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From "Dale LaBossiere (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QUARKS-107) Add sample use of new Range class in recipe3 - detect value out of range?
Date Tue, 05 Apr 2016 17:27:25 GMT

    [ https://issues.apache.org/jira/browse/QUARKS-107?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15226711#comment-15226711
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Dale LaBossiere commented on QUARKS-107:
----------------------------------------

The initial pull updates "recipe_value_out_of_range.md".

I have two new recipes in the works that I'll push separately:
- recipe_external_filter_range.md:   "Using an external configuration file for filter ranges."
- recipe_adaptable_filter_range.md:  "Dynamically changing a filter range"

> Add sample use of new Range class in recipe3 - detect value out of range?
> -------------------------------------------------------------------------
>
>                 Key: QUARKS-107
>                 URL: https://issues.apache.org/jira/browse/QUARKS-107
>             Project: Quarks
>          Issue Type: Improvement
>            Reporter: Dale LaBossiere
>            Assignee: Dale LaBossiere
>              Labels: newbie
>
> Add sample use of new Range class in recipe3 - detect value out of range?
> Either or both of the recipe's existing samples could be use Range, or one of them could
be cloned to use it.
> ```
> TStream<Double> simpleFiltered = temp.filter(tuple ->
>             tuple < TEMP_LOW || tuple > TEMP_HIGH);
> // could be
> TStream<Double> simpleFiltered = temp.filter(Ranges.open(TEMP_LOW, TEMP_HIGH);
> TStream<Double> deadbandFiltered = Filters.deadband(temp,
>             identity(), tuple -> tuple >= TEMP_LOW && tuple <= TEMP_HIGH);
> // could instead be
> TStream<Double> deadbandFiltered = Filters.deadband(temp,
>             identity(), Ranges.closed(TEMP_LOW, TEMP_HIGH));
> ```
> Use of a Range simplifies the code a bit.  I can also avoid mistakes if one's code "duplicates"
the expressions for a particular range in multiple places.  
> Using Range can be more compelling for the simplicity with which a range may be expressed
and created from a config file for an app.  e.g. imagine how one would express the range in
a Properties config file.  A range property value in a Properties file would simply be:
> ```
> # my sensor filter range
> myFilterRange=[71.0..98.0]
> ```
> and the app code to create the Range would simply be:
> ```
> Range<Double> myFilterRange = Ranges.valueOfDouble(props.getProperty("myFilterRange"));
> ```
> Another compelling case is making a filter range dynamically changeable, for example
as a result of some received IoT "device command".  The range could be declared like:
> ```
> AtomicReference<Range<Double>> myFilterRange = new AtomicReference<>(
>     Ranges.valueOfDouble(props.getProperty("myFilterRange"));  // initial range value
> // code in the device's set-filter-range cmd handler is ultimately:
> //   myFilterRange.set(Ranges.valueOfDouble(the-new-range-string-from-the-cmd));  //
sets a new Range object
> // Using the changeable filter range is simply:
> TStream<Double> simpleFiltered = temp.filter(myFilterRange.get());
> ```
> Dynamic filter Predicates is probably a good recipe unto itself :-)



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