How to implement a WindowableTask(similar to samza) in Apache flink?

[Debraj Manna]

I am new to flink and this is my first post in the community.


Samza has a concept of windowing
<https://samza.incubator.apache.org/learn/documentation/0.7.0/container/windowing.html>
where
a stream processing job needs to do something in regular intervals,
regardless of how many incoming messages the job is processing.

For example, a simple per-minute event counter in samza will be like below:


public class EventCounterTask implements StreamTask, WindowableTask {

  public static final SystemStream OUTPUT_STREAM =
    new SystemStream("kafka", "events-per-minute");

  private int eventsSeen = 0;

  public void process(IncomingMessageEnvelope envelope,
                      MessageCollector collector,
                      TaskCoordinator coordinator) {
    eventsSeen++;
  }

  public void window(MessageCollector collector,
                     TaskCoordinator coordinator) {
    collector.send(new OutgoingMessageEnvelope(OUTPUT_STREAM, eventsSeen));
    eventsSeen = 0;
  }
}

Can someone let me know how to implement an equivalent thing in apache
flink (samza is single threaded so window and process will not happen
concurrently) or point me to the relevant documentation?