Hi all, So let's say I have 2 topics coming that I want to join using KStream#join. I set them up like so:
KStreamBuilder builder = new KStreamBuilder(); KStream<String, String> a = builder.stream(TOPIC_A); KStream<String, String> b = builder.stream(TOPIC_B); a.join(b, (msgA, msgB) -> msgA + msgB, JoinWindows.of(TimeUnit.HOURS.inMillis(1)) .print(); So this works fine and joins the messages together. But what happens to messages that don't find a join partner in the other topic within the window? If I get a message in topic A and its partner doesn't occur in B, when and how does the message get consumed? Is there a way to write my application so that this is caught somehow and handled? I'm aware that I could use a leftJoin instead, but that would call the merge function twice, once with (msgA, null) and the second time with (msgA, msgB). I'm trying to find a solution that only calls one or the other. Is there a way to do this cleanly? Thanks! --Michael Thaler
