The growth of Flash and AJAX in Web applications is driven by real market needs - applications that are visually compelling and simple to use gain faster adoption and can be a competitive differentiator, enabling customers, employees, and partners to interact effectively with information and other people. There has been tremendous innovation in applications delivered via the Web; however, browser limitations such as the lack of access to local files, the inability to leverage desktop functionality, and reliance on continuous connectivity ultimately limit the functionality of a browser-based application. In addition, creating these applications is not always a simple process and browser compatibility issues continue to plague front-end developers.

While there are many Web applications that will continue to thrive in the browser, the need for better access to local audio and video assets, and seamless integration between desktop and Web services is driving the next generation of Rich Internet Applications (RIAs). The new RIAs will bring added flexibility and control to developers and engaging application experiences to users by combining the capabilities of desktop applications with the reach of the Web.

A New Class of Applications: RIAs on the Desktop
Adobe is currently working on a project code-named Apollo, which is a new cross-OS, cross-device application runtime to extend the reach of RIAs to the desktop. With Apollo, Web developers will be able to leverage their existing skills in HTML, XML, JavaScript, AJAX, Flash or Flex to build RIAs that break free of browser and platform constraints, allowing them to run on the desktop.

Since Apollo is a cross-platform application runtime, it has little or no visible UI itself, so developers have complete creative control over the application experience they provide to end users. Apollo eliminates cross-browser testing and the need for constant page refreshes, ensuring consistent functionality and interactions across desktops. In addition, Apollo supports seamless online and offline usage, and rich media plays smoothly and reliably. The result is a new class of applications that enhance end-user application experiences without the complexity of traditional desktop development.

End users can interact with applications running on Apollo in the same way that they interact with native desktop applications. Users will go through a familiar install process when placing Apollo applications on their desktops, launch the applications the same way they launch other desktop applications, and uninstall applications in the same way they do today. The end result is that users engage with Apollo applications in the same way as they do with traditional desktop applications, but now they will get a more compelling experience offline as well as online with a rich media application that supports video, audio, HTML, Flash, and PDF.

Of course, not all RIAs need to run outside of a browser on the desktop or integrate tightly with the OS. There will be classes of RIAs that work sufficiently within the browser. Some RIAs may have elements in the browser and on the desktop, and it may make sense for other RIAs to live only outside the browser on a desktop. Going beyond the browser is sensible when developers need to:

• Support users in offline as well as online environments
• Break free of the browser and its chrome
• Establish a closer relationship with the user through often-used applications
• Integrate directly with the desktop to enable capabilities such as drag and drop, clipboard, system tray icons, and file extension registration
• Run applications in the background to bring information to the user

Apollo will provide a set of APIs that can facilitate different capabilities, such as system file access, windowing, background processing, and system tray/toast notifications. These APIs will be accessible within JavaScript and ActionScript (both ECMAScript standard languages) for use by applications running on Apollo. Their capabilities are abstracted so that developers need not worry about the underlying implementation for each operating system. The Apollo runtime will take care of integration with the desktop across all supported operating systems.

By supporting existing Web content and design patterns, developers can reuse many of the same assets and code from their Web-based applications to build applications that run on the desktop. In addition, developers can easily integrate services, such as Flex Data Services for data model synchronization and push and pull notifications, as well as the Flash Media server for bidirectional audio/video.

Adobe authoring tools will be optimized for building Apollo applications. If you are using Dreamweaver to build HTML or AJAX applications for the browser, you will be able to take that Web application to the desktop with Apollo. If you are currently developing browser-based RIAs using Flex Builder and the Flex declarative markup language - MXML - and ActionScript, you can easily extend your Flex applications to the desktop with Apollo. In the future, the same will also be true when using Flash to build applications using ActionScript. If you choose a different tool, you'll be able to leverage the free Apollo SDK, which provides a command-line utility for packaging Apollo applications.

Apollo gives developers a new paradigm that dramatically changes how applications can be created, deployed, and experienced. Developers gain more creative control and can extend their work to the desktop, without needing to learn complex desktop development technologies. Given the tremendous creativity displayed by Web developers worldwide, the opportunities for taking RIAs outside the browser are virtually limitless.

For more information on Apollo and building Apollo applications, visit www.adobe.com/go/apollowiki. To learn more about Flex, visit www.adobe.com/products/flex/. (Figure 1)