I had a chance to play with Google Gears on a mockup project recently. I was surprised to learn that my understanding of Gears was not the same as the reality of Gears. I had expected it to be a JS library to facilitate rich HTML applications to handle spotty network connections. It turned out that Gears is a browser plugin that adds useful tools that any rich web app developer would find useful, though they are all aligned to handle an app losing its network connection. In the two days that I spent playing with Gears, I was pretty much blown away by the power and simplicity of it.
- A cross-browser compatible XMLHttpRequest
- Local database storage
- A web resource cache, so that items can still be fetched even if the network connection goes down. This is nearly completely transparent to the developer, and works for resources loaded by Gears or by the browser itself.
- A mechanism to run scripts in the background (for real).
And that's it. There's more to Gears that what I described (though not much more). It also includes some geolocation bits (presumably for Android, and maybe Safari Mobile, integration), desktop integration stuff, a standards-compliant timer, a file multi-chooser (yay!), and a binary data type (as opposed to String, which is for textual content). It's a shame that Gears is still in beta. I would really like to see some sites that use it. Of course, since I just recently installed Gears, there might be some sites that do and I never realized it.