This post is part of a three-part series that analyses the differences in features and syntax between microdata and RDFa. The series attempts:
- to identify the differences in approach and functionality of the two languages, which should help developers choose between them
- to identify any guidelines for developers of vocabularies for use with both languages
- to identify a subset of functionality that is common between the two languages, which developers might want to stick to to make switching and mixing easier
- to identify mapping rules that might be applied to automatically or manually map from one language to another if the simple subset is used
I’ve done this by looking at converting microdata examples to RDFa and vice versa, and the lessons to be drawn from that exercise. The three posts are on:
This post is the first of these, which looks at how microdata might be mapped to RDFa, in terms of generating the same RDF according to the microdata-to-RDF mapping rules that I outlined in my post on Microdata + RDF.
As part of the ongoing discussion about how to reconcile RDFa and microdata (if at all), Nathan Rixham has put together a suggested Microdata RDFa Merge which brings together parts of microdata and parts of RDFa, creating a completely new set of attributes, but a parsing model that more or less follows microdata’s.
I want here to put forward another possibility to the debate. I should say that this is just some noodling on my part as a way of exploring options, not any kind of official position on the behalf of the W3C or the TAG or any other body that you might associate me with, nor even a decided position on my part.
- large-scale consumers such as search engines
- small-scale consumers that provide us with a useful service
- specialist consumers that are interested specifically in our data
and the requirement to use multiple, incrementally more specialised, vocabularies to describe the same things as a result.
What I want to do here is explore how a publisher might handle this kind of situation using microdata. The ground has already been substantially covered by Stéphane Corlosquet; what I do here is work through an example where the consumers are microdata’s primary targets – search engines and browsers – look at why it’s hard to fix this within microdata itself, and discuss how people who create vocabularies to be used with microdata might help publishers who find themselves in this situation by designing those vocabularies to be used together as well as on their own.
One of the things that’s been niggling at the back of my mind since the schema.org announcement is how small a role search engine results plays in the wider data sharing efforts that I’m more familiar with in my work on legislation.gov.uk, and more generally how my day job experience differs from (what seem to be) more common experiences of development on the web. In this post, I’m going to talk about that experience, and about the particular problems that I see with the coexistence of microdata and RDFa as a result.
If you’ve hung around in linked data circles for any amount of time, you’ll probably have come across the httpRange-14 issue. This was an issue placed before the W3C TAG years and years ago which has become a permathread on semantic web and linked data mailing lists. The basic question (or my interpretation of it) is:
Given that URIs can sometimes be used to name things that aren’t on the web (eg the novel Moby Dick) and sometimes things that are (eg the Wikipedia page about Moby Dick), how can you tell, for a given URI, how it’s being used so that you can work out what a statement (say, about its author) means?