Web Applications on PDAs

A few months ago, the company I work for wanted me to migrate our existing application to PDAs or smartphones. As I’d never developed for this environment before I began to research for it. It isn’t a definitive document but simply lists various ideas and capabilities of handheld devices to operate web applications.

Hardware – PDA or Smartphone?

Currently most mobiles have some kind of browser built in, so theoretically many would not have to upgrade their mobile to use the application. However, it is preferred to support a few devices and ensure it works perfectly on those. In reality, if programmed to a basic level, it should run on many more than those specified by us. For branding purposes, it is desirable to have the largest screen size possible something that is not available on the majority of current smartphones.

Our product is pay-for-use, so we can tell our client what hardware they need before they decide to buy. We require clients to have a PDA-type phone with WIFI capability (standard mobile network would be too expensive for the user and not enable us to easily track a device) and finally a screen size of at least 240 x 380 pixels.

From Wikipedia, the free encyclopedia.
“[PDAs] are handheld devices that were originally designed as personal organizers, but became much more versatile over the years. A basic PDA usually includes a clock, date book, address book, task list, memo pad and a simple calculator.”

PDA Software – Operating System (OS)

The 2 main operating systems for PDAs:

  • Windows Mobile 2003 (Microsoft)
    • Cut down version of the Windows operating system
    • Familiar Windows look & feel
  • Palm OS (PalmSource)
    • Developed specifically for PDA use
    • Straightforward to learn and use

Windows have recently released Windows Mobile 5, which contains extra multimedia capability and allows programmers to be more creative when developing new software for mobiles.

There are, of course, others available including Symbian which is an open source project.

PDA Software – Browser

The browser in Windows Mobile 2003 is Pocket IE 2003 (Internet Explorer Mobile for Windows Mobile 5), this supports the following:

This is the browser we will be supporting for the new project – meaning I can code to current web standards.

The only initial worry to me was JScript, Microsoft’s version of ECMAScript, developed originally to compete against Netscape’s JavaScript. Luckily this version does comply with the standards set out by ECMA and is identical to the widely used JavaScript, apart from a few extra features that, yes you guessed it, are not cross-browser compatible. The main features that you are advised not to use (if you want your application to work across different browsers) are:

  • Proprietary COM related features
  • Regular expressions
  • Switch statement (removed from the ECMA standard for simplicity)
  • String manipulation functions

Mobile Release

The PDA version of our application has now been released and we haven’t had any major problems. One area I’d like to expand on is how I decided to layout the pages and when to use different types of controls – but I am going to leave that for a future article.

Update 2006-12-01: Have since left this company so am very unlikely to come back to this post.

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