RPC used by GCS The role is GCS worker set up in each work nodes
subject to https://github.com/ReyRen/GCS
https://www.cnblogs.com/niuben/p/14212878.html
https://grpc.io/docs/protoc-installation/ https://grpc.io/docs/languages/go/quickstart/
protoc -I proto/ --go_out=./proto --go_opt=paths=source_relative --go-grpc_opt=require_unimplemented_servers=false --go-grpc_out=./proto --go-grpc_opt=paths=source_relative proto/helloworld.proto