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From Lahiru Sandaruwan <lahi...@wso2.com>
Subject Re: Manual scaling effects are not persisted
Date Sat, 08 Nov 2014 16:35:09 GMT
Hi,

It seems we need to introduce cluster context(which will be persisted) for
keeping these runtime changes to policies and also the run time data such
as required count.

I will work on this.

Thanks.

On Sat, Oct 18, 2014 at 10:58 AM, Imesh Gunaratne <imesh@apache.org> wrote:

> Hi,
>
> @Raj: What I pointed out is a design issue. Each time we introduce a new
> feature we should not introduce new persistence logic unless unavoidable,
> rather persistence should happen centrally.
>
> In this scenario when we update the subscription it should go through a
> common flow and update the in memory data structure and persist the changes.
>
> @Lakmal: Yes definitely, will introduce a new feature to update policies.
> https://issues.apache.org/jira/browse/STRATOS-896
>
> Thanks
>
> On Wed, Oct 15, 2014 at 4:42 PM, Rajkumar Rajaratnam <rajkumarr@wso2.com>
> wrote:
>
>> Hi Imesh,
>>
>> On Wed, Oct 15, 2014 at 4:26 PM, Imesh Gunaratne <imesh@apache.org>
>> wrote:
>>
>>> I do not think we need to specifically handle this, manual scaling also
>>> need to take the same path as the standard scaling decision.
>>>
>>
>> Hmm.. In manual scaling what we are doing is increasing the min count
>> right? Basically we are modifying the cluster object which is already
>> created and added to the topology. Please be kind enough to explain me if I
>> got it wrong. How it can take the same path as standard scaling?
>>
>> Thanks.
>>
>>>
>>> On Wed, Oct 15, 2014 at 10:03 AM, Rajkumar Rajaratnam <
>>> rajkumarr@wso2.com> wrote:
>>>
>>>> Or else, we can have an API at CC side to update clusters and let CC to
>>>> publish ClusterUpdated event to topology topic. AS can simply listen to
>>>> this event and update the cluster context accordingly. Then we don't need
>>>> to introduce a new topic for AS to publish events and AS is already
>>>> listening to topology topic. IMO, this is a good approach.
>>>>
>>>> Wdyt?
>>>>
>>>>
>>>> On Wednesday, October 15, 2014, Rajkumar Rajaratnam <rajkumarr@wso2.com>
>>>> wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> As you know, we are now supporting manual scaling for docker
>>>>> containers. Autoscaler has an API to update cluster properties like min
>>>>> replicas of a particular cluster.
>>>>>
>>>>> void updateClusterMonitor(String clusterId, Properties properties)
>>>>> throws InvalidArgumentException;
>>>>>
>>>>> We are not persisting anything about clusters at AS side, when we
>>>>> shutdown stratos. When we are restarting, we are reading topology and
>>>>> create/populate/update cluster monitors.
>>>>>
>>>>> Hence this new value for min replicas is not persisted when we
>>>>> shutdown the stratos. During manual scaling the min replicas is updated
>>>>> only in AS side, hence if we restart the stratos, this effect will be
lost.
>>>>>
>>>>> So manual scaling should impact the topology. Here is a proposed
>>>>> solution.
>>>>>
>>>>> AS will provide an API to update cluster monitors, that is you can
>>>>> update properties of a cluster like min replicas. Once this API is called
>>>>> AS will send a *ClusterAltered* event to CC. Once CC gets this event,
>>>>> it will validate the properties, update the topology and send a
>>>>> *ClusterUpdated* event. Once AS gets this event, AS will update the
>>>>> cluster context with new values for properties like min replicas. Until
we
>>>>> get cluster updated event, AS will not alter any properties.
>>>>> Then everything is consistent and manual scaling effects will be
>>>>> persisted.
>>>>>
>>>>> wdyt?
>>>>>
>>>>> Thanks.
>>>>>
>>>>> --
>>>>> Rajkumar Rajaratnam
>>>>> Software Engineer | WSO2, Inc.
>>>>> Mobile +94777568639 | +94783498120
>>>>>
>>>>
>>>>
>>>> --
>>>> Rajkumar Rajaratnam
>>>> Software Engineer | WSO2, Inc.
>>>> Mobile +94777568639 | +94783498120
>>>>
>>>>
>>>
>>>
>>> --
>>> Imesh Gunaratne
>>>
>>> Technical Lead, WSO2
>>> Committer & PMC Member, Apache Stratos
>>>
>>
>>
>>
>> --
>> Rajkumar Rajaratnam
>> Software Engineer | WSO2, Inc.
>> Mobile +94777568639 | +94783498120
>>
>
>
>
> --
> Imesh Gunaratne
>
> Technical Lead, WSO2
> Committer & PMC Member, Apache Stratos
>



-- 
--
Lahiru Sandaruwan
Committer and PMC member, Apache Stratos,
Senior Software Engineer,
WSO2 Inc., http://wso2.com
lean.enterprise.middleware

email: lahirus@wso2.com blog: http://lahiruwrites.blogspot.com/
linked-in: http://lk.linkedin.com/pub/lahiru-sandaruwan/16/153/146

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