Mobilising a Website, Part 2: Strategies

Posted in Mobile, PHP, Programming and Zend Framework on Saturday, the 26th of July, 2008.

Tagged: , and

In Mobilising a Website, Part 1: The Problem I noted that this site is practically unusable when viewed using the browser on a mobile handset, and that I'd like to do something about that.

This time around, I'd like to size up some of the approaches and strategies that developers can take in order to make an existing website mobile-friendly.

Option 1: Do Nothing

It may sound flippant, but in the world of development, the option of doing nothing often has to be seriously considered. Every developer out there can recount tales of ridiculous amounts of time and expense being invested in hairbrained projects developing systems that simply were not needed.

The "do nothing" strategy is unparalleled in its cost-effectiveness and simplicity and is naturally very, very easy to estimate and plan.

In this particular case, we could point to the fact that, as we saw, some high-end handsets do a decent enough job of displaying the site as it stands. We can confidently expect mobile browser technology to improve immeasurably over the next couple of years, so there's a lot to be said for holding off.

Unfortunately, this strategy does not solve the original problem. I want my site to work nicely for mobile users now, and it will be a long time before browsers as capable as that of the iPhone dribble down to the majority of consumers.

Moreover, I'm as interested in the process of achieving a mobile-friendly site as I am in the finished article, and that's why we're here: this series of blog posts would be rendered rather brief and anti-climactic if I were to choose the "do nothing" route!

Option 2: Add a Mobile Stylesheet

Quite a few of the problems we saw in part one, in particular those which confounded the Nokia 6230i, were related to the site's stylesheet. For example, both the fixed width of the page and the large banner images are defined in there. The former is the result of the rule width: 790px; being applied to a number of the elements within the page; the latter is specified by applying a background-image property to a <div />.

Fortunately, HTML and XHTML provide a way of specifying that a stylesheet only applies to a certain class of device. This is all achieved by applying a media attribute to the <link /> element which calls in the stylesheet.

By way of an example, the following code extract is designed to send one stylesheet to "full" or desktop web browsers (media="screen") and an alternative stylesheet to mobile browsers (media="handheld"):

<link rel="stylesheet" type="text/css"
		media="screen" href="full.css">;
<link rel="stylesheet" type="text/css"
		media="handheld" href="mobile.css">;

The full list of possible values for the media attribute can be found here.

Once we're serving a different stylesheet to mobile devices, we can really start to think about customising the user experience for them. For example, a mobile stylesheet could also be used to "hide" certain elements from mobile browsers, by applying a display: none; style rule to them. The long list of links in the sidebar which made the site so difficult to use with the W880i seems like a good candidate for hiding.

This strategy has the compelling benefit of simplicity. By adding one line of HTML, plus a small additional stylesheet to the site we may be able to deliver a mobile-friendly experience. Let's knock up a prototype mobile stylesheet and see how things look.

Here's a small CSS file that "hides" some of the more spurious elements of the page. I'll also specify that links should be displayed in green, purely to make it unambiguous as to whether the new stylesheet is being loaded and applied.

.sidebar {
	display: none;
a {
	color: green;

Remember that simply by not specifying widths, colours and background images in there, we're sidestepping a lot of the decorative fluff that was causing problems for mobile browsers.

Viewed on the Sony Ericsson, things are looking up: homepage viewed on a Sony Ericsson W880i

Fig 1: with a handheld stylesheet, viewed on a Sony Ericsson W880i

We're successfully displaying only the main navigation, an introductory heading and paragraph, 10 links to blog posts and a footer. It's actually a really clean user experience for very little effort - I like it a lot.

Unfortunately, life isn't quite so cheerful for users of the other handsets. The experience on the Nokia 6230i and the iPhone is all but unchanged, but probably for different reasons. The Nokia does occasionally display links in green, so my hunch is that it simply does not support the media attribute, and so loads and applies both stylesheets. There's no corresponding property in WURFL to confirm it, but it certainly looks that way.

Conversely, I'm certain that the iPhone fully understands the media attribute, but considers itself to be a "real" computer. The jury's out on that one [1]. My gut feeling is that screen size should be the deciding factor in these cases, and based on that, the iPhone sits squarely under the heading of a handheld device. It's only fair to point out that the iPhone is not alone in this behaviour: the Nokia N95 and my LG KU990 behave in much the same way.

