Simple Rust gRPC demo

Shows client -> user-based processor -> subscription stream way.

Run server with

cargo run --bin server

Run client with

cargo run --bin client

Also, may use grpcc like this:

grpcc -i -p ./src/protos/example/service.proto --address 127.0.0.1:9000 --eval 'client.execute({command_id: 1}, printReply)'

TODO

[ ] Correct client unsubscription [ ] Sometimes server does not answer, fix that [ ] Use headers for user_id