rust ntex server

Cargo.toml:

[package]
name = "demo"
version = "0.1.0"
edition = "2021"

[dependencies]
serde = { version = "1.0.204", features = ["derive"] }
ntex = { version = "2.0.3", features = ["tokio"] }

main.rs:

use ntex::web;
use serde::Serialize;

#[derive(Serialize)]
struct Measurement {
    temperature: f32,
}

#[web::get("/")]
async fn index() -> impl web::Responder {
    // web::HttpResponse::Ok().body("Hello index!")
    "Hello index!"
}

#[web::post("/echo")]
async fn echo(req_body: String) -> impl web::Responder {
    // web::HttpResponse::Ok().body(req_body)
    req_body
}

#[web::get("/hello/{name}")]
async fn hello(name: web::types::Path<String>) -> impl web::Responder {
    format!("Hello {}!", &name)
}

async fn manual_hello() -> impl web::Responder {
    //  web::HttpResponse::Ok().body("Hey there!")
    "Hey there!"
}

#[web::get("/temp")]
async fn current_temperature() -> impl web::Responder {
    web::HttpResponse::Ok().json(&Measurement { temperature: 42.3 })
}

#[ntex::main]
async fn main() -> std::io::Result<()> {
    web::HttpServer::new(|| {
        web::App::new()
            .service(current_temperature)
            .service(echo)
            .service(hello)
            .service(index)
            .route("/hey", web::get().to(manual_hello))
    })
    .bind(("127.0.0.1", 8080))?
    .run()
    .await
}