Hi Grainier,
*FrequentWindowProcessor* is based on Misra-Gries counting algorithm.
Parameter: sizeOftheMap + key to group the events (If no keys are given the
concatenation of all the attributes of the event is considered as the key)
We keep a map of (key,counter)
Whenever an event comes,
generate the key based on the parameters given
check the map for that key.
if the key is already in the map increment the
count by 1; add event to the window ; remove the old event corresponding to
the key from the window
else if it's not there
if map size <=
sizeOftheMap add a new entry to the map with (key,count=1); add event to
the window
else if size >
sizeOftheMap
decrement the
count stored in the map by 1 for all the entries
remove all the entries which has count 0 from the map and from the window
if count of
none of the entries in the map becomes 0, discard the new event
else add the
new entry to map with (key,count=1) ; add event to the window
*LossyFrequentProcessor* - based on Lossy Counting algorithm is also for
frequency counts
Parameters: support threshold, error bound, key to group the events (If no
keys are given the concatenation of all the attributes of the event is
considered as the key)
In this algorithm events are divided into buckets.
We keep a map of (key, lossycount [bucket id, count] )
Whenever an event comes,
calculate the bucketId
generate the key based on the parameters given
check the map for that key.
if the key is already in the map increment the
count by 1;
else if it's not there add a new entry to the map
with (key,[bucketId,1])
event removal and insertion to the window is done
based on the user given parameters. (You can check the code for the exact
conditions)
Thanks,
Sachini
On Wed, Sep 23, 2015 at 1:04 AM, Grainier Perera <[email protected]> wrote:
> Hi Sachini,
>
> Could you provide a small description on the functionality, parameters and
> return types of Frequent window processor and Lossy frequent window
> processor of Siddhi inbuilt windows?
>
> Thanks,
> Grainier.
> --
> Grainier Perera
> Software Engineer
> Mobile : +94716122384
> WSO2 Inc. | http://wso2.com
> lean.enterprise.middleware
>
--
*Thanks & Regards,Sachini JayasekaraSoftware Engineer; **WSO2 Inc. *
*lean . enterprise . middleware | http://wso2.com <http://wso2.com> *
Mobile : +94712371165
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