HazelcastFactory in cellar blueprint xml

[Ryan Moquin <fr...@gmail.com>]

I noticed that in the cellar-hazelcast blueprint.xml, a factory is used to
instantiate the hazelcast instance.  I can see what that would be the case
considering how you have to construct a hazelcast instance.  What I was
wonder though, was why the factory is referenced by other components in the
xml to set their instance property?  Shouldn't there only be one instance
per jvm?  Wouldn't you just reference the service that was created with the
factory?  It appears as though the code is only allowing a single instance
to be created via the factory, so I wasn't sure if I was mistaken or if it
was a matter of preference to reference the factory.

It also made me wonder a little bit since the HazelcastGroupManager creates
a threadpool it looks like and receives what appears to be duplicate
notifications of the local configuration changing.  I just want to make
sure I'm understanding correctly. :)

Thanks!

Ryan

Re: HazelcastFactory in cellar blueprint xml

[rkmoquin <fr...@gmail.com>]

Gotcha the docs didn't make it super clear either.  I saw the thing about
partitioning though ... makes me wonder how much overhead there is to having
more than one hazelcast instance... seems like it might be a bit.....



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Re: HazelcastFactory in cellar blueprint xml

[Jean-Baptiste Onofré <jb...@nanthrax.net>]

Hi Ryan,

the purpose of the HazelcastFactory is to create a pre-configured 
hazelcast instance. It could be a singleton, but thanks to the Hazelcast 
partition manager and cluster isolation, it's possible to have multiple 
Hazelcast instances per JVM (even if we don't use it right now in Cellar).

For the HazelcastGroupManager, it's used for all cluster events (in 
collaboration with the HazelcastClusterManager), so it manages several 
incoming/outgoing cluster events, and manages several queues (one per 
group and per resource (features, bundles, etc)).

I hope it's clear ;)
Ping me on Skype if you want more details.

Regards
JB

On 05/28/2013 03:05 AM, Ryan Moquin wrote:
> I noticed that in the cellar-hazelcast blueprint.xml, a factory is used
> to instantiate the hazelcast instance.  I can see what that would be the
> case considering how you have to construct a hazelcast instance.  What I
> was wonder though, was why the factory is referenced by other components
> in the xml to set their instance property?  Shouldn't there only be one
> instance per jvm?  Wouldn't you just reference the service that was
> created with the factory?  It appears as though the code is only
> allowing a single instance to be created via the factory, so I wasn't
> sure if I was mistaken or if it was a matter of preference to reference
> the factory.
>
> It also made me wonder a little bit since the HazelcastGroupManager
> creates a threadpool it looks like and receives what appears to be
> duplicate notifications of the local configuration changing.  I just
> want to make sure I'm understanding correctly. :)
>
> Thanks!
>
> Ryan

-- 
Jean-Baptiste Onofré
jbonofre@apache.org
http://blog.nanthrax.net
Talend - http://www.talend.com