Dear Community, I have three questions regarding Joins in Apache Storm. For those, I`d like to use the Stream API.
The documentation provides an example where a windowed stream A is joined with a non-windowed stream B. So I assume that the window is built on stream A and all tuples from B that are arriving within the window time are then joined with the ones from A. 1. However, I found that it is possible to join two non-windowed streams as well and in a small demo set-up, I receive results as well. But how can it be? Without a window, the tuples from A and B would have to arrive at the exact same timestamp in order to get joined. Or am I wrong here? 2. Is the output of a join of a windowed and a non-windowed stream again a windowed stream? I would assume that since I would expect groups of joined tuples. 3. What is the right way to join three streams? I think, that one window configuration is enough. So the pseudocode would look like: streamC.join(streamB.join(windowedstreamA). However, this raises a punctuation error. Looking forward for your responses, Best regards, Roman
