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https://issues.apache.org/jira/browse/QUARKS-150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15250467#comment-15250467
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Dale LaBossiere edited comment on QUARKS-150 at 4/20/16 6:38 PM:
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Valve, tests and recipe delivered
was (Author: dlaboss):
Valve and recipe delivered
> add Valve Predicate
> -------------------
>
> Key: QUARKS-150
> URL: https://issues.apache.org/jira/browse/QUARKS-150
> Project: Quarks
> Issue Type: New Feature
> Reporter: Dale LaBossiere
> Assignee: Dale LaBossiere
>
> A Valve Predicate accepts tuples when its state is {@link State#OPEN},
> otherwise it rejects tuples.
> A valve is typically used to dynamically control whether or not
> some downstream tuple processing is enabled. A decision to change the
> state of the valve may be a result of local analytics or an external
> device command.
> [ fwiw, this is known as a 'Switch' utility operator in IBM Streams ]
> Maybe this belongs in quarks.topology.plumbing/PlumbingStreams, not
> quarks.analytics.sensors/Filters like Deadband and Deadtime, since there's
> not really much "analytic" about it?
> E.g., a Valve might be used to control whether or not logging of tuples is
> enabled.
> ```
> TStream<JsonObject> stream = ...;
>
> Valve<JsonObject> valve = new Valve<>(Valve.State.CLOSED);
> stream.filter(valve).sink(someTupleLoggingConsumer);
> // from some analytic or device command handler...
> valve.setState(Valve.State.OPEN);
> ```
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