A URL shortener service in 45 lines of Scala

skrebbel | karma 32746 | avg karma 5.58 · 2014-08-21 13:54:31

Now that Twitter auto-shortens URLs (and expands them in the UI), is there really a use left for URL-shorteners? Are there any other major platforms where text length matters?

austenallred | karma 22490 | avg karma 7.52 · 2014-08-21 14:01:19

The biggest advantage of URL shorteners, outside of the length, is the ability to quickly generate URLs that are track-able, instead of constantly adding campaigns with something like grasswire.com/1234?refid=twitter, which is how a lot of marketers track where their clicks come from.

rplnt | karma 6199 | avg karma 2.64 · 2014-08-21 14:51:40+00:00

This is only beneficial to one side of the userbase. For users clicking the links it's only inconvenience.

JazCE | karma 362 | avg karma 2.72 · 2014-08-21 14:16:25+00:00

Length matters when it comes to print format.

skrebbel | karma 32746 | avg karma 5.58 · 2014-08-21 14:39:14

but george-harrison-has-an-opinion is a lot easier to type without mistakes than An6X9z16Q.

and really it both sucks, which is why many print magazines collect an edition's links on a special page like magazinename.com/2014/5.

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JazCE | karma 362 | avg karma 2.72 · 2014-08-21 14:55:53+00:00

Yeah, they shouldn't be doing it like that. they should have control of their own shortener.

ff7c11 | karma 270 | avg karma 4.22 · 2014-08-21 15:04:03+00:00

In print: I like how net magazine uses netm.ag/description-123 for any links so it's easy to type and doesn't take up too much space. This also gives analytics for print articles where you normally can't watch whether anyone followed a link

You don't need to rely on routing through Twitter. Works when Twitter blocked or down. Branding.

Also tracking.

Also you can modify where the link points after distributing it in case you notice a mistake.

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agscala | karma 807 | avg karma 2.46 · 2014-08-21 14:03:09+00:00

Where does this handle getting the same random shortened url twice?

xwowsersx | karma 4033 | avg karma 2.48 · 2014-08-21 14:24:30+00:00

Good catch - it doesn't. We'd need to add a line to check for collision and retry. Better yet is to use hashing instead of random string as some folks mentioned in the comments on the blog.

tshadwell | karma 798 | avg karma 4.34 · 2014-08-21 14:08:11+00:00

As far as I am aware, the standard implementation of a URL shortening algorithm is to convert the number to a higher base, not to generate a random string. This has the advantages of greater loading speed, and smaller storage size.

Here is one I wrote long enough ago for me to be divorced from its implementation flaws: https://github.com/TShadwell/go-shorten/blob/master/shorten/...

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xwowsersx | karma 4033 | avg karma 2.48 · 2014-08-21 14:25:43+00:00

That makes sense. Thanks for the code.

stevewilhelm | karma 4837 | avg karma 4.57 · 2014-08-21 15:02:01+00:00

Instead of working on a URL shortner, I suggest you work on not sending usernames and passwords in clear text via HTTP POSTs.

eliotfowler | karma 11 | avg karma 1.0 · 2014-08-21 15:31:29

The site is blocked at my work so I can't see the implemtation but here is one I wrote back in march that is 79 lines: https://gist.github.com/eliotfowler/9360895

innguest | karma 112 | avg karma 0.14 · 2014-08-21 15:35:05+00:00

And another one I found, in 81 lines of Haskell (may be interesting for comparison): https://github.com/ryantrinkle/memoise/blob/master/src/Main....

There's also a presentation to go with it: http://vimeo.com/59109358

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TeeWEE | karma 1342 | avg karma 1.99 · 2014-08-21 16:03:14+00:00

I know scala is very powerful, but I think this code proofs to me that scala code is difficult to read. I'm a pro functional programmer, but scala mixes too many concepts.

'pseudo' Python url shorterner in 14 lines of code:

  from webapp2 import RequestHandler
  import redis

  def shorten_url(url):
    import base64
    return base64.encode(url)[:7]
  
  class Handler(RequestHandler):

    def get(self, path):
        self.redirect(redis.get(path))

    def post(self, path):
        redis.put(path, shorten_url(path))

GregorStocks | karma 151 | avg karma 2.13 · 2014-08-21 16:25:43+00:00

I believe you'll have a lot of collisions that way, as two URLs with the same 7-byte suffix in base64 will have the same key. The Scala version uses 7 random characters, which I think will lead to a collision after about sqrt(36^7) entries due to the birthday paradox (62^7 if alphanumeric includes both uppercase and lowercase). That's better, but I'd recommend just using something autoincrementing instead, which in theory makes collisions impossible.

TeeWEE | karma 1342 | avg karma 1.99 · 2014-08-21 16:32:01+00:00

I agree. It was a short pseudo implementation.

markc | karma 675 | avg karma 2.69 · 2014-08-21 16:11:48+00:00

Here's another one in 27 lines of Clojure: http://beauhinks.com/simple-url-shortener-with-clojure/

didip | karma 2495 | avg karma 2.56 · 2014-08-21 16:19:42+00:00

83 lines in Go: https://github.com/didip/shawty

u124556 | karma 89 | avg karma 0.78 · 2014-08-21 16:32:02+00:00

What would be the minimum path size in the shortened url to ensure a large enough capability of storage without letting users guess other urls easily?