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From "Norval Hope" <nrh...@gmail.com>
Subject Re: [ApacheDS] [Schema] New schema subsystem specification
Date Thu, 23 Nov 2006 02:49:47 GMT
Hi Alex,

Looks like interesting stuff, and addresses some of the problems I had
noticed but didn't have the knowledge to resolve (e.g. bootstrap v.
global registries).

I do have a few comments to make from my biased "ApacheDS used to
house third party custom partition" point-of-view:
  1. I'd be much happier if the ".schema file => schema partition"
tool were instead (or also) available as an optional start-up
mechanism activatable by uncommenting support in server.xml. In the
use-cases dear to my heart users are able to easily register dynamic
custom partitions along with the .schema files they depend on by
simply placing files in various filesystem directories (ala
appservers) rather then having to run separate utilities. Given this
point I'd most probably do away with a maven plugin for the ".schema
=> schema partition" bit and replace it with code to determine whether
the .schema partition needed to be populated with bootstrap
information on its first run after deployment (from .schema files
included in a release .jar). For dynamic updates/additions of .schema
files the relevant filesystem directories could be polled for changes
periodically (again ala appservers).
  2. Being able to change schema information is a very power-user
feature, but I'd imagine that a much more common usage is simply
wanting to add extra read-only schema information (matching various
RFCs and/or basically static schemas defined by third party vendors)
after deployment. In my usecases storing the thirdparty (i.e.
non-core) schema information persistently is actually a minus rather
then a plus; I'd prefer my users could deploy another custom partition
with updated schema information and restart AD without having to worry
about clashes with existing information. Is it theoretically possible
to indentify various schema subtrees as "read-only" so that they can't
be changed and aren't persisted, but are instead transiently populated
from .schema files at start-up?
  3. Whether modifying schema information via piece-meal updates or
whole .schema file imports, we face questions re versioning / draining
of pending requests referring to old version of the schema etc. Is the
race condition between schema changes and other operations referring
to the schema some that needs to be considered now, say by
synchronizing access to the schema partition.

I know my focus is out of whack with AD's primary objectives, in that
I don't use it as a persistent store at all, but even so I see
populating at start-up rather then maven plugin + import utility as a
universal plus in terms of flexibility / amount of code required.

Thanks

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