Re: [JBoss-dev] Partition merge and service state merge algorithm

[Bela B. <be...@ya...>]

Sacha Labourey wrote:

> Hello Bela,
>
> Yes, we need some kind of policy. But I thought about something a 
> little bit
> different. In fact, there is already a way for services that have state to
> know about partition merging and plug into it. Instead I thought about a
> policy where you can receive events when you are no more "on the good 
> side"
> (defined by the policy) of the network partition. This could be, for
> example, access to a common DB, some data in a common DB, the minimal size
> of the partition, etc. As long as the policy is not satisfied, the service
> would be in stand-by.


You are talking about a primary-partition approach. The literature tells 
you to shut down members in a non-primary partitions. It is simple to 
implement, all right. But it reduces overall availability of a 
distributed system, that's why there are many approaches beyond primary 
partition in research. But regardless of whether we want to have 
progress or shutdown on a partition, we need to present to the user a 
choice. E.g. shut down, continue and merge later etc. This way we can 
implement both approaches.

-- 
Bela Ban
www.javagroups.com
(408) 316-4459