Palm webOS

Chapter 2. Application Basics

Palm webOS provides a great environment for building applications. The use of standard web development languages and tools, combined with access to native services and local data gives you a powerful and productive platform. Even Java and C/C++ developers will find that building applications using dynamic languages on webOS is fun and exciting. And despite what you might have heard, you can build real applications, not just web gadgets and spinners.

A browser-based web application is really just a set of complex web pages. They are downloaded from a web server and present their UIs as HTML, often with JavaScript as a client-side language to validate input, animate page elements, and make background Ajax calls back to the web server for additional interactivity.

If you are a developer writing these web applications, the Palm webOS development environment will feel familiar. JavaScript library code generates the HTML UI, interacts with page elements, and issues Ajax calls to web servers. You can style the UI with CSS, either to make your application look and feel consistent with Palm’s style guidelines or to make your own unique look.

The programming model is a little different. Since the HTML is not generated on a server (say, using Java, PHP, or Ruby), there is no request/response lifecycle. Instead, all of your application code is in JavaScript—even interactions with key webOS systems (UI widgets, location services, and other applications) are made with ...