SiddhiQL模式和窗口查询

Question

I am trying to write a simple siddhi query which detects a pattern eg: "Ice" "cream" "x" "y" "apple" "water"

where events Ice & cream both should be together and apple water should be together and xy are any random values in the window.length(6)

problem is the following query is not restricting the window.length(6) how can i achieve this?

from every (( s1=windowedStream[s1.val=='ice']-> s2= windowedStream[s2.val=='cream'] )
            -> ( a1=windowedStream[a1.val=='apple'] -> a2 = windowedStream[a2.val =='water'] ))
select s1.meta_timestamp, s1.val
insert into filteredStream

Answer 1

As per the existent notations, Siddhi allows you to restrict a pattern based on a time window only. Please refer the following.

https://docs.wso2.com/display/CEP420/SiddhiQL+Guide+3.1#SiddhiQLGuide3.1-Pattern

As a workaround to restricting the patterns based on a length window, you may introduce a 3rd attribute called index to the "windowedStream", where index reflects the order of event arrival (ie index of the 1st event is 1, index of the 2nd event is 2 and so on). Then the following query would capture the patterns occurring within a length window of 6 events.

from every (( s1=tempStream[s1.val=='ice']-> s2= tempStream[s2.val=='cream'] )
        -> ( a1=tempStream[a1.val=='apple'] -> a2 = tempStream[a2.val =='water' and a2.index- s1.index <= 6]))
select s1.meta_timestamp, s1.val
insert into filteredStream;

Hope this helps.