learnyounode/exercises/http_file_server/problem.md

Learn You The Node.js For Much Win! An intro to Node.js via a set of self-guided workshops.

Create a file named `http-file-server.js`.

Write an HTTP **server** that serves the same text file for each request it receives.

Your server should listen on the port provided by the first argument to your program.

You will be provided with the location of the file to serve as the second command-line argument. You **must** use the `fs.createReadStream()` method to stream the file contents to the response.

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## HINTS

Because we need to create an HTTP server for this exercise rather than a generic TCP server, we should use the `http` module from Node core. Like the `net` module, `http` also has a method named `http.createServer()` but this one creates a server that can talk HTTP.

`http.createServer()` takes a callback that is called once for each connection received by your server. The callback function has the signature:

```js
function callback (request, response) { /* ... */ }
```

Where the two arguments are objects representing the HTTP request and the corresponding response for this request. `request` is used to fetch properties, such as the header and query-string from the request while `response` is for sending data to the client, both headers and body.

Both `request` and `response` are also Node streams! Which means that you can use the streaming abstractions to send and receive data if they suit your use-case.

`http.createServer()` also returns an instance of your `server`. You must call `server.listen(portNumber)` to start listening on a particular port.

A typical Node HTTP server looks like this:

```js
const http = require('http')
const server = http.createServer(function (req, res) {
  // request handling logic...
})
server.listen(8000)
```

Documentation on the `http` module can be found by pointing your browser here:
  {rootdir:/docs-nodejs/http.html}

The `fs` core module also has some streaming APIs for files. You will need to use the `fs.createReadStream()` method to create a stream representing the file you are given as a command-line argument. The method returns a stream object which you can use `src.pipe(dst)` to pipe the data from the `src` stream to the `dst` stream. In this way you can connect a filesystem stream with an HTTP response stream.

Check to see if your program is correct by running this command:

```sh
$ {appname} verify http-file-server.js
```