Apache Stratos Event Aggregation/Summarization via a Complex Event Processor

[Nirmal Fernando <ni...@apache.org>]

Hi All,

With the new architecture, real-time events such as in-flight requests of a
load balancer, health of a Cartridge instance etc. would get published
directly to a Complex Event Processor (CEP). It's the duty of the CEP to
emit an aggregated version of the events it received, to the reliable
message broker so that auto-scaler could act upon the aggregated events.

So, what would be these aggregated events? Certainly it is not primitive as
in-flight requests count at a given time and also not to the extreme of
deciding whether to spawn a new instance, but some critical information,
lies in between. Some examples would be,


   - Average requests-in-flight count / load-average of an instance.
   - Gradient of requests-in-flight / load-average of an instance.
   - Second Derivative of requests-in-flight / load-average of an instance.
   (to detect whether the gradient is increasing or decreasing over a time
   period)
   - Summarize failed requests.
   - Pattern detection.

etc.

I will start a PoC with WSO2 CEP and share soon.

-- 
Best Regards,
Nirmal

Nirmal Fernando.
PPMC Member & Committer of Apache Stratos,
Senior Software Engineer, WSO2 Inc.

Blog: http://nirmalfdo.blogspot.com/