Will there ever be a

CoBroadcastProcessFunction

and

KeyedCoBroadcastProcessFunction

?

Never say never but I haven’t seen such plans. What’s your use case?

I have two streams that normally would work well with the

KeyedCoProcessFunction

. Stream A is some rule information and stream B is the data the rule should be evaluated over. However, the timestamp information that flows in over stream B isn't the full picture so I wanted to attach a third stream of information that includes all the observed timestamps from the devices that make up stream B instead of just the limited amount of timestamp info that trickles in. I didn't want a global watermark strategy since there's no way to generate watermarks per source. I was originally going with the broadcast pattern for the time and let the process function downselect what it actually needed. I think that's fine for few devices but likely has issues as throughput goes up with more devices added. Without a broadcast pattern, I'll have to create a stream of timestamp information, duplicate the messages as needed and add a key so that it can be joined by union with stream B.

I think the community is more looking into https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=195730308