Last week, Digg announced the launch of the DiggBar which manages to combine two trends that Web geeks can't stand. It is both a URL shortener (whose problems are captured in the excellent post by Joshua Schachter on URL shorteners) and brings back the trend of one website putting another's content in a frame (which has detailed criticism in the wikipedia article on framing on the World Wide Web). 

The increasing popularity of URL shortening services has been fueled by the growth of Twitter. Twitter has a 140 character limit on posts on the site which means users sharing links on the site often have to find some way of shortening URLs to make their content fit within the limit. From my perspective, this is really a problem that Twitter should fix given the amount of collateral damage the growth of these services may end up placing on the Web.

Some Web developers believe this problem can be solved by the judicious use of microformats. One such developer is Chris Shiflett who has written a post entitled Save the Internet with rev="canonical" which states the following

There's a new proposal ("URL shortening that doesn't hurt the Internet") floating around for using rev="canonical" to help put a stop to the URL-shortening madness. It sounds like a pretty good idea, and based on some discussions on IRC this morning, I think a more thorough explanation would be helpful. I'm going to try.

This is easiest to explain with an example. I have an article about CSRF located at the following URL:

I happen to think this URL is beautiful. :-) Unfortunately, it is sure to get mangled into some garbage URL if you try to talk about it on Twitter, because it's not very short. I really hate when that happens. What can I do?

If rev="canonical" gains momentum and support, I can offer my own short URL for people who need one. Perhaps I decide the following is an acceptable alternative:

Here are some clear advantages this URL has over any replacement:

  • The URL is mine. If it goes away, it's my fault. (Ma.gnolia reminds us of the potential for data loss when relying on third parties.)
  • The URL has meaning. Both the domain ( and the path (csrf) are meaningful.
  • Because the URL has meaning, visitors who click the link know where they're going.
  • I can search for links to my content; they're not hidden behind an indefinite number of short URLs.

There are other advantages, but these are the few I can think of quickly.

Let's try to walk through how this is expected to work. I type in a long URL like into Twitter. Twitter allows me to post the URL and then crawls the site to see if it has a link tag with a rev="canonical" attribute. It finds one and then replaces the short URL with something like which is the alternate short URL I've created for my talk. What could go wrong? Smile

So for this to solve the problem, every site that could potentially be linked to from Twitter (i.e. every website in the world) needs to run their own URL shortening service. Then Twitter needs to make sure to crawl the website behind every URL in every tweet that flows through the system.  Oh yeah, and the fact is that the URLs still aren't as efficient as those created by sites like unless everyone buys a short domain name as well.

Sounds like a lot of stars have to align to make this useful to the general populace and not just a hack that is implemented by a couple dozen web geeks.  

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