Derby is one of a new breed of JavaScript frameworks that take advantage of the interesting NodeJS to create a web app framework that runs your code both on the client and the server.  This has a tonne of huge advantages compared to writing a complex JavaScript application that has to communicate with a different language on the server and still maintain visibility to Google.  The big advantages I see from this:

• Only one language to work in makes it easier for developers
• Communcation between client and server is automatic and seemless
• Pre-rendered on the server, updated on the client so Google gets the proper content but you still get dynamic updating for your users

So with this in mind I decided to do a little test app and of course the first step was getting it installed.  These are the steps I had to go through to get it working.

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:chris-lea/node.js
sudo apt-get update
sudo apt-get install nodejs npm
sudo npm install -g derby

So far so good, you create and start-up your app like this…

derby new first-project
cd first-project
npm start

Happ coding and lets hope these frameworks make creating fantastic, dynamic apps a breeze in the future!

Oh, for an alternative try.. [meteor][2].

[2]: http://www.meteor.com/