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From "Liviu Tudor (JIRA)" <>
Subject [jira] [Commented] (SANDBOX-341) [functor] New components: summarize and aggregate
Date Mon, 12 Sep 2011 15:18:08 GMT


Liviu Tudor commented on SANDBOX-341:

Hi Simone,

Agreed on not needing the {{evaluate()}} function -- really it was included there so I can
have the JavaDoc section for it -- but I've moved that in the class header.
Will make the changes to use getters/setters for abstract classes; meanwhile though, to help
me address all the checkstyle/findbugs issues, can you point me in the right direction as
to how to run the findbugs/checkstyle against the code and where would I find the results?
(sorry a bit new to the whole maven setup -- and luckily in most environments i've used it
so far, I relied on the automated hudson/integration to produce these nightly reports :)
With regards to the document under {{src/site/xdocs}} -- what should this include? A high
level overview of the components and possibly including sample code maybe with patterns of
usage? Or what things should I touch on?
One last thing, going back through your comments, I've only just noticed a small discrepancy
-- you have asked me to add myself to the list of developers in the {{pom.xml}} -- I opted
to put myself on the contributors list as I'm guessing _developers_ would be the Apache peeps
actually maintaing/managing this project, right? Not a big thing really, just trying to iron
out all the small details at the moment, so thought I'd ask about this as well.
Sorry to be a pain!

> [functor] New components: summarize and aggregate
> -------------------------------------------------
>                 Key: SANDBOX-341
>                 URL:
>             Project: Commons Sandbox
>          Issue Type: Improvement
>          Components: Functor
>         Environment: JDK 1.6.0_25 but should work with any JDK 5+ (possibly 1.4 though
I haven't tested).
>            Reporter: Liviu Tudor
>            Priority: Minor
>              Labels: features
>         Attachments:, commons-functor.patch.bz2
> This is the next step from -- as instructed
I'm finally hoping to get the code in the right place and hopefully this is something that
the functor component could do with.
> Whereas initially I just started with the summarizer component, I have added now the
second one, the "aggregator" as they are somehow related. If this code proves to be useful
to functor in any way, it would actually be good to get some feedback on these 2 to see if
the class hierarchy can in fact be changed to share some common functionality as I feel (probably
due to the similar needs that lead to writing/using these components) that somehow they should
share a common base.
> In brief, the 2 components:
> * aggregator: this just allows for data to be aggregated in a user defined way (e.g.
stored in a list for the purpose of averaging, computing the arithmetic median etc). The classes
provided actually offer the implementation for storing data in a list and computing the above-mentioned
values or summing up everything.
> * timed summarizer: this is another variation of the aggreator, however, it adds the
idea of regular "flushes", so based on a timer it will reset the value and start summing/aggregating
the data again. Rather than using an aggregator which would store the whole data series (possibly
for applying more complex formulas), this component just computes on the fly on each request
the formula and stores the result of it. (Which does mean things like computing arithmetic
mean, median etc would be difficult to compute without knowing upfront how many calls will
be received -- i.e. how many elements we will be required to summarize/aggregate.) So the
memory footprint of running this is much smaller -- even though, as I said, it achieves similar
results. I have only provided a summarizer which operates on integers, but obviously others
for float, double etc can be created if we go ahead with this design.
> Hopefully the above make sense; this code has resulted from finding myself writing similar
components to these a few times and because it's always been either one type (e.g. aggregator)
or another (summarizer) I haven't given quite possibly enough thought to the class design
to join these 2. Also, unfortunately, the time I sat down to make these components a bit more
general and submitted issue 340 was nearly 3 months ago so I'm trying to remember myself all
the ideas I had at a time so bear with me please if these are still  a bit fuzzy :) However,
if you can make use of these I'm quite happy to elaborate on areas that are unclear and obviously
put some effort into getting these components to the standards required to put these into
a release.

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