Disclaimer: I am one of the Flink committers.

While Flink has in fact no direct SQL entry point right now (and many users simply wrap the API entry points themselves to form a SQL entry point), the other statements are actually not quite right.

  - Flink as a whole (and SQL sits just on the DataStream API) works local, distributed and embedded as well.

  - Flink does not have any external dependencies, not even Kafka/ZooKeeper; it is self-contained. One can even just receive a data stream via a socket if that works for the use case.

  - Flink itself has always had exactly-once semantics, and works also exactly-once with Kafka.