Re: Rep (2) : QUIPU vs X.500 (was: A tool for...)

[Skip Slone <[e-mail]>]

> A major interworking problem is the fact that QUIPU insists
> on the fact that the master entry of a relative root of a subtree
> is held by a different server than its direct subordinates.

Perhaps I'm misreading your analysis, but the way I read it this isn't quite 
true, although it is close to something I perceive as a potential problem.  
QUIPU does allow entries and their subordinates to be held in the same server 
(DSA).  For any "quipuNonLeafObject" entry, QUIPU requires a "masterDSA" 
attribute which contains the DN of the DSA holding its subordinates.  This may 
or may not be the DSA holding the entry itself.

What gets sticky is the issue of where the root of a subtree is actually 
mastered, especially when QUIPU is only on one side of the equation.  QUIPU DSAs
hold the master in the DSA containing all the siblings of that root (regardless 
of which QUIPU DSA holds the next level down in the subtree).  X.500 describes 
it differently -- the root of a subtree is held in the DSA holding the 
subordinate entries, and the root's superior holds a subordinate reference 
(which may or may not be an NSSR).

Both RFC 1276 and the QUIPU documentation discuss a concept called "spot 
shadowing" to handle what sounds like this kind of case (presumably for 
interaction with non-QUIPU DSAs lower in the DIT).  In the spot shadowing 
concept, the master of the entry can be held where X.500 describes it, and the 
QUIPU EDB holding the siblings of that entry (even if it's a "master" EDB) can 
hold a shadow (slave) copy of the entry.

What I haven't seen described anywhere is the case in which a non-QUIPU DSA is 
higher in the tree than a QUIPU DSA.  It would seem that the QUIPU DSA would 
expect the superior DSA to hold the master copy of its naming context.  If 
anyone knows, I'd appreciate some clarification.  It's not hard to trick QUIPU 
with bogus slave EDBs for superior entries, but how well it would interoperate 
may be another matter altogether.

I haven't experimented with either of these perspectives at all, so I can't 
share any experience.  And since I wasn't one of QUIPU's developers, I don't 
have any insight from that point of view.  Regardless, I hope this helps.

  -- Skip Slone