Shorty Challenge

The trendy modern question for developer inteviews seems to be, "how to create an url shortner". Not wanting to fall too far from the cool kids, we have a challenge for you!

The Challenge

The challenge, if you choose to accept it, is to create a micro service to shorten urls, in the style that TinyURL and bit.ly made popular.

Rules

1. The service must expose HTTP endpoints according to the definition below.
2. The service must be self contained, you can use any language and technology you like, but it must be possible to set it up from a fresh install of Ubuntu Server, by following the steps you write in the README.
3. It must be well tested, it must also be possible to run the entire test suit with a single command from the directory of your repository.
4. The service must be versioned using git and submitted by making a Pull Request against this repository, git history should be meaningful.
5. You don't have to use a datastore, you can have all data in memory, but we'd be more impressed if you do use one.

Tips

• Less is more, small is beautiful, you know the drill — stick to the requirements.
• Don't try to make the microservice play well with others, the system is all yours.
• No need to take care of domains, that's for a reverse proxy to handle.
• Unit tests > Integration tests, but be careful with untested parts of the system.

Good Luck! — not that you need any ;)

---

API Documentation

All responses must be encoded in JSON and have the appropriate Content-Type header

POST /shorten

POST /shorten
Content-Type: "application/json"

{
  "url": "http://example.com",
  "shortcode": "example"
}

Attribute	Description
url	url to shorten
shortcode	preferential shortcode

Returns:

201 Created
Content-Type: "application/json"

{
  "shortcode": :shortcode
}

A random shortcode is generated if none is requested, the generated short code has exactly 6 alpahnumeric characters and passes the following regexp: ^[0-9a-zA-Z_]{6}$.

Errors:

Error	Description
400	url is not present
409	The the desired shortcode is already in use. Shortcodes are case-sensitive.
422	The shortcode fails to meet the following regexp: ^[0-9a-zA-Z_]{4,}$.

GET /:shortcode

GET /:shortcode
Content-Type: "application/json"

Attribute	Description
shortcode	url encoded shortcode

Returns

302 response with the location header pointing to the shortened URL

HTTP/1.1 302 Found
Location: http://www.example.com

Errors

Error	Description
404	The shortcode cannot be found in the system

GET /:shortcode/stats

GET /:code
Content-Type: "application/json"

Attribute	Description
shortcode	url encoded shortcode

Returns

200 OK
Content-Type: "application/json"

{
  "startDate": "2012-04-23T18:25:43.511Z",
  "lastSeenDate": "2012-04-23T18:25:43.511Z",
  "redirectCount": 1
}

Attribute	Description
startDate	date when the url was encoded, conformant to ISO8601
redirectCount	number of times the endpoint GET /shortcode was called
lastSeenDate	date of the last time the a redirect was issued, not present if redirectCount == 0

Errors

Error	Description
404	The shortcode cannot be found in the system