Rhtml in Ruby, Template Toolkit in Perl, Python’s Django templates, Java’s JSP or Freemarker, and ASP .Net files. All have the same philosophy – render HTML with data streamed from the corresponding web framework ‘controller’ modules.

It’s a great concept – lets you refactor View Templates and come up with ugly looking prototypes quickly. I say ugly since most enterprise programmers tend to have little or no web design skills. Learning effective UI Design is not trivial and asking your programmers to come up with slick UI is a lost cause.

Then you hire Graphic Designers and UI Developers. And your slick RHTML model starts to break horribly.  Web Designers’ tools such as DreamWeaver etc do not understand the server side Templating languages or they understand parts of it. The Web Developer has absolutely no interest in learning the weird syntax And it’s MUCH harder to design and test web pages in Dreamweaver with pages refactored in mutliple files!

When faced with the stalemate, we went back to basics. Separation of concerns!! Divide and Rule. Let two teams work with their favorite tools and we’ll connect the bridge with good old JSON transport. No need to do server side templating, rendering and refactoring. The backend developers had no need to mess around with HTML, CSS, Gifs and PNGs!

So, here’s our setup which keeps everyone happy. For now.

The only connection between Developers( including  Javascript developers) and designers is via <div> IDs. Once those container blocks are placed in HTML pages, the Programmer renders the UI widgets and takes care of AJAX communication with back end.

The Web Designers can continue using Dreamweaver and it’s associated parameterized templates to manage refactoring.

Going pure JSON also means, we can do away with massive rendering Engines in Rails, Merb or other frameworks and work with much simpler Data Delivery Engines which are REST compliant and serve pure JSON. We’ll talk about building such an Engine using Rack in a separate post.

There are number of ajax javascript libraries and frameworkds out there and it can be excruciating to try and find the best fit your projects and organization. A good library should encapsulate most often used patterns and provide clear and easy to use abstractions. No library, however mature, can be complete, since it’s always possible to find that one most important piece of missing functionality that you need. So, extensionability is a major requirement.

Javascript is an awesome language. It’s super flexible. It empowers the developer with immense flexibility. You can use the power to advance world peace or choose to shoot yourself. It’s totally upto you. As spiderman said – with power comes responsibility. Since there are no private namespaces in Javascript, it’s ultra important that the library you choose NEVER dirties your namespace and lives completely inside it’s own namespace. One of the most popular javascript library – prototype.js – violates this principle completely and IMHO, should be used with care.

Javascript started in Browsers and even today it’s most often found in the browsers. Browsers are the modern UI paradigm. The javascript library must not be limited to cookie-cutter DOM manipulation APIs. That was cool in the 90s. The Libraries now must provide a rich set of UI Widgets. You don’t want to be using two Javascript libraries – one for Ajax and other for UI widgets.

Documentation. If the developer has to resort to ‘grep’ the source code to find essential pieces of functionality, the library becomes a time hog instead of rapid development platform!

We looked at quite a few js libraries :

* JQuery
* Qooxdoo
* Dojo
* Prototype.js
* mootools
* extjs

and settled for extjs as our framework of choice.

Here are our reasons for picking a commercial open source library like extjs.
The overall design of extjs is exemplary. One can learn a lot from it’s unified architecture – no matter which language one is programming in.

It lives within it’s own namespace. Prototype.js was out at this point.

The UI widget set is extremely rich. Dojo, qooxdoo and mootools – although promising, were nowhere close to extjs in widgets collection. Although jquery , with it’s collection of opensource plugins, has a rich collection, it suffers from one major disadvantage. The plugins are from multiple vendors and there is no consistent Object model to dictate their design. Extjs requires you to start with one of their base classes – ensuring a consitent model. Consistency is extremely important for the library to be reusable.

Not to mention, extjs documentation seems to be very comprehensive and well maintained. In a library as comprehensive as extjs, one should always be prepared to look into the source code to fund missing bits but all essential pieces are very well documented.

Many people seem to object to commercial licencing of extjs – however, we believe, the licencing is quite fair and inexpensive. A single developer licence costs less than $300 and one can deploy on unlimited domains. You can develop your application for free and purchase a licence when you go live. For most businesses this shouldn’t be an issue at all.
On the other hand, if your business can’t come up with $300.00, you’ve bigger issues and shouldn’t be worried about javascript libraries !!