Palm webOS, now owned by HP since it bought Palm for $1.2 billion earlier this year, integrates a window-based operating system with the simplicity of a browser. Most applications are built using standard Web technologies and languages (HTML, CSS and JavaScript) and can leverage device-based services and data.

Beyond the Linux-based operating system, webOS includes a number of core applications: contacts, calendar, tasks, memos, phone, browser, email and messaging. Other applications were included in the initial release, such as a camera, photo viewer, audio/video player and map application, but the full application suite for a given webOS device will vary depending on the model and carrier configuration.

Applications are run within UI System Manager, an application runtime built on standard browser technology, to render the display, assist with events, and handle JavaScript.

The webOS APIs are delivered as a JavaScript framework called Mojo, which supports common application-level functions, UI widgets, access to built-in applications and their data, and native services.

Mojo Application Framework

Through Palm’s Mojo application framework, applications can embed user interface (UI) widgets with sophisticated editing, navigation and display features, enabling more sophisticated application UIs. The framework also includes event handling, notification services and a multi-tasking model. Applications can run in the background, managing data, events and services behind the scenes and engaging the user when needed.

Palm WebOS SDK

The webOS SDK includes the development tools, sample code, the Mojo framework, along with access to the Palm Developer Wiki, where developers can find various training materials, tutorials and reference documentation. The kit is available at Palm’s developer site.

From the SDK, developers install Palm Developer Tools (PDT), which include targets for Linux, Windows (XP/Vista) and Mac OS X. The tools allow developers to create a Palm project using sample code and framework defaults, search reference documentation, debug their apps in the webOS emulator or an attached Palm device, and publish an application.

Here are the main tools in the PDT:

• SDK Bundle Installer — Installs all webOS tools and SDK for third-party editors
• Emulator — Provides Desktop Emulator and Device Manager
• Command-Line Tools — Enable creating new project; installing and launching in Desktop Emulator or Device Manager; opening Inspector/Debugger window; and packaging and signing apps

The tools can be installed and accessed as command-line tools on every platform. They also include some bundles for integration into popular HTML editors and can be used as plugins to Eclipse and Aptana Studio, a popular JavaScript/HTML/CSS editor for Eclipse.

Languages Supported on WebOS

WebOS supports multiple languages. Typically, applications are written in JavaScript, HTML, Ajax, and other common Web technologies handled by WebKit, as well as in C and C++.

Devices Running WebOS

HP has promised to maintain webOS and leverage the platform into multiple products, including smartphones, HP slate tablets, and printers.

Devices currently running webOS include the Palm Pre and the Palm Pixi on Sprint, as well as the Plus version running on Verizon Wireless, AT&T and some international carriers.

WebOS Costs

At the time of writing, HP was offering a limited-time offer to waive its $99 annual fee to developers who want to open a developer account, which includes community membership and developers to distribute webOS apps and manage them online.

WebOS Documentation and Developer Support

Developers can find plenty of support and information at developer.palm.com. This portal provides access to everything that a developer might need to build webOS applications, including access to the SDK, all development tools, and documentation and training materials.

The site also provides application-signing services and access to the Application Catalog, an app store that is published and promoted with every webOS device.

WebOS Pros and Cons