Structured Streaming : Custom Source and Sink Development and PySpark.

[Ramaswamy, Muthuraman]

I would like to develop Custom Source and Sink. So, I have a couple of 
questions:


  1.  Do I have to use Scala or Java to develop these Custom Source/Sink?


  1.  Also, once the source/sink has been developed, to use in PySpark/Python, 
do I have to develop any Py4J modules? Any pointers or good documentation or 
GitHub Source as a reference will be of great help.

Please advise.

Thank you,