In Esper CEP engine event patterns, there's Every operator which indicates that the pattern sub-expression should restart when the sub-expression qualified by the every keyword evaluates to true or false.
According to this document, We can use every operator in different ways like:
A -> B
every ( A -> B )
every A -> B
A -> every B
every A -> every B
I would like to know which of these patterns are possible in Flink CEP? I want to use every A -> B in Flink but don't know how.
And which one of the above patterns this default CEP pattern in Flink represents? (Using Flink v1.1.4)
Pattern<Event, ?> pattern = Pattern.begin("start").where(evt -> evt.getId() == 42)
.followedBy("end").where(evt -> evt.getName().equals("end"));
Thanks in advance.
Flink provides some documentation as to how to use every which says that if you specify subtype then it will be called for every iteration
start.subtype(SubEvent.class).where(new SimpleCondition<SubEvent>() {
@Override
public boolean filter(SubEvent value) {
return ... // some condition
}
});
But in my opinion, it is not what you are looking for. However, you can have a look at a light-weight Siddhi- Flink CEP library by using which you will be able to use siddhi query language in Flink
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