Big-time app uses the a/@rel attribute, boosting folksonomy development

by Bob DuCharme

There's been a lot of buzz about so-called "folksonomies" lately—the use of taxonomies developed on the fly by user communities instead of by centralized developers who create a list of terms that users must choose from. Examples of the latter are used for my employer's databases of legal material and the O'Reilly Developer Network weblogs. (What do they do with those Secondary Subjects and Topics that we select when we enter these, anyway?) The most well-known examples of the former are the tags that users can add to flickr photos and the keywords that can be added to bookmarks. Flickr and let you make up your own tags, but it pays to first query on the tags you might use to check whether others have used them and how they did so. This is what leads to the self-organizing property of the keyword collections, and it's what gets some people so excited.

Lately, some webloggers have debated whether top-down or bottom-up taxonomy development is better, but it's clear to me that each has big advantages. The potential for a symbiotic relationship between the two approaches within the same organization should provide fertile ground for academic research projects.

Friday's big news in bottom-up taxonomy development was the announcement by Technorati, the weblog tracking site, that they'll support assignment of and searching by keywords on weblog entries. It's a big deal for web metadata because instead of creating yet another folksonomy, they're tying together the flickr and taxonomies to use with their tagging system, thereby providing a model to others thinking about taxonomies of web resource keywords. It's a big deal to people who think a lot about linking and markup because Technorati is letting people identify taxonomy terms by using the rel attribute of the HTML a element.

I mentioned above how the ability to enter a query on the use of a tag is key to the self-organization of a bottom-up taxonomy. Technorati lets us issue one query to simultaneously check for a term in the flickr collection, the collection, and any new weblog posts in Technorati index. I don't even have a Technorati account, but my queries there for terms I've used to tag flickr pictures and entries turned them up the relevant pictures and entries. For example, I saw that no one had used potrzebie as a keyword on either site, so I assigned it to one of my flickr pictures and one of my links, and a Technorati search found both shortly afterward.

Technorati offers several methods to add tags to your weblog post so that Technorati queries find it with the flickr pictures, links and other Technorati posts that use the same keyword (see Technorati's help page on this), but the most interesting method to me was the creation of an HTML link to the tag's page using a rel value of "tag", like this:

<a href="" rel="tag">[tagname]</a>

(As a longtime XML geek, I don't know whether to be amused or annoyed that the new special keyword is "tag". I try to stay amused.) I've written before about how little this attribute has been used, and I've even done a bit of research that found no use of it. As with a lot of optional metadata, people had little motivation to use this attribute because they didn't know of applications that would do anything useful with it. Now they do: a search engine that searches by metadata assigned to images and web pages from a taxonomy developed by anyone who wants to contribute to the taxonomy.

I created a dummy sample file on Friday and manually pinged Technorati with the URL, and so far it doesn't show up in query results for its keywords that I tagged using this markup. It has a link like the one above and another with similar href and rel values but no text between the a tags. If the latter one works, thereby letting us add metadata about our web pages to Technorati's index without displaying anything new on the page itself, that would be really cool. I'll add a comment below if it does.

Has anyone found whether it's possible to add a keyword to Technorati's index without including any link anchor text (for example, <href="" rel="tag"></a>)?


2005-01-17 17:44:26
Yeah, it's cool and that's about it.
I have my doubts about the immediate usefulness of this service. And I wonder if even the Technorati guys have any definite idea about how these blog tags will be used and what for. At present, it's nothing more than what everybody is calling it: cool

I talked about this stuff here in response to a post from David Weinberger.

2005-01-17 19:17:38
Yeah, it's cool and that's about it.
It's not just cool for cool's sake. It's cool because it's a significant step toward a metadata infrastructure for the web. The web has always been about data, with useful web metadata just being a pipe dream. Now that people have an incentive to add a common set of metadata to pictures, links, and weblog postings, new kinds of applications will become possible. (Note that Technorati, flickr, and all have APIs.)

It's not difficult to think of search terms for which a full-text Technorati search gets tons of chaff but a tag search gets a high percentage of useful hits. (Try "linking", for one.) That's the value of metadata. The problem with metadata has usually been giving people an incentive to enter it, and Technorati has made a real contribution here.

2005-01-17 23:20:56
Yeah, it's cool and that's about it.

The problem with metadata is that people lie.
2005-01-18 08:41:16
Yeah, it's cool and that's about it.
Yes, that's Google's problem with metadata. As a system of user-added (meta)data gets more popular, dishonest use of it increases, but it doesn't necessarily make the system unusable. People lie in their Amazon comments and Ebay ratings, but these lies are usually balanced out for a book or seller/buyer with a lot of ratings.