Hey Milad, since you cannot look into the future which element comes next, you have to "lag" one behind. This requires building an operator that creates 2-tuples from incoming elements containing (current-1, current), so basically a single value state that emits the last and the current element in a tuple.
In a trigger, the element is then of the 2-tuple type and you can see changes "beforehand". The last element of 1's is then (1, 2). Hope this helps. -- View this message in context: http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/How-to-sessionize-stream-with-Apache-Flink-tp13817p13818.html Sent from the Apache Flink User Mailing List archive. mailing list archive at Nabble.com.
