Chapter 9: Writing Applications for Mobile Devices

Overview

Working with Google using a mobile device is a natural extension of the services that Google already provides. In fact, road warriors may well find themselves using a mobile device more often than their desktop machine to search Google. Google recognizes this need and provides access to its service using a specialized mobile interface. You can learn more about this interface at http://www.google.com/options/wireless.html. The two essential problems with this service are that Google supports a limited number of devices (no Pocket PC support) and imposes significant limitations on how you can search. The easiest way to overcome these limitations is to create mobile access for your specific needs using Google Web Services.

Mobile devices do present special problems for the developer, especially a developer using Google Web Services. The biggest problem is what to do with all the data Google returns with every request. Trying to fit all that information on a small screen isn't going to work, so you need to create prioritized displays. The request data presents a smaller problem, but is still something you need to consider. The first section of the chapter discusses the limitations you need to consider in light of the physical and operational characteristics of a mobile device.

It isn't always possible to test your Google Web Services application on the actual machine. Although you should test the application on an actual machine before you give it to anyone , using an emulator can greatly decrease development time and make the development process easier. The second section of the chapter discusses emulators.

Data management is also an issue. Many of the previous chapters of the book discussed scenarios where you can store data locally to improve performance. However, a mobile device doesn't stay in the same place, so using this technique can prove problematic . The third section of the chapter discusses techniques for local and remote data management options.

The remaining sections of the chapter discuss application development techniques for various devices. This chapter uses products such as Visual Studio .NET to show how to access Google Web Services using a mobile device. The mobile device you choose greatly affects the kind of development you perform. For example, a Pocket PC is perfectly capable of running an application locally. On the other hand, smaller devices might require some form of Web access through a custom server setup.

Note  

This chapter uses very specific terms for the various devices. A mobile device refers to any type of device the user can move from one place to another (including PDAs and cellular telephones). A cellular telephone refers to a standard version of this device without built-in intelligence. A Smartphone is a special kind of cellular telephone that includes built-in intelligence that a developer can program using a product such as Visual Studio .NET. A PDA is any kind of non-cellular telephone handheld device. For this book, the term PDA includes both Palm and Pocket PC devices. A Palm device specifically uses the Palm OS. A Pocket PC specifically uses some form of Windows. I won't discuss other PDA OSs in this book.