Yesterday I exercised poetic license when I suggested that Adobe’s Extensible metadata platform (XMP) was not only the spiritual cousin of microformats like hCalendar but also, perhaps, more likely to see widespread use in the near term. My poetic license was revoked, though, in a couple of comments:
Mike Linksvayer: How someone as massively clued-in as Jon Udell could be so misled as to describe XMP as a microformat is beyond me.
Danny Ayers: Like Mike I don’t really understand Jon’s references to microformats – I first assumed he meant XMP could be replaced with a uF.
Actually, I’m serious about this. If I step back and ask myself what are the essential qualities of a microformat, it’s a short list:
- A small chunk of machine-readable metadata,
- embedded in a document.
XMP is embedded in a binary file, completely opaque to nearly all users; microformats put a premium on (practically require) colocation of metadata with human-visible HTML.
Yes, I understand. And as someone who is composing this blog entry as XHTML, in emacs, using a semantic CSS tag that will enable me to search for quotes by Mike Linksvayer and find the above fragment, I’m obviously all about metadata coexisting with human-readable HTML. And I’ve been applying this technique since long before I ever heard the term microformats — my own term was originally microcontent.
But some things that have mattered to me in my ivory tower, like “colocation of metadata with human-visible HTML,” matter to almost nobody else. In the real world, people have been waiting — still are waiting — for widespread deployment of the tools that will enable them to embed chunks of metadata in documents, work with that metadata in-place, and exchange it.
We’ll get there, I hope and pray. But when we finally do, how different are these two scenarios, really?
- I use an interactive editor to create the chunk of metadata I embed in a blog posting.
- I use an interactive editor to create the chunk of metadata I embed in a photo.
Now there is, as Mike points out, a big philosophical difference between XMP, which aims for arbitrary extensibility, and fixed-function microformats that target specific things like calendar events. But in practice, from the programmer’s perspective, here’s what I observe.
Hand me an HTML document containing a microformat instance and I will cast about in search of tools to parse it, find a variety of ones that sort of work, and then wrestle with the details.
Hand me an image file containing an XMP fragment and, lo and behold, it’s the same story!
In both of these cases, there either will or won’t be enough use of these formats to kickstart the kind of virtuous cycle where production of the formats gets reasonably well normalized. In the ivory tower we pretend that the formats matter above all, and we argue endlessly about them. Personally I’d rather see what I’d consider to be a simpler and cleaner XMP. Others will doubtless argue that XMP doesn’t go far enough in its embrace of semantic web standards. But when we have that argument we are missing the point. What matters is use. This method of embedding metadata in photos is going to be used a whole lot, and in ways that are very like how I’ve been imagining microformats would be used.
per for this comment, Scott Dart informs me that PNG (and to a lesser extent GIF) can embed arbitrary metadata, but that support for those embeddings regrettably didn’t make the cut in .NET Framework 3.0.