The operator ensures the order of tuples. It collects all tuples in input until a heartbeat-punctuation is received, then it writes all collected tuples to output in the correct order. So the ordered output contains all tuples which were received after the last received heartbeat-punctuation. There has to be an operator that send an HEARTBEAT before this operator.
Example
Assure Order Operator
ordered_output = REORDER(input)
Remark: Renamed from AssureOrder