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From Matthieu Morel <>
Subject Re: PE instance creation
Date Tue, 17 Jan 2012 10:35:05 GMT
Hi Omkar,

On 1/17/12 5:59 AM, Banawalikar, Omkar IN BLR SISL wrote:
> 1.When a new value for key appears, S4 creates new instance of PE by
> cloning the prototype. But does it create one instance (for one key) for
> entire S4 cluster or it creates one instance per S4 node??

You have 1 PE instance per key per cluster (does not apply for keyless PEs).

In which node this PE lives is determined by the partitioning scheme 
(i.e. how do you distribute keyed events across the system)

> 2.Will there be one PN in each S4 node or multiple PN in each S4 node.
 > What does “PNs is a logical hosts to PEs” means??

My view of that is that you have physical S4 nodes, on top of which you 
can overlay networks of logical nodes. Usually you would have 1 PN per 
S4 node, but it would be possible to define another logical cluster that 
reuses some of the same physical nodes.

In a distributed setup with 1 logical cluster, you have _active_ S4 
nodes which are assigned a logical partition of the cluster (a PN) and 
receive and process corresponding events, and you may have _idle_ S4 
nodes that are in standby and do not initially participate in the 
processing; they do not initially host a logical PN.

You could also have a look at the Zookeeper configuration instructions 
to get more insight.

Hope this helps,


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