I have given some feedback on the gsoc site. Suho
On Mon, Mar 27, 2017 at 9:03 PM, Gobinath <slgobin...@gmail.com> wrote: > Hi all, > > Thanks. I have shared the draft of my proposal titled "Non-Occurrence of > Events for Siddhi Patterns" with WSO2 through GSoC dashboard and requesting > your feedback on this. > > > Thanks & Regards, > Gobinath > > On Wed, Mar 15, 2017 at 1:30 PM, Sriskandarajah Suhothayan <s...@wso2.com> > wrote: > >> Thanks for the GSoC idea, I hope this will be a good way to improve the >> Siddhi language and make it more powerfull. >> If time permits we can also add other use-cases of patterns & sequences >> and improve it further. >> >> Since you are still not a commuter I hope these contributions will help >> you be a committer to Siddhi as well :) >> I'll make this as a formal idea, do work on a proposal as well. >> >> Regards >> Suho >> >> >> On Wed, Mar 15, 2017 at 6:09 PM, Gobinath <slgobin...@gmail.com> wrote: >> >>> Hi team, >>> >>> This is Gobinath a former software engineer at WSO2 currently doing >>> masters at Western University. This time I plan to do GSoC with WSO2 and >>> this is the basic idea of what I have discussed with Suho. >>> Based on Suho's suggestion, I come up with a proposal to implement >>> detecting non-occurring events using Siddhi patterns. The current Siddhi >>> patterns allow identifying the patterns that present. >>> >>> See an example: >>> from every e1=Stream1[price>20] -> e2=Stream2[price>e1.price] within 1 >>> sec >>> select e1.symbol as symbol1, e2.symbol as symbol2 >>> insert into OutputStream; >>> >>> Detecting the absence of a pattern is not natively supported by Siddhi >>> patterns for the moment. In other words, identifying event_a not followed >>> by event_b within 2 minutes is not possible using the current patterns >>> implementation (Note that a time frame is required otherwise we have to >>> wait for infinite time to say event_b has not arrived). The current >>> workaround [1] to detect non-delivered items is shown below: >>> >>> from arrivals_stream#window.time(2 minutes) >>> select * >>> insert expired events into overdue_deliveries_stream; >>> >>> from every arrivalEvent = arrivals_stream -> >>> deliveryEvent = deliveries_stream[arrivalEvent.trackingId == trackingId] >>> or overdue_delivery = overdue_deliveries_stream[arrivalEvent.trackingId >>> == trackingId] >>> select arrivalEvent.trackingId as trackingId, arrivalEvent.customerName >>> as customerName, arrivalEvent.telephoneNo as telephoneNo, >>> deliveryEvent.trackingId as deliveryId >>> insert into filter_stream; >>> >>> from filter_stream [ (deliveryId is null)] >>> select trackingId, customerName, telephoneNo >>> insert into alert_stream; >>> >>> This solution requires a time window and it is inefficient if we are >>> interested only on one occurrence of such a pattern (In other words same >>> query without every keyword). Further, the query is more complex and not >>> user-friendly. >>> >>> If we provide patterns to detect absence of patterns, the above query >>> can be rewritten as below: >>> >>> from every arrivalEvent = arrivals_stream -> (not >>> deliveries_stream[arrivalEvent.trackingId == trackingId] within 2 min ) >>> select arrivalEvent.trackingId as trackingId, arrivalEvent.customerName >>> as customerName, arrivalEvent.telephoneNo as telephoneNo >>> insert into alert_stream; >>> >>> As you can see, we can use the existing language components like not & >>> within. This can be achieved by extending the existing >>> StreamPreStateProcessors and StreamPostStateProcessors with an internal >>> timer so that they can expire their internal list of events based on the >>> time limit. It is somewhat similar to time windows but the processor can >>> turn off the timer and ignore the events if it is a one time pattern >>> detection. >>> >>> I hope it gives the basic idea and I am waiting for your suggestions and >>> feedback. >>> >>> [1] https://docs.wso2.com/display/CEP400/Sample+0111+-+Detec >>> ting+non-occurrences+with+Patterns >>> >>> >>> Thanks & Regards, >>> Gobinath >>> -- >>> *Gobinath** Loganathan* >>> Graduate Student, >>> Electrical and Computer Engineering, >>> Western University. >>> Email : slgobin...@gmail.com >>> Mobile : (+1) 416-895-0721 >>> Blog : javahelps.com <http://www.javahelps.com/> >>> >>> >> >> >> >> -- >> >> *S. Suhothayan* >> Associate Director / Architect & Team Lead of WSO2 Complex Event >> Processor >> *WSO2 Inc. *http://wso2.com >> * <http://wso2.com/>* >> lean . enterprise . middleware >> >> >> *cell: (+94) 779 756 757 <077%20975%206757> | blog: >> http://suhothayan.blogspot.com/ <http://suhothayan.blogspot.com/>twitter: >> http://twitter.com/suhothayan <http://twitter.com/suhothayan> | linked-in: >> http://lk.linkedin.com/in/suhothayan <http://lk.linkedin.com/in/suhothayan>* >> > > > > -- > *Gobinath** Loganathan* > Graduate Student, > Electrical and Computer Engineering, > Western University. > Email : slgobin...@gmail.com > Mobile : (+1) 416-895-0721 > Blog : javahelps.com <http://www.javahelps.com/> > > -- *S. Suhothayan* Associate Director / Architect *WSO2 Inc. *http://wso2.com * <http://wso2.com/>* lean . enterprise . middleware *cell: (+94) 779 756 757 | blog: http://suhothayan.blogspot.com/ <http://suhothayan.blogspot.com/>twitter: http://twitter.com/suhothayan <http://twitter.com/suhothayan> | linked-in: http://lk.linkedin.com/in/suhothayan <http://lk.linkedin.com/in/suhothayan>*
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