It’s been six months since I’ve posted anything about i-tags but the spec has been steadily evolving. Working Draft 03 has been posted on the i-tag wiki and there are some great new features. Quick highlights:
- The underlying RDF model has now been abstracted so it can be represented as either as microformat XHTML or as micro content XML (although only the former is defined in Working Draft 03 because the latter still lacks sufficient documentation).
- The new microformat defintion uses the XHTML
classattribute to structure the tag as a series of
links. This pattern, which editor Andy Dale suggested several months ago, has become a widely-used microformat design pattern.
- An i-tag is now divided into a header section and a body section. The header section consists of a set of links that use pre-defined classes (id, subject, author, publisher, verifier, date) to describe the i-tag itself (the RDF subject). The body section consists of a series of nested links that use globally-unique identifiers to identify the RDF predicate (the tag type) and RDF object (the tag value). This means i-tags can express an infinite variety of tag types all using the same simple format. See the spec for examples.
- All the globally-unique identifiers used for subjects, predicates, and objects in i-tags can be either URIs, IRIs, or XRIs.
- I-tag verification is now defined in detail, including both direct authentication using Yadis for authentication service discovery and third-party verification using an independent verification authority such as Opinity.
I-tags will be a topic at this week’s Internet Identity Workshop in Mountain View, CA. All the spec editors (Mary Hodder, Kaliya Hamlin, Andy Dale, and myself) will be there. Please join the session if you can, or send us feedback if you can’t attend in person.