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From Matthieu Morel <mmo...@apache.org>
Subject Re: How to split a stream
Date Mon, 20 Feb 2012 12:35:23 GMT
On 2/19/12 7:18 AM, Jia Ding wrote:
> Hello everyone,
>
> I'm a beginner of s4.
> Now I've a question about how to split a event stream.
> e.g.
> There is a raw event stream, named RawStream.
> It contains two different events: event with name "a" and "b".
>
> RawStream looks like:
> {"id":100, "name":"a", "value":3}
> {"id":200, "name":"b", "value":1}
> {"id":100, "name":"a", "value":16}
> {"id":100, "name":"a", "value":24}
> {"id":200, "name":"b", "value":7}
> {"id":100, "name":"a", "value":100}
> {"id":200, "name":"b", "value":59}
>
>
> I want to implement a PE, which can process the RawStream, and separate
> it into two streams: StreamA (events with name "a") and StreamB(events
> with name "b").
>
> Now the problem is, in the configuration,
> one PE can only define one "outputStreamName".
> Is it means for one PE, can only output to one stream?
> How can it output to two streams?

You are probably referring to some examples in the tutorial when stating 
there is only 1 output stream name.

But you can actually specify several output stream names in the Spring 
configuration, you just need to adapt the way you specify them. Then 
from your code in the PE, use something like:
"dispatcher.dispatchEvent(streamName1, newEvent);"
"dispatcher.dispatchEvent(streamName2, newEvent);"

You could even inject different dispatchers with different partitioning 
schemes if needed.

Hope this helps,

Matthieu

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