Async implementation of grpc

[soum...@gmail.com]

Here is what I am trying to do.Both are grpc server and client

Client Calls to the Server. Client is interested in a topic. 

Server sends a response to the Client that your request has been accepted. As soon as there is data on the topic you(Client) will be notified.

Every time server receives a data on the topic(how does the server receive the data on the topic is out of scope.), it is sent across the client.

Question 

1. I understand grpc is pretty sync . To me the above flow is async in nature from Client pov . Is the above flow possible with grpc?

2. I hear about Completion Queue . Is completion queue a mechanism by which this problem can be solved? I fail to find completion queue implementation/example  in JAVA, Golang . Why are the examples so scarce?

Any help would be appreciated.

Thanks,

Deep