Materialize connects directly to event stream processors (like Kafka) --- how about Pulsar? (Goggling doesn't yield anything useful, Materialize and Pulsar are both name of brands of other things)
[0] https://pulsar.apache.org/docs/en/adaptors-kafka/
EDIT: I don't think this adaptor will work after all, it works by replacing the Kafka Java client library with its own, so is only applicable to Java applications.
* timestamped changes eg "record foo was deleted at time 42"
* watermarks eg "I've now sent you all the changes up to time 42"
Here's the implementation of the kafka source - https://github.com/MaterializeInc/materialize/blob/master/sr.... (There's also a bit of code in the parser/planner to wire up the CREATE SOURCE syntax, but it's fairly trivial.)