RDFa

What can I say…this post has everything.

First, it shows how Egon has used RDFa to mark-up HTML documents with information about molecules–something he started doing last year. But then it shows how he uses the latest version of Operator (0.8) to parse the RDFa, and generate menus which will search chemistry databases.

What’s most interesting about this post for me, is that Egon actually went through the process of doing all of this by using a GreaseMonkey script first, before he then used Operator to do the heavy lifting. GreaseMonkey is great for general purpose processing on a page, but the important thing about extensions like Operator is that they deal with your page at the semantic level. It then makes it very easy to do the type of thing that Egon has done, and add a menu item that searches a specific database. By talking us through the ‘long-hand’ technique we start to see the real benefits of Operator.

I’m looking forward to the next instalment, because I think Egon’s on a roll here!

The Simile project at MIT has been developing fantastic tools to let you manage interoperable data on the web without a backend database. In particular, David Huynh’s Exhibit project lets you present structured data in a beautiful, dynamic, JavaScript-driven way, again without a backend database (see their US Presidents example).

One issue Exhibit has been struggling with is that, if the data is in JavaScript, and it isn’t rendered in HTML until the JavaScript takes over, search engines may not be able to index the content. As of version 2.0, thanks to Keith Alexander, Exhibit will support an RDFa importer: the data can be expressed in simple HTML with RDFa, and the Exhibit code will replace this basic HTML with the more dynamic, navigable version. Yet the search engines will still be able to see the full content, without having to type anything in twice. That’s the power of interoperable data in HTML: all tools that currently depend on HTML still work, while tools that require greater structure are built without repeating the underlying data.

And once more Bob DuCharme has written an exquisite article, published by IBM developerWorks, called Put XHTML 2 to work now. To sum up the main idea of the article:

Many publishers that store content in XML have always known that using an existing, standard schema (by which I mean a W3C Schema, a RELAX NG schema, or a DTD) was better than creating their own from scratch. They looked at DocBook and found it too complex; they looked at HTML or XHTML 1 and found it too simple. For many of them, XHTML 2 will hit a sweet spot between the richness of DocBook and the simplicity of XHTML 1 that makes it a perfectly good format for storing content, whether that content has to be converted to other formats for delivery in various media or not.

What I liked best? The section Easier addition of metadata, where he writes about RDFa

Bruce D’Arcus announced in semantic-web@w3.org that the OASIS OpenDocument Metadata Subcommittee works on a proposal for enhanced metadata support in their file format:

A quick summary is that we’ve adopted RDF as the model for metadata, which can be:

• embedded as RDF/XML in the file package to describe either the document, or embedded content
• used in an RDFa-like syntax to tag content as triples (where the content is the literal object)
• hooked up to a new generic field (text:meta-field)

Note: For further discussions on this topic see also http://lists.oasis-open.org/archives/office/.