+1 Yes a good point Lakmal, to reduce the latency for a modification to
propagate to all the instances we might need to replicate topology as well.

Thanks

On Wed, Nov 26, 2014 at 2:44 PM, Lakmal Warusawithana <lak...@wso2.com>
wrote:

>
>
> On Wed, Nov 26, 2014 at 1:16 PM, Imesh Gunaratne <im...@apache.org> wrote:
>
>> ​Hi Devs,
>>
>> This is to discuss the clustering model of the cloud controller:
>>
>>
>> ​
>>
>> As shown in the above diagram the idea is to have a coordinator node to
>> handle data persistence logic and message publishing (topology, instance
>> status, etc). The coordinator will be selected randomly and at a given time
>> there will be only one coordinator. If the existing coordinator node goes
>> down, another member will become the coordinator automatically (similar to
>> carbon clustering agent).
>>
>> According to this design Autoscaler (AS)/Stratos Manager (SM) will talk
>> to Cloud Controller (CC) via the Cloud Controller Service endpoint exposed
>> via the load balancer.
>>
>> *Data Replication*
>> When a request comes into one of the CC instances it will execute the
>> necessary actions and update the data holder and/or topology which is in
>> memory. At this point the data holder changes will be replicated to other
>> instances using a distributed map. Once the coordinator receives the above
>> updates it will persist the changes to the registry database.
>>
>> In this design we might not need to replicate the topology since it is
>> already there in the message broker. The idea is to let coordinator publish
>> the topology changes and the other members to listen to it.
>>
>>
> IMO, we may need to replicate topology also, otherwise it may occur some
> inconsistency.
>
>
>> Please add your thoughts.
>>
>> Thanks
>>
>>
>> --
>> Imesh Gunaratne
>>
>> Technical Lead, WSO2
>> Committer & PMC Member, Apache Stratos
>>
>
>
>
> --
> Lakmal Warusawithana
> Vice President, Apache Stratos
> Director - Cloud Architecture; WSO2 Inc.
> Mobile : +94714289692
> Blog : http://lakmalsview.blogspot.com/
>
>


-- 
Imesh Gunaratne

Technical Lead, WSO2
Committer & PMC Member, Apache Stratos

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