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July 25, 2005

Understanding true decentralisation - the microformat model

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Posted by Kevin Marks

Jeff Jarvis called for decentralised tags and restaurant reviews, and Stowe Boyd posted some ideas about how to achieve this.

Unfortunately, Stowe misunderstood how the existing open, decentralised tagging model works, and went off into a design dead-end because of this.

Stowe confuses the tagspace linked to (which provides the context for the meaning of the tag), with the services that can index the tag. These are completely independent. You can link to Technorati, your own site, Wikipedia or anyone who provides a tagspace with a URL that ends in the tag you want - for example:

<a href="" rel="tag">Get real</a> 
<a href="" rel="tag" >decentralisation</a>,
<a href=" Boyd" rel="tag" >Stowe Boyd</a>

which displays as:
, .
This will tag this post with 'getreal', 'decentralisation' and 'Stowe Boyd', while providing informative links on each tag.

Similarly, anyone can index the tags provided this way. They are open and loosely coupled. Technorati indexes all links with rel="tag" on as tags, independent of which site they link to. We designed the spec that way from day one to avoid lock-in, and encourage adoption. When he says "If I want to get today's Technorati to work, I still need to create URLs that are Technorati specific", he is completely wrong.

Stowe then spends a lot of space worrying about the problem of where he links to, as if this is set in stone at the time of posting. This is not just premature optimisation, it's optimising for a nonexistent problem. Because you control your own data on your own blog, if you later decide to link to a different tagspace, you can change your own links; you don't need an elaborate and fragile RSS hybrid with mandated behaviour to do so. The choice of tagspace is an important one, but I would contend that Technorati's page that collates posts from anyone that uses that tag in a blog, and also on photo and like services like Flickr, Buzznet, and Furl is more open than a solipsistic category on your own site. However, if like Humpty-Dumpty, you decide that "When I use a word, it means just what I choose it to mean - neither more nor less", you can use your own personal tagspace to clarify this.

Owning your own data is the key point.

The microformats model is to encode common data formats in XHTML so you can put the data on your own blog, and multiple tools can take advantage of it. Your data can travel inside webpages, feeds, and anywhere else HTML, RSS, Atom, or any future XML format can go, without having to build elaborate new infrastructure to make it work.
Adding new specialised RSS-only feeds for this, and requiring indexers to poll them, as Stowe suggests, is far more work than adding rel="tag" to a few links, and little bits of extra work like that don't get done - after all the sidebar link to my posts on this blog still shows an error after 10 months here (note: use the W3C link checker to easily find such problems).

Doing things openly is more work than building a proprietary site to edit your data, but we think ti is worth the benefits. Lets look at the example of tagging restaurant reviews that both Jeff and Stowe mention.
The microformat way to do this is to use hReview, an open standard for publishing reviews. I missed Stowe's original post because I was down on the coast on Friday, so here's a review of the restaurant I had lunch in:

Wonderful seafood, workmanlike ambience

Jul 22, 2005 by Kevin Marks
Phil's Fish Market
7600 Sandholdt Rd.
Moss Landing, CA 95039

★★★★★ Phil's is tucked away in between the docks and the beach in , where it gets first pick of the landed there each day, and cooks up delicious fresh dishes that would cost 3 times as much in SF. Resolutely unostentatious, you order food by lining up at the cash register, and while you can sit , the seats face the power station opposite the front, rather than the beach at the back.

Technorati and other comprehensive blog indexers will pick up the 'seafood','fish', 'outside' and 'Moss Landing' tags from that and associate them with this post, but a specialised service looking for reviews could see them in the context of the 'hreview' class, and use the more structured rating data to make more sense of it.

It would be easier to build a closed restaurant rating service that required you to come to it to fill in and store your reviews, but it is easier and better for independent publishers to own their own data.

Stowe, I'm glad you're interested in Open Tagging, and I hope I've explained it better now. Do come along to Tag Tuesday's July meeting tomorrow 6:30pm - 9:30pm at 77 Natoma Street in SF and talk to me and other Open Tagging developers about it (yes, that event is a microformat too).

"The question is," said Alice, "whether you can make words mean so many different things."

"The question is," said Humpty Dumpty, "which is to be master - that's all."

Technorati Tags: , ,

Comments (7) | Category:


1. Aaron Suggs on July 25, 2005 8:22 PM writes...

But how does an aggregator service (say Technorati) know what the tags refer to?

That is, if I have a sidebar on my blog of my links, and each link has a few rel="tag" links after it, how does Technorati know those tags refer to the delicious link? How does Technorati realize that rel="tag" links after a blog post refer to just that post, and not the entire weblog?

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2. Kevin Marks on July 26, 2005 12:24 AM writes...

That is a good question, Aaron. Let me answer the second part first - the tags for a post are supposed to be part of the post (as in my examples above), not 'after' the post. A misplaced sense of tidyness makes some people put the tags between the posts, and omit them from feeds, which does make it hard to determine which post they belong to.

As for associating tags with a link, hReview as shown above is one way to do this; another proposal for an open link-tagging microformat is xFolk:

This is an area still being developed.

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3. Luistxo on July 26, 2005 2:40 AM writes...

We've begun, a way to tag places on maps. Restaurants as well, if the users want.

Look for food in Cleveland, for instance

It's the model applied to Google Maps with its API as the background.

Of course, not only restaurants. People are tagging many different things, including themselves (personal location), as in the
The Peak Oil community map:

- Wifi communities, like this in a Barcelona district:

- Bookcrossing mapped as well:

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4. Stowe Boyd on July 26, 2005 9:59 AM writes...

Kevin - I can't find the trackback url, so here's my response:

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5. Bill Seitz on July 26, 2005 11:55 AM writes...

I think of every WikiWord as a tag.

If I tweak my WikiEngine to render every WikiWord link as having a rel=tag param, will Technorati pick up every one of those references?

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6. Meghan Strader on July 26, 2005 11:20 PM writes...

Some web communities are arising that serve to counteract the force of decentralization. On my site,, each user creates a personal link directory complete with hierarchical folders and arbitrary labelling. I created this site precisely because the web is never going to be organized, and some of us appreciate being able to organize our view of it. The primary means of establishing a new Connectedy account is exporting one's browser bookmarks. The real benefit is accessing them from any computer and sharing them with other web users.

Permalink to Comment

7. paolo on July 27, 2005 12:13 PM writes...

There is a small problem anyway: overloading of class attribute.

In my blog, I already use the 'class="summary"' for the title of posts and the CSS makes class="summary" elements bigger.
In this way, when I post in my blog an hCalendar event, the title of the event is as big as the title of my posts.

I would suggest to add in the wiki pages at
a CSS that can be easily added to your blog. This additional CSS will "overwrite" the default settings of your normal CSS for the .vevent subelements.

Something like
.vevent .summary {
//remove all the previously set properties, for example:
text-decoration: none;
font-size: 100%;

Since the hCalendar microformat is the following,
<span class="vevent">
<a class="url" href="">
<span class="summary">Web 2.0 Conference</span>:

I hope to have been clear but I'm not so sure ;-)

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