so for this, i’ve decided on DeviceAtlas.  just head on over to DeviceAtlas and open a developers account – you will get a one year developer’s license to play around to see how cool it is.

after registering – click on the downloads link – then go to the php example and download the source files.  after de-tar-and-un-zipping the file, just extract the contents.  at the moment all we are really interested in, is the Mobi/Mtld/DA directory and its contents – also create a json directory and drop the Sample.json file inside.

dump everything into a web directory somewhere.

create a deviceatlas.php file in the working directory root and put the following inside.

//includes the DeviceAtlas API

include 'Mobi/Mtld/DA/Api.php';//fetch the previously populated apc cache instance into a variable

$tree = apc_fetch('tree');

//Get the properties from a variable containing a JSON tree loaded from cache

$properties = Mobi_Mtld_DA_Api::getProperties($tree, $_SERVER['HTTP_USER_AGENT']);

//Output the phone properties for your viewing pleasure

print_r($properties);

‘hhmmm, that’s it?’, you might ask, and if you were clever you would have noticed something strange in the code above.

yip, that is pretty much it – but you also need caching.  the apc_fetch(‘tree’) command in the code above actually fetches the json file already dumped into a ‘tree’ cache instance in PHP APC (Alternative PHP Cache).

why PHP APC, you may also ask.  well, besides using the overstated memcached (you might want to read this), there are some methods to the madness.  with PHP APC, the cache is shared on a server.  it might not be accessible from other servers, but this is not really a con in my mind.

if you wish to scale your application later one and add another server, there is going to be some issues, you might say – but there will also be issues if you have millions of users hit one central instance of DeviceAtlas.  so, having one instance of DeviceAtlas per server might not be too much of an issue.  also when it comes to updating the json file, you might want to consider the single point of failure issue of just having one server.

so have a couple of servers, and just write some scripts to update the single instances of DeviceAtlas, rather than updating one, already busy server which still needs a cache update.

but, back to business.

first you have to install PHP APC.  i found this handy guide on the net, which helped me install it on my debian system and integrate it with apache and php5 – there is also a guide at the bottom for fedora based machines, so don’t fret my linux loving friends

you can create a php script to run the following – which should cache your DeviceAtlas tree into PHP APC.

//ads the sample json data from DeviceAtlas

apc_add('tree', Mobi_Mtld_DA_Api::getTreeFromFile("json/Sample.json"));

from the first code example, the output might look something like this (depending on your phone)

Array
(
[wmv] => 0
[vendor] => Nokia
[mobileDevice] => 1
[memoryLimitMarkup] => 357000
[memoryLimitDownload] => 61440
[midiMonophonic] => 1
[midiPolyphonic] => 1
[mpeg4] => 1
[3gpp] => 1
[drmOmaForwardLock] => 1
[drmOmaCombinedDelivery] => 1
[drmOmaSeparateDelivery] => 1
[markup.xhtmlMp10] => 1
[markup.xhtmlBasic10] => 1
[image.Jpg] => 1
[image.Png] => 1
[amr] => 1
[mp3] => 1
[aac] => 1
[h263Type0InVideo] => 1
[gprs] => 1
[edge] => 1
[image.Gif87] => 1
[uriSchemeTel] => 0
[qcelp] => 0
[hsdpa] => 0
[amrInVideo] => 1
[3gpp2] => 0
[displayColorDepth] => 18
[model] => N70
[https] => 1
[image.Gif89a] => 0
[umts] => 0
[displayWidth] => 176
[displayHeight] => 208
[markup.xhtmlMp11] => 0
[markup.xhtmlMp12] => 0
[csd] => 0
[hscsd] => 0
[id] => 204255
[_matched] => NokiaN70
[_unmatched] => -1/5.0609.2.0.1 Series60/2.8 Profile/MIDP-2.0 Configuration/CLDC-1.1 UP.Link/6.3.1.13.0
)

you can view the attribute explanations here

now you can use the phone’s specific properties to your advantage.  you also might want to look at the user agent switcher add-on for firefox for testing purposes.

that’s it.  now every once in a while you can just update the json file, delete the current cache (http://www.php.net/manual/en/function.apc-delete.php) and bob’s your device detecting, apc caching uncle.

there is a great online community which supports mobile development called mobiforge which could be utilised to answer all of your mobile related questions.

but as a start i will point out some important steps/considerations to take/make:

user-centered design

before you start on any work, you have to realise that by doing a mobile site, the most important part of your equation is the user and his phone.  it is easy to develop/design a site which looks absolutely amazing in a pc browser, but fails to even load within a phone browser.

you have to make sacrifices in design/layout to suite the user of the site and understand the limitations your user might face with his specific mobile device.  people accessing a site with a lower end phone usually wants quick textual feedback about a certain subject, rather than big glossy images that fill your screen.  once you understand what the user need – and design according to those needs, then you will be ready to continue.

keep your site simple

it is easy in a web browser to go back in your history and traverse navigation, but on a mobile it is a bit different.  so why confuse the mobile user with 50 levels of navigation, where a simple three leveled hierarchy navigational solution would be more than sufficient

and remember that there is no need to overcomplicate things by adding features that is nice to have, rather than have to have.  it is a bad practice on mobile or pc.

prototype it

a while back i read a blog post written by phil barret, an user-experience guru , who used prototyping to do the layout of his new home using newspapers.  this is probably the best analogy you can use to describe the importance of prototyping your designs to control the flow of your site.

design for the right device

group mobile devices into specific groups, for e.g. low, middle and high.  where your low end would be your nokia 2610, middle would be sony ericsson w890 and the rest, high end devices, such as the iphone, palm and other feature rich pda devices.

it would make sense to deliver more text-based content to lower end phones and more graphic rich sites to high end phones.  and make sure your features apply to the phone’s capabilities.  you shouldn’t give someone the option of uploading images if his phone doesn’t support it.  this could be achieved by using something like tera-wurfl.

standardise

make sure you comply with the industry standards.  for e.g. using XHTML-MP as your markup language and something like WCSS as your presentation markup.  specify your doctype, character encoding and use well formed html code.  you can visit the oma for more information.

this gives you more flexibility and would cut down on rendering issues in your mobile browser.

this is only very basic advice, and by no means do i advocate this as being the most correct approach, but it should give you some direction and hopefully a bit of a mind shift when it comes to mobile development.

some usefull links:

• wap 2 specifications – http://www.wapforum.org/what/technical.htm
• XHTML-MP – http://www.openmobilealliance.org/tech/affiliates/wap/wap-277-xhtmlmp-20011029-a.pdf
• comparison between XHTML-MP and XHTML basic – http://pc.dev.mobi/?q=node/119
• mobile web best practices – http://www.w3.org/TR/mobile-bp/