grpc-python-server-push-example

WARNING! I do not know if this is the correct way to implement server push.

1. Construct a stream-stream connection.

2. In client-side, pass the id of client via metadata. The stub should return an iterator, and call next() method of this method will block cause server has not responsed yet.

3. In server-side, when it receives the first request, construct a new Queue. Then, blocking reading this queue by Queue.get(). Once some new data is written into this queue, server will raise a response to client. In this example, writter is a standard input which is invoked in another thread.