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.

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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();
      });
    });
}

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();
  }
}

Here's a video demonstrating the first example:

Hope this was insightful.

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Quick links

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