Esper EPL Query for Time(t) and Time(t-1)

Question

I am trying to implement an EPL query that can pick up the avg for Time(t) & Time(t-1).

For example:

a) in the first 5 seconds (seconds 0-5) there are 2 events with an avg of 12

b) in the next 5 seconds (seconds 5-10) there are 3 events with an avg of 23 , and in the EPL query that catches this information, I am able to also see the avg of 12 from the previous time window of the first 5 seconds

The idea I have is to stagger the objects/queries in such a way that the final epl query has a snapshot of Time(t) & Time(t-1), as seen in the virtually created object ScoreInfoBeforeAfter . However it's not working.

Any ideas would be greatly appreciated. Thanks.

~~~~

// The object being published to the Esper stream:
class ScoreEvent { int score; ... }

Answer 1

Looks like the keyword prior is the solution.

http://esper.codehaus.org/esper-2.1.0/doc/reference/en/html/functionreference.html

See: Section 7.1.9

In terms of the example I described in the original post, here's the corresponding solution I found. It seems to be working correctly.

INSERT INTO ScoreInfo
SELECT 
    'ScoreInfo' as a_Label, 
    average AS curAvg, 
    prior(1, average) AS prevAvg 
FROM 
    ScoreEvent.win:time_batch(5 sec).stat:uni(score);


SELECT
*
FROM
ScoreInfo.win:length(1);

..
And then it's nice, because you can do stuff like this:

SELECT
    'GT curAvg > prevAvg' as a_Label, 
    curAvg, 
    prevAvg 
FROM
    ScoreInfo.win:length(1)
WHERE
    curAvg > prevAvg;


SELECT
    'LTE curAvg <= prevAvg' as a_Label, 
    curAvg, 
    prevAvg 
FROM
    ScoreInfo.win:length(1)
WHERE
    curAvg <= prevAvg;