Aside from using a different scripting language, it seems that the main appeal of node.js is it’s support for event-driven programming which makes it easier to write scalable servers (or other typically I/O bound applications) due to its simplified non-blocking I/O calls. However, this feature comes at the expense of having to learn a new programming model which essentially requires you to pass callback after callback function making some straightforward tasks (e.g. dependent sequences of actions) a bit more complicated.
Contrast that programming model to the traditional one of Ruby on Rails which blocks on all I/O operations and is (effectively) single-threaded (due to MRI’s green thread implementation).
Just dreaming out loud here, it seems that it should be possible to implement a Ruby (or Rails) runtime which reconciles these models by trapping I/O calls, transparently replacing them with their non-blocking version, storing the current continuation and calling it when the I/O operation is complete. This way you would get the familiar, procedural programming style and the benefits of the event-driven/asynchronous/callback model.
Is such a runtime (or runtime translator) technically possible? Are there web frameworks that do something like this already?
Thanks to @igorw, the async-rails project is what I was imagining.
But as @Raynos and @apneadiving point out, there are potentially better solutions such as Ruby EventMachine and stormjs.