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Date: Mon, 26 Jan 2009 11:27:24 +0100
Message-ID: <d45b08f00901260227t7b4f91f5t4a934c53c9472319@mail.gmail.com>
Subject: Re: [DRS] Changelog improvements
From: Emmanuel Lecharny <elecharny@gmail.com>
To: Apache Directory Developers List <dev@directory.apache.org>
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Hi David,

> I'm not sure exactly what the requirements here are but a couple of exist=
ing
> projects that might provide a usable journal/log:
>
> objectweb howl is a transaction log, basically its designed to write
> "prepare" entries that have some data and "commit" entries that say the d=
ata
> is no longer relevant.  I imagine you could write the ldif entry as the
> "prepare" record and some indication of all replicas being up-to-date as =
the
> "commit" entry.

That's something we might check, as it may alleviate the burden of
writing our own wheel...

> activemq has quite a few journal/log schemes.  I think that they are most=
ly
> using kaha.  I'm don't understand all the features but think that it woul=
d
> do everything you need.  IIUC typically the messages themselves are writt=
en
> to one "database" and for each subscription an index entry is written to =
a
> related reference database.  As the acks come in for the subscriptions th=
e
> index entries are removed and after all deliveries have happened the main
> entry is removed.

Another project to look at.


> I imagine you could implement the whole replication scheme using activemq
> embedded brokers on each server but this might not be the most performant
> implementation.

Regarding activeMQ, atm, nothing has been decided. We thought about
using a JMS system to manage replication, as it offrs a reliable
asynchronous system to communicate between servers. We have to go a
bit further in the requirements, nothing is really stabilized atm.
--=20
Regards,
Cordialement,
Emmanuel L=E9charny
www.iktek.com