Our team originally consisted of mostly server side developers with minimum expertise in Javascript. In ASP.NET we used to write a lot of UI logic in code-behind or more recently through controllers in MVC.

A little while ago 2 high level client side developers joined our team. They can do in HTMl/CSS/Javascript pretty much anything that we could previously do with server-side code and server-side web controls:

• Show/hide controls
• Do validation
• Control AJAX refreshing

So I started to think that maybe it would be more efficient to just create a high level API around our business logic, kinda like Amazon Fulfillment API: http://docs.amazonwebservices.com/fws/latest/APIReference/, so that client side developers would fully take over the UI, while server side developers would only concentrate on business logic.

So for ordering system you would have a high level API like:

OrderService.asmx

CreateOrderResponse CreateOrder(CreateOrderRequest)
AddOrderItem
AddPayment
-
SubmitPayment
-
GetOrderByID
FindOrdersByCriteria
...

There would be JSON/REST access to API, so it would be easy to consume from client-side UI. We could use this API for both internal UI development and also for 3-rd parties to create their own applications.

With advances in Javascript and availability of good client side developers, is it a good time to get rid of code-behind/controllers and just concentrate on developing high level APIs (ala Amazon) that client side developers can consume?