《Elixir 101》快速架設 HTTP 伺服器

在 NodeJS 架設 HTTP 伺服器

const http = require('http');
​
function serverHandler(req, res){
  switch (req.url){
    case '/':{
      res.writeHead(200, {'Content-Type':'text/html'});
      res.write('Hello world');
      res.end();
      break;
    }
      
    default:{
      res.writeHead(404, {'Content-Type':'text/html'});
      res.end('Not found');
      break;
    }
  }
}
​
const server = http.createServer(serverHandler);
server.listen(3001);

const server = require('express')();
​
server.get('/', function (req, res) {
  res.send('Hello World')
});
​
server.listen(3000);

在 Elixir 中架設伺服器

$ mix new http_server --sup

.
├── README.md
├── lib
│   ├── http_server
│   │   └── application.ex
│   └── http_server.ex
├── mix.exs
└── test
    ├── http_server_test.exs
    └── test_helper.exs

安裝 plug

defmodule HttpServer.MixProject do
  use Mix.Project
​
  def project do
    [
      app: :http_server,
      version: "0.1.0",
      elixir: "~> 1.9",
      start_permanent: Mix.env() == :prod,
      deps: deps()
    ]
  end
​
  # Run "mix help compile.app" to learn about applications.
  def application do
    [
      extra_applications: [:logger],
      mod: {HttpServer.Application, []}
    ]
  end
​
  # Run "mix help deps" to learn about dependencies.
  defp deps do
    [
      # {:dep_from_hexpm, "~> 0.3.0"},
      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
    ]
  end
end

# Run "mix help deps" to learn about dependencies.
defp deps do
  [
    # {:dep_from_hexpm, "~> 0.3.0"},
    # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
  ]
end

# Run "mix help deps" to learn about dependencies.
defp deps do
  [
    {:plug_cowboy, "~> 2.0"}
  ]
end

首頁顯示 Hello World

defmodule Router do
  import Plug.Conn
​
  def init(options) do
    options
  end
​
  def call(conn, _opts) do
    conn
    |> put_resp_content_type("text/plain")
    |> send_resp(200, "Hello world")
  end
end

讓伺服器隨同程式上線

defmodule HttpServer.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false
​
  use Application
​
  def start(_type, _args) do
    children = [
      # Starts a worker by calling: HttpServer.Worker.start_link(arg)
      # {HttpServer.Worker, arg}
    ]
​
    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: HttpServer.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

{Plug.Cowboy, scheme: :http, plug: Router, options: [port: 4001]}

children = [
  {Plug.Cowboy, scheme: :http, plug: Router, options: [port: 4001]}
]

執行程式

$ mix run --no-halt

$ cd http_server

• https://github.com/elixir-plug/plug
• https://elixirschool.com/zh-hant/lessons/specifics/plug/