Does content adaptation break the Web?

Last night I was privileged to give a talk to the London Web Standards Group on the W3C Mobile Web Best Practices [slides]. It was a very enjoyable evening with a very interesting, well-informed and skilful group of people. It was good to see so many people there and to make new friends. Thank you - I'm very much hoping to be there next month when Bruce Lawson gives his latest talk on HTML 5 (book early folks, it will be a sell out).

I cited the BBC News website as a prime example of thematic consistency: i.e. you get 'the news' whether you visit news.bbc.co.uk on a mobile or a desktop but that does not mean that you get exactly the same content on mobile and desktop. How could you? The desktop BBC news site has a great deal of content with links to background pieces, older stories on the same theme and so on. Mobile users get the headlines and links to more details but it's necessarily a more tightly targeted service. In my opinion this is the right approach. Trying to deliver the range of content on news.bbc.co.uk to mobile users is unlikely to be successful.

Jason Grant of Flexewebs, who I notice like me set his Twitter location to ZZ9 Plural Z Alpha in honour of the 30th anniversary of the Hitch Hiker's Guide to the Galaxy yesterday, pointed out that the BBC news site he saw on his Blackberry was the desktop version whereas an iPhone showed a more tailored version. What did I think? Simple: that the BBC's device detection needs sharpening up a tad! It's hard, don't get me wrong, accurate device detection does take a little effort, although things like dot Mobi's Device Atlas makes it more manageable (see this slide for details and links).

I was then taken to task by Justin Cormack who was somewhat incredulous that I, wearing my W3C hat, should be advocating device detection and content adaptation (see his Tweet).

I think you can see where I'm going here. Mobile users and desktop users are clearly in very different contexts. As an example: if I'm looking at the Internet Movie Database on my desktop, I am probably going to browse around for a while, look at film reviews and so on. I also use IMDB on my mobile when watching TV because I want an answer to the age old question "who's that actor, I know I've seen him/her before…" Same person, same building (I work from home) but: different device, different context.

We discussed whether device detection was itself enough to determine context and user preferences. Clearly no, it isn't. A user may well want the full desktop version on their mobile or vice versa. No 'reason' is required other than the fact that the user has asked for it. Hence, good practice is to include a link to the full desktop version from mobile and vice versa. But for a lot of users, I dare to say the majority, device detection will be a pretty good guide as to which version of a site a user is more likely to want.

Now, ideally, there is only one version of any page. For simple pages that's true. But for complex pages you're very likely to want to create quite different experiences and, again, I refer to the BBC News site as an obvious example. So with all that noted, yes, I do think varying the content according to the device you're delivering to is a good thing to do. And yes, this is entirely consistent with Web Architecture.

My argument is that this is just a different version of content negotiation. As an example, visit http://www.w3.org/2007/05/powder-s with a browser and you'll get an HTML page. Visit the same URI with a user agent that sends the HTTP Accept Header with application/rdf+xml media type and you get back RDF/XML. That's not breaking the Web, that's delivering the most appropriate representation of the requested resource given the available information about the user agent.

The One Web philosophy flows from this as I emphasised (perhaps rather more strongly than was strictly necessary). There must be one URI that returns thematically-consistent content. If an HTTP request to that URI returns a 302 Found response that takes me to a different URI where the mobile or desktop version is located, that's fine. Just don't ever ask a user to have to choose whether they enter the mobile or desktop URI - that really is failure.

13 October 2009
Although I believe the views here to be fully consistent with W3C Mobile Web best Practices, they are my own and should be treated as personal opinion only.
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