Quick Tip: Write an HTTP server in Dart

In today’s quick tip, we will explore one of the inbuilt classes Dart gives us for creating web servers. This class comes as part of the “dart:io” library in the SDK.

The class in particular is appropriately named HttpServer. Here’s how we’ll use it:

HttpServer.bind("localhost", 8080).then((HttpServer server) { ... });

bind() represents a static method that takes as required arguments a hostname and a port. This returns a Future<HttpServer>, allowing us to chain on methods like then() and catch().

A successfully bound hostname and port now allows us to receive incoming requests by calling the listen() method on the server object, which has a Streaming interface:

// ...
server.listen((HttpRequest request) {
  request.response.write('Hello world');
  request.response.close();
});

Receiving the request allows us to write out our response and end it. Here’s the full snippet in its glory:

import 'dart:io';

void main() {
  HttpServer
    .bind("localhost", 8080)
    .then((HttpServer server) {
      server.listen((HttpRequest request) {
        request.response.write("Hello world!");
        request.response.close();
      });
    });
}

Here’s a video demonstrating the first example:

Using Async/Await 🔥

Here’s a prettier way of writing a basic server:

import 'dart:io';

main() async {
  var server = await HttpServer.bind("localhost", 8080);

  await for (var request in server) {
    request.response.write("Hello world");
    request.response.close();
  }
}

Hope this was insightful.

Like, share and follow me 😍 for more content on Dart.

Quick links

1. HttpServer class
2. Free Dart screencasts on Egghead.io