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Re: Why bound prefixes are an anti-pattern in language design

From: Danny Ayers <danny.ayers@gmail.com>
Date: Wed, 12 Aug 2009 23:54:08 +0200
Message-ID: <1f2ed5cd0908121454h2837e1b3n987ffbde811fc12d@mail.gmail.com>
To: Ian Hickson <ian@hixie.ch>
Cc: Martin McEvoy <martin@weborganics.co.uk>, RDFa Developers <public-rdf-in-xhtml-tf@w3.org>
2009/8/12 Ian Hickson <ian@hixie.ch>:

 Microdata is more resilient to this behaviour than RDFa. This is
> not an accident, it is a design decision. I believe it is a prerequisite
> for this kind of technology: where we can make our languages resilient to
> copy-and-paste, we must do so.

Do you mean resilience in this sense:
[[
In computer networking: “Resilience is the ability to provide and
maintain an acceptable level of service in the face of faults and
challenges to normal operation.”
]] http://en.wikipedia.org/wiki/Resilience_(network)
?

If so, I'd suggest that making allowances for spec-naive copy & paste
operations is unlikely to provide an acceptable level of service in
the context of embedded data.

When an author wishes to communicate information in a given medium,
they need awareness of how the medium will be interpreted. With
structural (& presentational) markup used over text-based messages,
the communication of the message tends to be very robust in the face
of markup faults. The human looking at a badly rendered Web page still
has a good chance of interpreting the information contained in the
page that the author intended, because most of the information is
expressed in a human language.

With embedded machine-readable data, there's at least one extra step
in interpretation: the part where the machine gets it. In this step
the use of heuristics to grok the message is unacceptable - for the
reason that if the author wishes to express explicit data, there wish
should be faithfully recognised. By making allowances for markup
errors in this context, the original intent is clouded by the
heuristics.

For all the obvious reasons I don't think document-level Draconian
error handling is appropriate for HTML (although it does have its
place elsewhere on the Web). But by the same token I think it would be
doing an injustice to authors who get their markup correct to disallow
a best-effort trust agreement between them and their ultimate audience
by passing through best-guess material with the same authority.

In practise I think this means a strict interpretation mechanism is
desirable at the statement level, but with ignore-if-fail, so the
information communicated by documents (and their embedded data) can be
maximally conveyed. I reckon this is generally consistent with the
rest of HTML5 design.

Thing is, I'm not sure the microdata spec in its current form can
support this, while the RDFa approach almost certainly can. Remember
looser interpretation should be (and in both cases is) possible
further down the chain, depending on the client application.

Cheers,
Danny.

-- 
http://danny.ayers.name
Received on Wednesday, 12 August 2009 21:54:59 GMT

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