On Jul 4, 2013 6:39 PM, "Isuru Haththotuwa" <[email protected]> wrote:
>
> Hi,
>
> On Thu, Jul 4, 2013 at 5:44 PM, Afkham Azeez <[email protected]> wrote:
>>
>> There could be a situation where when a cluster message is sent, a
member momentarily leaves the cluster, but joins immediately. This
generally could happen when the nodes slow down under load, or due to
intermittent network failures. However, this could lead to failures because
crucial cluster messages may not be received by members.
>>
>> To overcome this, or reduce the probability of loss of such messages, we
can replay a certain number of messages when a member joins. On the sender
side, messages over a particular time period can be buffered, and then
replayed when new members join. However, we should ensure that the messages
are idempotent, and messages should declare whether they are idempotent or
not. If a message is not idempotent, we will not replay it. All the
messages we have at the moment are idempotent, AFAIK.
>>
>>
>> How does this approach sound?
>
>
> +1. IMHO it is cleaner if we can replay a sequence of cluster messages
node which originally was a member of the cluster, and then got removed
(due to a network failure, etc) and got re-joint before a certain time
period. If we replay a set of messages whenever a new member joins, isn't
there a possibility that a newly joined member is updated to a false state?

We can have sequence number in the messages so the message-receiver can
drop the duplicate messages

Suho
>>
>>
>> --
>> Afkham Azeez
>> Director of Architecture; WSO2, Inc.; http://wso2.com
>> Member; Apache Software Foundation; http://www.apache.org/
>>
>> email: [email protected] cell: +94 77 3320919
>> blog: http://blog.afkham.org
>> twitter: http://twitter.com/afkham_azeez
>> linked-in: http://lk.linkedin.com/in/afkhamazeez
>>
>> Lean . Enterprise . Middleware
>>
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>
>
>
> --
> Thanks and Regards,
>
> Isuru H.
>
>
>
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