If many Web page owners act on Schema.org’s suggestions, more than just search will benefit. “This data can be used by any software to cross-correlate things that are related, or to understand the relationship between information from different sources,” says McCleod. For example, widespread availability of semantic information might improve artificially intelligent assistants, such as Siri (bought last year by Apple). Or tools able to make good recommendations of, say, news articles because they can know for sure what stories are referring to.
However, the companies behind Schema.org made their move unilaterally, without consulting the World Wide Web consortium (W3C), the standards body for Web technology. “We had no idea this was coming,” says Manu Sporny, a member of the W3C’s Semantic Web Coordination Group.
Schema.org asks for semantic markup to be written using a format known as microdata, which is not yet a W3C standard, rather than RDFa, a more widely used W3C-approved alternative.
Google has warned that its “crawlers” that roam the Web to build its index could be confused by a page using both microdata and RDFa. Yet Microsoft has previously said its own crawlers have no such problems, says Sporny.
If that confusion isn’t straightened out, he says, microdata may become the only standard used at any scale, which would limit the power of the semantic Web, because the alternative can do much more. “RDFa supports use cases that microdata can’t—for example, the WHO publishing mortality rates for different countries or adding semantic information to eBook or image files,” he says.
Sporny hopes that Google and others behind Schema.org will modify their stance on formats. But he acknowledges that having such large companies embrace the semantic approach is a good thing. “They are saying you will get better results with semantic Web concepts,” says Sporny, “and if they encourage more sites to embrace the semantic Web, that will help all kinds of other applications, too.”