Colin Robbins <> Thu, 12 March 1992 09:53 UTC

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From: Colin Robbins <>
Message-ID: <"9981 Wed Mar 11 09:25:22 1992">
Subject: SOS & LDBP

I have been reading OSI-DS 26 the Lightweight Directory Browsing
Protocol (LDBP) and OSI-DS 31 the Simple OSI Stack (SOS).

On its own, LDBP seems a reasonable thing to do (and I have even
suggested some minor improvements to the authors!)  However the purpose
of this mail is to ask if it is still needed in the light of SOS?

As I see it the call for LDBP came from Marshall Rose's work on the
DA-Protocol (dad in ISODE) and Tim Howes' work on DIXIE.  Both of
these provide access to the Directory using a protocol that requires
much less resource than full DAP.  These were developed because the
was a genuine need.  

At the San Jose OSI-DS meeting last September, it was suggested that a
unified lightweight protocol was needed, and so LDBP was developed.
LDBP provides a cut down version of the X.500 DAP protocol, with
a simplified form of BER encoding.

( I have a slight doubt that this is the right approach.  If you are
going to cut down a protocol, why not just define a profile.
e.g., we'll use the X.500 DAP  bind, search, modify and unbind
operations only, simple authentication only, the following optional DAP
fields will not be used...)

SOS is a much more general than LDBP, and describes a more general
lightweight approach for the full OSI stack.  Appendices A and B of
this document describe two example SOS nameservices protocols, based
upon X.500, and something similar the LDBP could easily envisaged.

So, we now have two documents describing different solutions to the same
problem - the need for simplified access to the OSI directory.

SOS will take longer to "hit the streets" than LDBP, it involves a lot
more work.  However when it arrives, there is a possibility, it will
make LDBP redundant.  So, it it worth spending effort on LDBP now,
when the DA-Protocol and DIXIE will fill the gap until SOS arrives.

Alas, I will not be at the OSI-DS meeting in San Diego, so will not be
able to raise this question myself.  I am not sure of the answer, but
think it merits some discussion in your meeting.