Section 1.4. You Got Your Ajax in My Rails

1.4. 'You Got Your Ajax in My Rails!'

We've now looked at what Ajax is and what Rails is. But this book is about both of them together and how these two great tastes complement each other.

As discussed above, one of Rails' mantra is frameworks are extractions. And the story of Ajax in Rails exemplifies that philosophy perfectly. During the development of another 37signals product, TaDa List (http://www.tadalist.com), the developers needed some simple Ajax functionality. Writing the necessary JavaScript for the project turned out to be painfuland pain is often the first sign that an extraction might be useful. By the time the company embarked on its next Ajax/Rails application, Backpack (http://backpackit.com), Ajax functionality had been added to the framework. The result was that Rails was one of the first web frameworks with first-class Ajax support. And because of the philosophy of extraction, it remains one of the most pragmatically useful environments to work in.

There are two sides to the Ajax/Rails coin. The first is composed of two JavaScript frameworks: Prototype and script.aculo.us. Both are bundled with and developed alongside Rails, although they can readily be used with applications in other languages, such as PHP and Java. Prototype provides convenient wrappers around XMLHttpRequest, as well as a wealth of methods for manipulating the DOM and JavaScript data structures. The script.aculo.us library builds atop Prototype and focuses on visual effects and advanced UI capabilities, such as drag and drop.

Rails helpers represent the flip side of the coin. These are Ruby methods, called from within the controller and view code that (among other things) generate bits of JavaScript that in turn invoke Prototype and script.aculo.us. The end result is that it's possible to create very rich "Ajaxified" applications without writing any JavaScript.