Some people here (especially Flink contributors) might be interested to know about this project: https://reef.apache.org/index.html
It is lower-level than Flink (and less mature), but with similar architectural sensibilities and emphasis on interfaces. It would be pretty interesting to compare the designs in areas of overlap, and maybe some cross-pollination of ideas (if not outright reuse/compatibility) is possible. Also check out the related subprojects: https://reef.apache.org/tang.html https://reef.apache.org/wake.html
