An HTTP server accepts requests and returns HTTP responses. A small Rust server makes the request path visible: it listens for TCP byte streams, converts them into HTTP requests, routes each request to a handler, and sends the handler’s response back as bytes. This division keeps listening, message conversion, routing, and response construction separate. section 2.3
A from-scratch implementation can be assembled in this order:
- Build an HTTP library with HttpRequest and HttpResponse types to convert between messages and Rust data structures. section 2.3
- Add the main function and server module to receive TCP streams; add a router to select handlers and handlers to construct responses. section 2.3
- Handle GET requests for static pages and JSON data. This demonstrates both static web serving and a limited web-service capability, not a production-ready HTTP server. section 2.0 section 2.3.5
With Actix, the framework supplies the HTTP server. Configure a path and method with a handler, register that route in an App, then construct and run HttpServer. An Actix server uses worker threads and creates an application instance for each OS thread; the app groups the routes it can handle. section 3.1.1 section 3.1.2
Listing 3.1 Writing a basic Actix web server
// Module imports
use actix_web::{web, App, HttpResponse, HttpServer, Responder};
use std::io;
// Configure route #1
pub fn general_routes(cfg: &mut web::ServiceConfig) {
cfg.route("/health", web::get().to(health_check_handler));
}
//Configure handler #2
pub async fn health_check_handler() -> impl Responder {
HttpResponse::Ok().json("Hello. EzyTutors is alive and kicking")
}
// Instantiate and run the HTTP server
#[actix_rt::main]
async fn main() -> io::Result<()> {
// Construct app and configure routes #3
let app = move || App::new().configure(general_routes);
// Start HTTP server #4
HttpServer::new(app).bind("127.0.0.1:3000")?.run().await
}
The runnable Actix example places the four steps together in src/bin/basic-server.rs: /health routes GET requests to an async handler, and HttpServer binds to 127.0.0.1:3000. section 3.1.1
Check the response, not just the page
Run the from-scratch server and request /, /health, /api/shipping/orders, and /invalid-path with a browser or curl. The index page causes the browser to fetch styles.css separately. Browser developer tools show text/html for HTML, text/css for CSS, and application/json for the orders response. section 2.3.5
A server’s role can change within an application. For a sign-in form, a frontend Actix server receives a POST on the sign-in route; its handler checks credentials in a local database, then redisplays the form with an error or directs the authenticated user to the home page. That frontend server is distinct from the backend web service. section 9.1
