On 27/2/09 16:12, Andrew Maben wrote:
There seem to be some Microformats proponents on the list, but I don't
recall much mention of RDFa.
I wonder if anyone has any thoughts on their relative merits, both
immediately and in the longer term?
It might be helpful if you described the problem you're hoping to solve
with either, but anyway here are some thoughts under four headings.
+ Parser interoperability
I don't have first-hand experience with implementing a parser, but I
suspect how XHTML+RDFa should be parsed into RDF triples is better
specified than how HTML4 and XHTML1 microformats should be parsed into
data. The microformats community is still working on parsing specs, but
the XHTML+RDFa standard includes parsing specs:
http://www.w3.org/TR/rdfa-syntax/#s_rdfaindetail
http://microformats.org/wiki/parsing
+ HTML compatibility
You are supposed to be able to express microformats in conforming HTML
4.01 as well as XHTML 1.x. This has been partially achieved in the sense
that no microformat requires you to write HTML 4.01 that does not meet
its SGML validity requirements, though some accepted microformat
patterns do (arguably, at least) abuse HTML4 elements and attributes.
By contrast, RDFa has only been specified for XHTML. However, Internet
Explorer - the most popular browser - does not support XHTML. The
guidance for how authors should serve XHTML family documents as
text/html is still being written (by the XHTML 2 WG):
http://www.w3.org/MarkUp/Drafts/#xhtml-media-types
Worse, there is no standard yet for how RDFa should be treated when
served as text/html rather than XML. This will be defined by the HTML
WG/WHATWG, who are working on the next version of the HTML standard and
are currently unpersuaded of the need to support RDFa:
http://www.w3.org/html/wg/
http://www.whatwg.org/
http://tinyurl.com/bbx75q [public-h...@w3.org archives]
http://tinyurl.com/akjzm3 [wha...@whatwg.org archives]
+ Accessibility
Microformats create minor accessibility problems when you need to
include machine-parseable data that is equivalent or supplementary to
human-friendly visible information. The microformats community is still
working on better approaches to including such information.
http://www.webstandards.org/2007/04/27/haccessibility/
http://www.bbc.co.uk/blogs/radiolabs/2008/06/removing_microformats_from_bbc.shtml
http://microformats.org/wiki/machine-data
RDFa does not create the same problems, because it adds extension points
for this purpose (the content attribute on every element, primarily).
http://www.w3.org/TR/rdfa-syntax/#rdfa-attributes
+ Distributed extensibility
You can unilaterally make up your own vocabulary in RDFa, but not
microformats, which must be developed and standardized through the
microformats community process. (Of course, you can make up markup
patterns that can be used to extract metadata - but those aren't
official microformats.) Whether this is good or bad perhaps depends on
how widely useful your vocabulary would be.
--
Benjamin Hawkes-Lewis
***
List Guidelines: http://webstandardsgroup.org/mail/guidelines.cfm
Unsubscribe: http://webstandardsgroup.org/join/unsubscribe.cfm
Help: memberh...@webstandardsgroup.org
***
