What can it do?

Silverline can run Ruby on the client because of Silverlight, the 4 megabyte download of the .NET Framework, and IronRuby, the implementation of Ruby on .NET and the Dynamic Language Runtime. Silverline lets you do anything you can do in Silverlight with IronRuby you can do from Rails, but a whole lot easier.

Silverlight applications can use HTML and vector graphics with WPF (either through code or XAML markup for rendering their UI; silverline integrates this capability into Rails by enabling Ruby and XAML partials.

Easier from Rails

Ruby partials can even use RJS, so simply renaming foo.rjs to foo.rb will avoid the server-side JavaScript generation and actually runfoo.rb on the client. XAML partials give you the ability to render XAML without having to bootstrap Silverlight yourself. XAML partials can also be passed through ERb for server-side or client-side processing.

Experimental

Note: the following is still a work-in-progress; your feedback is appreciated:

Silverline also lets you run pieces of your Rails application on the client, removing the need to write a separate JavaScript or Flash application simply to move functionality to the client. This is accomplished by flagging certain actions as "client", and running the necessary pieces of your Rails appliation and Rails itself on IronRuby in the browser.

You can also decorate ActiveRecord models with "acts_as_client" so any calls to ActiveRecord on the client get translated into ActiveResource calls to a restful API on the ActiveRecord model that was decorated.