What order are events processed in iterative loop?

[John Tipper <jo...@hotmail.com>]

For the case of a single iteration of an iterative loop where the feedback type is different to the input stream type, what order are events processed in the forward flow? So for example, if we have:

  *   the input stream contains input1 followed by input2
  *   a ConnectedIterativeStream<input, feedback> at the head of an iteration
  *   followed by a CoProcessFunction, which emits a feedback element in response to an inputthat closes the ConnectedIterativeStream

For an input stream of input1 followed by input2, what order of events does the CoProcessFunction see?

Does it see "input1, feedback1, input2, feedback2", or "input1, input2, feedback1, feedback2", or is it a non-deterministic processing time order based on the execution time of the CoProcessFunction, but where input1 is always processed before input2 and feedback1 is always processed before feedback2, e.g. either of the two orders are possible?

Many thanks,

John