RingCentral CX Call Streaming to gRPC server

I am trying to stream call from RingCentral CX using gRPC server. Found the following page: 

https://support.ringcentral.com/article-v2/using-streaming-nodes-in-ringcx-workflow-studio.html  

However, this page does not provide any detailed information regarding the gRPC server implementation. Here we only must provide server address with security credentials. I mainly have three questions: 

1. To implement gRPC server, clients need to know which server function to call. And I don’t see any scope where I can provide “. proto” file or configure the client streaming data through dedicated server function. How can I configure the call stream to find “.proto” schema? 

2. I found a detailed implementation using WebSocket Server (WSS) (https://developers.ringcentral.com/engage/voice/guide/workforce/call-streaming/getting-started ). Is there any such working demo which implements a gRPC server? 

3. Once we create a streaming workflow, is it applied to every call for every agent in the company? Or is it applied to a certain group like it’s specified in the UC documentation (https://developers.ringcentral.com/guide/voice/supervision#python)? It says you have to create monitoring groups, so you can only stream calls for agents in those monitoring groups. Do we have the same concept here? Any detailed documentation?