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From Emmanuel Lecharny <>
Subject Re: Toward 2.0...
Date Sun, 04 Jan 2009 14:54:40 GMT
Tony Stevenson wrote:
> Emmanuel,
Hi Tony,
> It's good to see some of these things on the list.  However one or two 
> of these will be required should we decide to use ADS for the ASF.  I 
> know we will be able to get a good basic LDAP service in place without 
> some of these, *but* some are core requirements to the implementation 
> of ADS within the ASF.
I'm perfectly aware of that :) A LDAP server without replication is 
pretty useless, from a production POV.
> For example, the replication system will be one such core fundamental 
> requirement.  In fact we cannot really proceed a lot further with the 
> current demo/testing environment without it.  What state is it 
> currently in?
It's running. The concern we have about it is that we didn't used it 
_yet_ in a production environment (here the 'we' is Alex and me). We 
have to review it. However, two of our committers have worked on it, and 
one of them (Martin Alderson) has use the replication for its own 
project, after a few fixes, one year ago.

We also have integration tests, still running after thousands of 
commits, so I guess the replication system is still robust, as we didn't 
modified the tests.

The fact that replication has been mentioned into the 'Toward 2.0' list 
is because we want to be 100% sure that it works well, is solid, and 
covers all the corner cases. We also want to move the current 
implementation to something more versatile, based on the since added 
Change Log system. This is what we want to work on in the next 4 months.

But the next 2 weeks will be dedicated to check that Mitoses (the 
current replication code name) is working well.
> Also before LDAP goes live we will need some good basic documentation, 
> which I can certainly help produce.  These will mainly focus on system 
> runbooks, and who/what/where/how to make changes, stop/start services 
> etc.
We can work on that, for sure. As ADS is running as a daemon, it should 
be pretty easy to write the basic documentation.
> The DRS system is of interest to me. 
You bet a lot of people are interested in it !
> What happens at the moment if the system crashes?  
> Can we copy the flat files, daily, hourly?
> Would they be re-usable. i.e. Could I copy the data files, and could 
> they be used again if copied over the other files?   I am thinking 
> about a backup strategy for the LDAP data.
We do too. The think is that currently, we are relying on JDBM, and if 
the server crash severely well, you may lost some data. This is 
certainly not something we can accept. Now, this is the bad. About the 
good : a LDAP server is known to be read most of the time, and written a 
few. If we backup the JDBM files, hourly, we will be able to restart the 
server and only lost a few modification. The ChangeLog system will be 
extended in the next few days to write a journal (a LDIF file) in order 
to be able to restore the server state. As we have a unique revision 
number associated with each modification, a bit like subversion, we 
should be able to apply this journal starting at some specific point in 
the past we know to be good.

Those two features are for us the _most_ important things we want to 
work on, and we want to start working on it right now, in order to get a 
production ready server.

cordialement, regards,
Emmanuel L├ęcharny

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