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Archive for August 27th, 2010

New W3C Document Standards for XHTML and RDFa

Posted by Brian Kelly on 27 August 2010

New W3C Draft Documents

The W3C have recently announced that new “Drafts of RDFa Core 1.1 and XHTML+RDFa 1.1 [have been] Published“. The announcement states that:

The RDFa Working Group has just published two Working Drafts: RDFa Core 1.1 and XHTML+RDFa 1.1. RDFa Core 1.1 is a specification for attributes to express structured data in any markup language. The embedded data already available in the markup language (e.g., XHTML) is reused by the RDFa markup, so that publishers don’t need to repeat significant data in the document content. XHTML+RDFa 1.1 is an XHTML family markup language. That extends the XHTML 1.1 markup language with the attributes defined in RDFa Core 1.1.

Meanwhile on 24th June 2010 the latest version of the “HTML5: A vocabulary and associated APIs for HTML and XHTML” working draft was published.

Patrick Lauke’s talk on “HTML5 (and friends): The future of web technologies – today” generated a lot of interest at the IWMW 2010 event – but as I pointed out in the workshop conclusions session, there seems to be some uncertainty as to whether the focus for those involved in the provision of institutional Web services should be on the user interface developments provided in HTML5 or in use of HTML as a contained for reusable (linked) data which RDFa aims to provide.

Of course for many the requirement will be to enhance the user interface (for human visitors) and provide access to machine readable data (for machines). The latter can be achieved in various ways but if you choose to go down the RDFa route a  question then is: “Can you embed RDFa in HTML5 documents and, of so, how do you do this?“.

The answer to this question is not (yet) clear.  The W3C have published a  “HTML5+RDFa: A mechanism for embedding RDF in HTML” working draft document – but this was released in July 2009 and hasn’t been updated since [Note that while this document on the dev.w3c.org Web site has not been updated or links to new versions provided, as described in a comment to this post a more recent document on HTML+RDFa 1.1: Support for RDFa in HTML4 and HTML5, dated 24 June 2010 is available – this comment added on 2 September 2010].

This document also states that:

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.

But such caveats are also true of the RDFa Core 1.1 and XHTML+RDFa 1.1 draft documents, both of which state that:

This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress

In addition the HTML5 working draft states that:

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.

Meanwhile the “HTML Microdata” working draft was also published on 10th August 2010, and this again states that:

Implementors should be aware that this specification is not stable. Implementors who are not taking part in the discussions are likely to find the specification changing out from under them in incompatible ways. Vendors interested in implementing this specification before it eventually reaches the Candidate Recommendation stage should join the aforementioned mailing lists and take part in the discussions.

Microdata is being proposed as an extension of microformats which addresses deficiencies in microformats without the added complexities of  RDFa.

What Does the Future Hold?

Should you start to migrate HTML documents from an existing HTML 4 or XHTML 1 environment to HTML5?  The advice given by Patrick Lauke in his talk, as reported by @iwmwlive, was “If you want to take advantage of the new features, go ahead with HTML5, but don’t rush off to recode if you don’t need it“.  But while much of the buzz surrounding the new features provided by HTML5 concern user interface developments (such as native support for video and  enhanced forms validation) the future regarding use of HTML as a container for data seems to be somewhat uncertain.

The best advice may be not to rush off to embed data in your HTML resource if you don’t need to.  But as such advice can be a barrier to innovation if needs to be qualified by the suggestion that if you do wish to embed data using RDFa, microdata of microformats, you should ensure that you do so using a management system which will enable you to change the format you use if you discover that you have selected an approach which fails to take off.  This advice is, of course, reflects the warning given in the draft documents – but not everyone reads such advice!

Posted in HTML, standards, W3C | 4 Comments »