# Clocker

## Sequence diagram

```plantuml
@startuml
participant FE as "Frontend" << React >>
participant Funnel as "Funnel" << Python >>
participant Segments as "ServeSegments" << Go >>
participant CurrentTime as "ServeCurrentTime" << NodeJS >>

activate FE #hotpink
    FE -> FE: Load page
    FE -> Funnel: WS Connect

    loop #ivory
        activate Funnel #gold
            Funnel -> Segments: GetHours()
            activate Segments #skyblue
            Segments -> CurrentTime: GetCurrentTime()
            activate CurrentTime #sandybrown
            return HH:MM:SS.ms
            return HH

            Funnel -> Segments: GetMinutes()
            activate Segments #skyblue
            Segments -> CurrentTime: GetCurrentTime()
            activate CurrentTime #sandybrown
            return HH:MM:SS.ms
            return MM

            Funnel -> Segments: GetSeconds()
            activate Segments #skyblue
            Segments -> CurrentTime: GetCurrentTime()
            activate CurrentTime #sandybrown
            return HH:MM:SS.ms
            return SS

            Funnel -> Segments: GetMilliseconds()
            activate Segments #skyblue
            Segments -> CurrentTime: GetCurrentTime()
            activate CurrentTime #sandybrown
            return HH:MM:SS.ms
            return ms

            Funnel -> FE: WS: Send formatted time
        deactivate Funnel
    end
deactivate FE

@enduml
```

## Services

| Service | Language | Port |
| -- | -- | -- |
| Funnel | Python | - |
| ServeCurrentTime | NodeJS | 50000 |
| ServeSegments | Go | 50001 |

### Funnel

Requirements:
- python 3.8+
- grpcio
- grpcio-tools

Install virtualenv and libs
```sh
cd src/funnel
virtualenv env
source env/bin/activate
pip install -r requirements.txt
```

Compile proto stubs:
```sh
cd src/funnel
make proto
```

Run service:
```sh
cd src/funnel
make run
```

### Go services

[gRPC Source](https://github.com/grpc/grpc-go)

Install protobuf compiler
```sh
go install google.golang.org/protobuf/cmd/protoc-gen-go@v1.28
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@v1.2
```

### Rust services

Update `rustc`

```sh
rustup update
```

#### [Tonic](https://github.com/hyperium/tonic)

Tonic is a gRPC over HTTP/2 implementation focused on high performance, interoperability, and flexibility. This library was created to have first class support of async/await and to act as a core building block for production systems written in Rust.

[Hello world tutorial](https://github.com/hyperium/tonic/blob/master/examples/helloworld-tutorial.md)


[Rust and gRPC: A complete guide](https://blog.logrocket.com/rust-and-grpc-a-complete-guide/)