Crate rflow

Expand description

RFlow

Chat-like HMI for embedded Rust applications and PLCs

RFlow is a part of RoboPLC project.

§The idea

Many of embedded applications and PLC programs do not have any human-machine interface and not supposed to have one by design.

However, sometimes it is very useful to have a simple way to interact with the application, e.g. for debugging purposes or having a basic emergency interface in production.

RFlow provides the most possible lightweight way to have a chat-like interface between the application (server) and its clients, which does not affect the application real-time run-flow and consumes minimal system resources.

The RFlow protocol is fully text-based and can be used with no special client.

MSRV: 1.68.0

§Clients

RFlow Chat - a dedicated RFlow chat client (terminal).
Custom clients, built with the crate Client API.
Any terminal TCP client, e.g. telnet, nc.

§A very basic example

use std::{thread, time::Duration};

use rtsc::time::interval;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let data_channel = rflow::take_data_channel()?;
    thread::spawn(move || {
        rflow::serve("127.0.0.1:4001").expect("failed to start server");
    });
    thread::spawn(move || {
        for _ in interval(Duration::from_secs(5)) {
            rflow::send("ping".to_string());
        }
    });
    for data in data_channel {
        println!("Received data: {}", data);
        rflow::send(format!("command accepted: {}", data));
        let command = data.trim();
        if command == "quit" {
            break;
        }
    }
    Ok(())
}

§Locking safety

Note: the asynchronous client uses parking_lot_rt locking only.

By default, the crate (both the server and the client modules) uses parking_lot for locking. For real-time applications, the following features are available:

locking-rt - use parking_lot_rt crate which is a spin-free fork of parking_lot.
locking-rt-safe - use rtsc priority-inheritance locking, which is not affected by priority inversion (Linux only).

Note: to switch locking policy, disable the crate default features.

§About