Omar AL Zabir blog on ASP.NET Ajax and .NET 3.5

ASP.NET MVC Controllers can directly return objects and collections, without rendering a view, which makes it quite appealing for creating REST like API. The nice extensionless Url provided by MVC makes it handy to build REST services, which means you can create APIs with smart Url like "something.com/API/User/GetUserList"

It's a good practice to use many small Javascript and CSS files instead of one large Javascript/CSS file for better code maintainability, but bad in terms of website performance. Although you should write your Javascript code in small files and break large CSS files into small chunks but when browser requests those javascript and css files, it makes one Http request per file. Every Http Request results in a network roundtrip form your browser to the server and the delay in reaching the server and coming back to the browser is called latency. So, if you have four javascripts and three css files loaded by a page, you are wasting time in seven network roundtrips. Within USA, latency is average 70ms. So, you waste 7x70 = 490ms, about half a second of delay. Outside USA, average latency is around 200ms. So, that means 1400ms of waiting. Browser cannot show the page properly until Css and Javascripts are fully loaded. So, the more latency you have, the slower page loads.

Generally we put static content (images, css, js) of our website inside the same web project. Thus they get downloaded from the same domain like www.dropthings.com. There are three problems in this approach:

Last week I released a new version of Dropthings, my open source AJAX portal, that shows many fancy Web 2.0 features and showcases extensive use of ASP.NET 3.5, Workflow Foundation, C# 3.0 new language features, custom ASP.NET AJAX extenders, many performance and scalability techniques. I have written a book on these topics as well.

There are several problems with ASP.NET MVC application when deployed on IIS 6.0:

UFrame combines the goodness of UpdatePanel and IFRAME in a cross browser and cross platform solution. It allows a DIV to behave like an IFRAME loading content from any page either static or dynamic. It can load pages having both inline and external Javascript and CSS, just like an IFRAME. But unlike IFRAME, it loads the content within the main document and you can put any number of UFrame on your page without slowing down the browser. It supports ASP.NET postback nicely and you can have DataGrid or any other complex ASP.NET control within a UFrame. UFrame works perfectly with ASP.NET MVC making it an replacement for UpdatePanel. Best of all, UFrame is implemented 100% in Javascript making it a cross platform solution. As a result, you can use UFrame on ASP.NET, PHP, JSP or any other platform.

A web page can load a lot faster and feel faster if the javascripts on the page can be loaded after the visible content has been loaded and multiple javascripts can be batched into one download. Browsers download one external script at a time and sometimes pause rendering while a script is being downloaded and executed. This makes web pages load and render slow when there are multiple javascripts on the page. For every javascript reference, browser stops downloading and processing of any other content on the page and some browsers (like IE6) pause rendering while it processes the javascript. This gives a slow loading experience and the web page kind of gets 'stuck' frequently. As a result, a web page can only load fast when there are small number of external scripts on the page and the scripts are loaded after the visible content of the page has loaded.