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From Emmanuel Lécharny <elecha...@gmail.com>
Subject Re: Question about Replication of Config Partition and Schema Partition
Date Tue, 10 Jul 2012 15:30:34 GMT
Le 7/10/12 5:07 PM, Göktürk Gezer a écrit :
>
>>> This is something we've postponed to discuss later, it's not a concern for
>>> single server but in replication scenario i'd like to know how this
>>> effects
>>> consistency between distinct server nodes. I'm not so sure what is being
>>> replicated in our implementation, some partition or entire server with all
>>> of its runtime components and configuration?
>>>
>> Depends. Replication is supposed to be configurable. You can replicate
>> only part of the data, it's up to the administrator to tell what should be
>> replicated, or not.
>>
> Well i don't believe replicating runtime information and plain data with
> the same process is a good idea anymore. Right now changes on configuration
> partition is read until next restart, but after migrating to OSGI it will.

You are right. I assumed that the configuration was propagated live, 
which means the Life Cycle management is already implemented in the 
server, which is not the case. However, it would be good to replicate 
the configuration, so that we just have to stop and restart the server 
to benefit from the modification, without having to inject it into the 
server.
> So syncing the replicas to have same runtime footprint must be handled via
> seperate subsystem, otherwise we're in trouble. There can be some switch in
> replication configuration to specify whether replica's runtime
> configuration will be the same.

Keep in mind that the configuration is read only once, at startup (at 
least, atm), so even if you modify the configuration, it's not effective 
before you stop and restart the server. So replication the configuration 
should not have any effect on the server, until you stop and restart it.


> Apart from configuration we also have the
> schema's backing that configuration entries, because they are not spread in
> many location, that won't be much of a problem.
>
> How replication is working for schema data ATM ?
Rplication is not working well, atm :/ For the schema or for the data...
>
>> In the standard scenario, the configuration and schema should be
>> replicated, that's pretty mandatory.
>>
> Configuration and configuration related schema must be handled in some
> other way, if don't then we can not manage lifecycle of server in OSGI.
Hmmm... The configuration schema cannot be modified. It's hard coded, 
and can't be changed.

> If
> some ApacheDS instance can obtain the reference to replica instance than we
> can manage it incrementally as the configuration or backed schema changes.
> ComponentHub is pretty much supporting that. However we should have access
> to DirectoryService reference of replica, I guess this is not the case
> right now?

Not sure I get whant you mean here...


-- 
Regards,
Cordialement,
Emmanuel Lécharny
www.iktek.com


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