named references").  Unfornately, I haven't had time to
> write an I-D detailing our approach.

I remember at some point I had a similar need: to have
kinda aliases in entries that resulted in merging the entry's
attributes with those of the aliased objects. This sort of
data-oriented join (although out of any protocol) may be
a useful feature. It may be implemented as an active
"seeAlso" that could be explicitly required by the client.

> LDAP, the protocol, provides no join mechanism.  Some
> servers may provide such... that's part of what "meta"
> directories are about.  I note that back-meta (HEAD only)
> is our experimental work in this area.

There are many different ways to implement a join mechanism
in what is usually called a "meta" directory (the definition
is rather fuzzy). In this case, the join would be data-oriented,
since the entry itself would contain the links to other data
(possibly on other servers), making things easier to some extent,
at the risk of incurring in consistency problems (what happens
if the  referenced entry does not exist any more? Note that
the same applies to aliases and actually the analogous
of the 'aliasDereferencingProblem' error should be raised).
What I've been working in back-meta is a more dynamic
criterium of dn renaming/chasing that add no join capability.
I'd rather think of join criteria as delegated to agents that keep
in sync a "meta" directory (storing a copy of the joined data)
in an asynchronous manner (basically for performance issues).


Dr. Pierangelo Masarati               | voice: +39 02 2399 8309
Dip. Ing. Aerospaziale                | fax:   +39 02 2399 8334
Politecnico di Milano                 | mailto:masarati@aero.polimi.it
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