[infinispan-dev] ISPN-200

[Manik Surtani]

On 9 Jun 2010, at 05:45, Israel Lacerra wrote:

> Manik,
> 
> About the "map" part of the map/reduce of ISPN-200.
> 
> Looking in the code, my intention is(briefly) create a ReplicableCommand in CacheQueryImpl and then use RpcManager to make the query on all nodes. 
> 
> But ISPN-200 depends on ISPN-39, right?

Well, not precisely.  They are related and a degenerate case of ISPN-39 *could* work for you, but isn't necessary.  Let me explain:

ISPN-39 is about pushing tasks to nodes based on key.  So, you may say something like, here's a task, T, which requires keys K1, K2, K3.  The DistributionManager could then be used to determine the most appropriate node(s) to send T to, and process it there.

Now in the case of ISPN-200, you don't know which nodes contain the entries you are looking for.  So you would need to broadcast the task, T, which in this case is a query task, to *all* nodes.  So while it is similar to ISPN-39 in that it executes remote tasks, the logic of determining which nodes to execute the task on is different - you would need to execute the task on all nodes all the time.

Hope this clarifies things a bit.  :)

Cheers
Manik

> This dependecy is about the map part? The idea behind ISPN-39 is to migrate a computation to other nodes? Like a "continuation"? And then ISPN-200 will use this api to make the query on all nodes? 
> 
> 
> thanks!
> 
> Israel
> 
> 
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--
Manik Surtani
manik at jboss.org
Lead, Infinispan
Lead, JBoss Cache
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