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https://issues.apache.org/jira/browse/STORM-121?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rick Kellogg updated STORM-121:
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Component/s: storm-core
> A hook should be able to modify a tuple
> ---------------------------------------
>
> Key: STORM-121
> URL: https://issues.apache.org/jira/browse/STORM-121
> Project: Apache Storm
> Issue Type: New Feature
> Components: storm-core
> Reporter: James Xu
> Priority: Minor
>
> https://github.com/nathanmarz/storm/issues/534
> High level:
> I should be able to add a field like “_trace” using a hook and have it be
> passed through the topology without having to change the rest of the
> topology. In this way a record can be followed through the topology and
> information about it’s process can be extracted.
> Want:
> https://github.com/maphysics/storm-starter/blob/trace_injector/src/jvm/storm/starter/ReverseStringTopology.java
>
> In the example topology linked above (which is on my fork of storm starter),
> the hook is looking for a field called _trace containing a hashmap. The idea
> is that somewhere in the topology that field is turned on and a hashmap is
> put in containing some basic starting information. In my example that was
> done in the spout and all the bolts emit an _trace field but really we want
> to be able to touch one bolt and add the field when a particular requirement
> is met. Then that field will continue with the record even when the
> OutputFieldsDeclarer does not have _trace as a field so that one does not
> have to edit each of the subsequential bolts.
> (This might be actually a how-to and not a bug in which case let me know and
> I’ll send it to the mailing list.)
> /cc @mrflip
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