Palm OS Programming, 2nd Edition

Chapter 5.  Structure of an Application

Before you can write a Palm application, you need to know how it interacts with the OS and how it is organized. Prior to this discussion, we cover the standard terminology and naming conventions within the Palm OS. Once you know what the words mean, we can talk about the application and the OS.

We start with a discussion of how an application is structured to run on the Palm OS. You will learn that a Palm application is an event-driven system and that its routines are structured to handle various types of events. We will describe an application’s life cycle—its starting, running, and closing. To help solidify your understanding of these points, we provide a simple application, OReilly Starter, which is a prototypical Palm application. We walk you through its organization (for example, its source files, utility files, and so on) and then show you the source code in its routines. While the application doesn’t do much, it contains all of the standard routines and has the correct structure for any Palm application. You can use it as the starting point for your own work.

Typically, an application launches when a user opens it; you will learn how to handle this. We will also discuss other times the OS may access an application and what you need to do about it. These instances require you to structure your application so that it can provide information or launch as necessary. Lastly, there are some tricks you might want to add that allow shortcut ...