When the docs and learn-onyx say that exceptions cannot be serialized, do you mean that onyx won't serialize them because they are not maps, right? Because technically I believe they are serializable.

@yonatanel: yeah, it's partially because you should send them on in maps, it's also partially because it's a little old and nippy can serialise exceptions and send them on now. That said, it's pretty easy for Clojure ex-infos to contain non serializable objects, which is why the the point was originally included in the docs. We should probably revise it to say

Why does :onyx/uniqueness-key belong in the catalog task definition and not the window definition?

The filtering mechanisms happens at the segment level, agnostic to any windows. That parameter will go away in the next major release, the ABS streaming engine can infer duplicates without the user telling it what key to look at.

Excited to see the new ABS version!

I believe there's a mistake in the user guide, using a :global window together with :window/range, and it also contradicts the doc string which mentions "fixed windows": http://www.onyxplatform.org/docs/user-guide/0.9.11/#state-example

Is it possible to emit segments from aggregations downstream, or do I have to emit them directly to Kafka for example and have some input task read from that?

From Kafka. I think it will possible in the future