learnyounode/exercises/http_uppercaserer/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-uppercaserer.js`.

Write an HTTP **server** that receives only POST requests and converts incoming POST body characters to upper-case and returns it to the client.

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

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## HINTS

While you're not restricted to using the streaming capabilities of the `request` and `response` objects, it will be much easier if you do.

There are a number of different packages in npm that you can use to *"transform"* stream data as it's passing through. For this exercise the `through2-map` package offers the simplest API.

`through2-map` allows you to create a *transform stream* using only a single function that takes a chunk of data and returns a chunk of data. It's designed to work much like `Array#map()` but for streams:

```js
const map = require('through2-map')
inStream.pipe(map(function (chunk) {
  return chunk.toString().split('').reverse().join('')
})).pipe(outStream)
```

In the above example, the incoming data from `inStream` is converted to a String (if it isn't already), the characters are reversed and the result is passed through to `outStream`. So we've made a chunk character reverser! Remember though that the chunk size is determined up-stream and you have little control over it for incoming data.

To install `through2-map` type:

```sh
$ npm install through2-map
```

If you don't have an Internet connection, simply make a `node_modules` directory and copy the entire directory for the module you want to use from inside the {appname} installation directory:

  {rootdir:/node_modules/through2-map}

Documentation for through2-map has been installed along with {appname} on your system and you can read them by pointing your browser here:

  {rootdir:/docs/through2-map.html}

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

```sh
$ {appname} verify http-uppercaserer.js
```