rel-shortlink

Specification 2009-05-04

Editors

• Sam Johnston (Google)

Concept

• Sam Johnston (Australian Online Solutions)
• Chris Shiflett (OmniTI) rev=canonical
• Kellan Elliott-McCrae (Flickr) rev=canonical
• Robert Spychala (Snaplog) rel=shorturl

Copyright

Public Domain Contribution Requirement. Since the author(s) released this work into the public domain, in order to maintain this work's public domain status, all contributors to this page agree to release their contributions to this page to the public domain as well. Contributors may indicate their agreement by adding the public domain release template to their user page per the Voluntary Public Domain Declarations instructions. Unreleased contributions may be reverted/removed.

Patents

This specification is subject to a royalty free patent policy, e.g. per the W3C Patent Policy, and IETF RFC3667 & RFC3668.

Abstract

RelShortLink is a brainstorm proposal with the goal of becoming an elemental microformat.

The problem-space that rel-shortlink is attempting to solve is being taken through the microformats process, and this is the current brainstorm that seems to make more sense than the alternatives. Nonetheless, additional background documentation is needed at the following stub pages:

• shortlink-examples
• shortlink-formats
• shortlink-brainstorming

Proposed usage: by adding rel="shortlink" to a [hyper]link, a page indicates that the hyperlink may be used for space constrained and/or manual entry (e.g. printed or spoken) applications and that the destination of that hyperlink carries the same meaning (even if formatting such as sort order and hightlighting is lost). Typical use cases include pasting links into microblogging services such as Twitter and anywhere manual entry is required (e.g. printed or spoken URLs).

Additional variants: (these should probably be further documented on shortlink-brainstorming)

• Portion of a page such as a blog post. Taking the lesson learned from rel-license, which was subsequently applied to rel-tag, a portion of a page (such as a blog post) defined by a compound microformat (e.g. an "hentry" from hAtom) may also refer to a shortened URL for that portion of the page with the use of rel="shortlink".

• classname alternative. Pages (or portions thereof) that with to reference/publish a shortlink for themselves but without directly hyperlinking to the shortlink may do so by marking up the shortlink URL in an element with class name of "shortlink".

Examples

HTML

On a page like http://www.flickr.com/photos/tantek/3909804165/ it could have HTML to indicate a shortlink in one of two ways:

<link rel="shortlink" type="text/html" href="http://flic.kr/p/6XuLyD">

and/or

shortlink: 
<a rel="shortlink" type="text/html" href="http://flic.kr/p/6XuLyD">
 http://flic.kr/p/6XuLyD
</a>

HTTP

In addition, a request for a page like http://www.flickr.com/photos/tantek/3909804165/ should return as part of the HTTP headers:

Link: <http://flic.kr/p/6XuLyD>; rel="shortlink"

XMDP profile

<dl class="profile">
 <dt id="rel">rel</dt>
 <dd><p>
   <a rel="help" href="http://www.w3.org/TR/html401/struct/links.html#adef-rel">
     HTML4 definition of the 'rel' attribute.</a>  
   Here is an additional value.</p>
  <dl>
   <dt id="shortlink">shortlink</dt>
   <dd>Indicates that the referred resource carries the same meaning as the
       referring page (even if formatting such as sort order and highlighting
       is lost) and that the link may be used for space constrained and/or
       manual entry (e.g. printed or spoken) applications.</dd>
  </dl>
 </dd>
</dl>

examples in the wild

This section is informative and in alphabetical order.

Note: There are numerous uses of rel-shortlink in the wild, this is very much an incomplete list. If your site marked up with rel-shortlink, feel free to add it to the top of this list. Once the list grows too big, we'll make a separate wiki page (rel-shortlink-examples-in-wild).

• AlanHogan.com uses rel-shortlink in HTTP headers, HTML head, and the "shortlink" tag on input elements for high-traffic content pages.
• CMS Market uses it on each of their directory and news pages. They'll be releasing their tool as a GPL'd Joomla component at some point as well.
• Jordan Clark has shortened forms of URLs from several of the most common and popular link-shortening services, all of which point to the home-page of his website, www.jdclark.org.
• Lessn More, a free and open-source personal URL shortening service. Its website uses rel-shortlink in HTTP headers and HTML <head>, and the installable codebase uses the shortlink class on inputs for copy/paste.
• Media UK uses it on each of their directory pages, using their muk.fm shortening service.
• RelShortLink is an open source Python implementation hosted on Google App Engine which scans both HTTP headers and HTML links for rel=shortlink.
• tantek.com uses the class name variant of shortlink on all permalink pages, in particular on an input element for easy copy/pasting of the shortlink, e.g. http://tantek.com/2010/034/t2/diso-2-personal-domains-shortener-hatom-push-relmeauth
• TechCrunch advertises wp.me links in its HTTP headers.
• WordPress.com uses it on ~7 million blogs with their WP.me URL shortening service.
• Wordpress 'shortlink' plugin embeds rel=shortlink links into Wordpress blogs.
• Yedda.com (an AOL company), uses it on all question pages with their internal short URLs mechanism.

normative references

• XMDP
• shortlink Specification

informative references

• draft-nottingham-http-link-header
• Google Code 'shortlink' project
• Introducing rel="shortlink" - a better alternative to URL shorteners
• rel=shortlink: url shortening that really doesn't hurt the Internet
• rel="shortlink" proposal for advertising short URLs in HTML/HTTP thread on IETF apps-discuss

inferior alternatives

• RevCanonical
  • rev= deprecated in HTML 5
  • rev= is easily confused with rel=, thus creating extreme danger for clueless webmasters
  • implies that referring URL is the canonical URL, thus should only be used for the canonical URL itself
  • implies that a complete list of referring URLs is offered, when in fact there are infinite possibilities
  • See also mnot's Counting the ways that rev="canonical" hurts the Web
• RelShortcut
  • Scorched earth thanks to "shortcut icon" (now just "icon" in HTML 5) - rel is a space separated list for HTML at least
• RelShort[er]
  • Ambiguous as to whether it refers to the URL or the content itself (e.g. abstract).
• RelShorturl
  • Too many possible permutations: short[_- ]?ur[il] -> shorturl, short_url, short-url, "short url", short_uri, short-uri, "short uri", etc. leads to implementations supporting multiple variations.
  • Intellectual property issues:
    • Trademark status claimed by shorturl.com (shortlink infringes no known common law or registered trademarks)
    • Copyright protected specification (shortlink specification is public domain)
    • Patent status unknown (shortlink carries a patent pledge and has no known patents)
  • No effort to standardise via the usual processes (shortlink was submitted to IETF/W3C for discussion)