Explore messaging in Rust.
grpcurl -plaintext -import-path ./proto -proto broker.proto -d "{ \"message\": \"tim $(date)\"}" [::]:50051 broker.Broker/Publish
grpcurl -plaintext -import-path ./proto -proto broker.proto [::]:50051 broker.Broker/Subscribe
grpcurl -vv -plaintext -import-path ./proto -proto broker.proto [::]:50051 broker.Broker/Subscribe