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From Achim Nierbeck <bcanh...@googlemail.com>
Subject Re: [PROPOSAL] Cellar behaviour change for Cellar 2.3.4/3.0.1/2.4.0/4.0.0.M1
Date Tue, 11 Nov 2014 13:46:01 GMT
Hi JB,

+1 from my side, cause right now the sync issue is more then annoying.
Sometimes the complete cluster starts to swing back and forth between start
and stop eventually crashing.

regards, Achim

2014-11-11 14:41 GMT+01:00 Jean-Baptiste Onofré <jb@nanthrax.net>:

> Hi all,
> Currently, we see some annoying side effects when using Cellar (with its
> default configuration), especially some bundles stopped whereas they should
> not, and sync issue when new nodes join.
> I would like to propose the following change in the Cellar behaviour:
> 1/ Currently, Cellar use "listeners" that get the local node changes (like
> installation of a bundle, a feature, etc), and broadcast the changes to the
> entire cluster. The problem with that is that it sync "bad" events (like
> bundles stop when you stop the node for instance). I would like to disable
> the listeners by default, and "force" the users to use the cluster:*
> dedicated commands to update the cluster state.
> Of course, the user can use a flag to enable the listeners, but at his own
> risk ;)
> 2/ When a new node joins the cluster, Cellar uses a synchronizer (per
> resource, one for features, one for bundles, etc) to "merge" the local node
> state and the cluster state (it's push/pull for the state). But, actually,
> this "merge" doesn't really make sense for joining node. I think the first
> node of the cluster should push his state to the cluster, but the new
> joining nodes state should be overwritten by the cluster (the cluster
> should be the master). I propose to introduce a configuration flag defining
> who is the master (cluster or node): if it's the cluster, the synchronizer
> overwrites the local node state with the cluster state, if it's the node,
> the synchronizer overwrite the cluster state with the local node state.
> 3/ I added new HTTP support in Cellar, allowing to sync the HTTP session
> and load balance the request on the different nodes of the cluster. I will
> blog about this to explain how it works.
> 4/ I added also some new centralized feature in Cellar (like central log
> view, etc). I will blog about this as well.
> I already created the Jira about that.
> My question is more about the Cellar 2.3.4 and 3.0.1 releases. I think it
> makes sense to include those changes asap so that's why I would like to
> push (of course documenting and announcing the changes) in the next Cellar
> minor releases.
> WDYT ?
> Thanks
> Regards
> JB
> --
> Jean-Baptiste Onofré
> jbonofre@apache.org
> http://blog.nanthrax.net
> Talend - http://www.talend.com


Apache Member
Apache Karaf <http://karaf.apache.org/> Committer & PMC
OPS4J Pax Web <http://wiki.ops4j.org/display/paxweb/Pax+Web/> Committer &
Project Lead
blog <http://notizblog.nierbeck.de/>
Co-Author of Apache Karaf Cookbook <http://bit.ly/1ps9rkS>

Software Architect / Project Manager / Scrum Master

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