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From Sameer W <sam...@axiomine.com>
Subject Re: What is the best way to load/add patterns dynamically (at runtime) with Flink?
Date Tue, 11 Oct 2016 21:23:11 GMT
I have used a JavaScript engine in my CEP to evaluate my patterns. Each
event is a list of named attributes (HashMap like). And event is attached
to a list of rules expressed as JavaScript code (See example below with one
rule but I can match as many rules).  The rules are distributed over a
connected stream which allow it to change over time. This is how I do it to
keep my rules dynamic. If someone has a better way I would love to hear it
as well.

private transient ScriptEngineManager factory = new ScriptEngineManager();
private transient ScriptEngine engine =
/*Inside open*/
factory = new ScriptEngineManager();

/*Close open*/

/*Inside my operator*/
engine = factory.getEngineByName("JavaScript");
engine.put("evt", value.f1); //value.f1 contains a JSON version of my
HashMap of attributes
engine.eval(value.f2.rule); //f2.last contains the rule which is evaluated
by the JavaScript Engine
Sample JavaScript contained in the call - engine.eval(value.f2.rule); is
shown below (not the "evt" variable in the JavaScript and the the preceding
line - engine.put("evt", value.f1);

*var evt=JSON.parse(evt);var result = evt.temperature>50 &&
boolean ret = (boolean)engine.get("result");

if(ret) /*Rule is Matched*/

> On Oct 11, 2016, at 5:01 PM, PedroMrChaves <pedro.mr.chaves@gmail.com>
> Hello,
> I am new to Apache Flink and am trying to build a CEP using Flink's API.
> of the requirements is the ability to add/change patterns at runtime for
> anomaly detection (maintaining the systems availability). Any Ideas of how
> could I do that?
> For instance, If I have a stream of security events (accesses,
> authentications ,etc.) and a pattern for detecting anomalies I would like
> be able to change that pattern parameters, for instance instead of
> the occurrence of events A->B->C I would like to change the condition on B
> to B’ in order to have a new rule. Moreover, I would like to be able to
> create new patterns dynamically as new use cases arise.
> Best Regards,
> Pedro Chaves
> --
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