So the handheld stylesheet seemed like a great idea, but we can summarise several of the drawbacks to this approach as follows:

So this strategy isn't ideal. But for so little effort I've actually managed to make the site perfectly usable on a number of handsets. With little to lose, and with Early And Regular Delivery in mind, I'm actually going to put the handheld stylesheet in place right now, while I ponder alternative stategies.

Option 3: Allow the Site Automatically to Adapt to Devices

The principle behind this strategy is one known as "adaptive rendering". In other words, device detection would be done server-side (in my case using PHP) and the client would be sent markup and content tailored specifically to the device. I can think of a couple of ways to achieve this, although I'm sure there are plenty more.

The first option is afforded to us by the fact that the site is based firmly on the MVC pattern, which is fairly common in web sites and applications these days. MVC dictates that the business logic and data (Model), display logic (View) and application flow (Controller) be arranged into discrete components, so as to be independent of each other. In this case we're primarily concerned with the display logic, so it seems feasible to take advantage of the separation and swap in a different View component for mobile devices.

I happen to be using Zend Framework, so this could be achieved by specifying the directory in which the View should look for view scripts and helpers. I imagine it would not be difficult to do this dynamically using methods such as Zend_View_Abstract's setBasePath(), setScriptPath() and setHelperPath().

Another approach would be to adopt the "two-step view" pattern. This pattern is nicely documented by Martin Fowler in his classic Patterns of Enterprise Application Architecture, so I'll quote liberally from there:

Two Step View [splits] the transformation into two stages. The first transforms the model data into a logical presentation without any specific formatting; the second converts that logical presentation with the actual formatting needed. This can support multiple output looks and feels with one second stage each

That sounds rather like what I need. I guess in terms of implementation, I'd be looking at having the first stage generating some common XML format, and then perhaps using XSL Transformations server-side in order to transform the XML into the markup which the device prefers. At the same time, I can opt not to include certain elements, such as the long list of links, in the finished pages.

Again, this can all be done within the View component of the site's code, which is rather gratifying. Still, that does seem like quite a lot of work, and I'm not sure I want to get into what would effectively be writing my own templating engine.

Option 4: Build a Separate Mobile Site

One surefire way of getting myself a working mobile version of the site would be to simply build a standalone mobile site. I've already registered the domain name, and quite honestly do not have any better ideas for what to do with it.

The benefits of this approach would be that I could tailor the mobile site exactly the way I want it, I could roll out features incrementally, and I wouldn't risk making the main site's code any more complex than it need be. Admittedly it's pretty simple stuff right now, but I'd like to keep it that way.

I could detect mobile devices as they hit the main site (perhaps using Tera-WURFL) and forward them across to the mobile version. This is a strategy used by a fair number of large sites, such as Flickr (mobile version) and Facebook (mobile version), so it seems like I'd be in good company.

The downsides would be that I would have two sites to maintain, and that I still would not have solved the original problem, that of being a bit of a dog when viewed on a mobile browser. That said, if I leave the handheld stylesheet in place, I'd be catering to most cases.

The important thing to remember will be to always provide a link back to the full site for users who feel confident that their browsers will cope with it. I'm not interested in forbidding any users from accessing any content whatsoever: that's too much of a throwback to the dark days of the desktop web when sites would block, say, Opera users, demanding that they to "upgrade" to IE5 in order to gain access.


Creating a standalone mobile-friendly site - either under the .mobi domain or under an "m." subdomain - and forwarding mobile devices on to it is an appealing option, and it's the one towards which I'm leaning right now. I think...

I may well change my mind and opt for the adaptive rendering path. While that route feels a little more ambitious, I certainly would be quite proud if I could pull it off, and have the site adapt itself to devices as if by magic.

Either way, I'm going to have to put some thought into which tools and libraries I'm going to use to create mobile-friendly pages. There's a few out there, some of which I've covered on this site, some in a recent piece I wrote for php|architect, and yet others with which I'm not at all familiar.

Part 3 of this series seems like a good time to start making some decisions about toolkits, and this will in turn entail making some architectural decisions about the code behind the mobile version of


[1] Similarly, the debate about whether to deliver "full web" content or a mobile tailored version to such devices continues. A useful piece on the subject appeared recently over at WAP Review.

Many thanks to my colleague Dan Gent, whose remarkably well-timed loan of Cameron Moll's Mobile Web Design helped to inform this post.

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Posted by Ciaran McNulty on Monday, the 28th of July, 2008.

Interesting points.

Just so you know, that post full of YouTube links works just fine on the iPhone!

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