I was initially baffled when I looked for the Nitro extensions in the current Curl IDE documentation. Then I looked at the source code for the three Nitro samples supplied on the Curl Web site, and that made it clear where to find the Nitro functions in the Curl libraries. One of the Nitro samples did not work for me, however, because of a problem with the Facebook API. The other two samples worked very well.
The Curl RTE (runtime environment) runs on Windows, Mac OS X and four versions of Linux. The Curl IDE runs on Windows and Linux. The Curl development plug-ins for Eclipse work with Eclipse 3.3 and 3.4 on Windows and Linux platforms.
The base Curl IDE and runtime that include Nitro are free, as are deployment licenses for publicly available, free Web sites that use the base capabilities. A Curl Pro/Deployment license starts at US$12,000; Curl has pricing models designed for enterprise, Internet, software-as-a-service and reseller business models.
Google Gears
Google Gears is a free open-source project that adds desktop capabilities to the Internet Explorer, Firefox, Safari and Chrome browsers on the Windows, Windows Mobile, Mac OS X, Linux and Android operating systems. (Chrome has Gears built in and does not need a separate installation.) Currently at Beta Version 0.5 (but ready for prime time now), Gears lets Web applications interact naturally with your desktop; cache and store application resources and blobs ( binary large objects ) locally; store data locally in a fully searchable SQLite database; run JavaScript in the background to improve performance; and perform geolocation both by IP address and by Wi-Fi antenna data.
Basically, Google Gears is a way to take Web applications offline in a browser. Curl Nitro and Adobe Air can go one step farther and dispense with the browser.
Google Gears exposes a JavaScript API to supported browsers. Google hosts the Gears runtime engine, which users must install before running any Gears applications. Developers need to copy gears_init.js into their application directories and call it in order to initialize the Gears factory and APIs; this script will offer to launch the Gears installer if it cannot initialize successfully.
The online Gears developer documentation discusses Version 0.5, released a month ago. It includes nine samples that illustrate the use of the APIs. You can download the source to all of these samples, plus some articles, a couple of tools and an Apache mod implementing the resumable HTTP request proposal. One of the articles is a tutorial on taking Web applications offline with Gears, written by Omar Kilani of Remember The Milk . Kilani and his team implemented offline functionality for their application in "four caffeine-fueled days."