> > @Frances Sources are not simple DoFns. They add additional > functionality, e.g. checkpointing, watermark generation, creating > splits. If we want sinks to be portable, we should think about a > dedicated interface. At least for the checkpointing. >
We might be mixing sources and sinks in this conversation. ;-) Sources definitely provide additional functionality as you mentioned. But at least currently, sinks don't provide any new primitive functionality. Are you suggestion there needs to be a checkpointing interface for sinks beyond DoFn's bundle finalization? (Note that the existing Write for batch is just a PTransform based around ParDo.)
