Datasheet

❑ Because ASP.NET is based on the common language runtime (CLR) and .NET, ASP.NET does

not suffer from the versioning problems of COM. The .NET framework allows for multiple

versions of components to be on a system without their interacting with each other.

❑ ASP.NET is compiled. The first time that a file is loaded, it is compiled and then processed. The

compiled file is then saved into a temporary directory. Subsequent calls to the ASP.NET file are

processed from the compiled file. The execution of the compiled file on requests is faster than

the interpreted environment of classic ASP.

All in all, ASP.NET is a dramatic improvement over ASP and has become widely accepted in the devel-

opment community.

So, What’s the Problem?

Based on what you have just read regarding ASP.NET, it may sound really good to you. You may be asking

yourself, “Why is there a need for something else? What’s the problem?”

The truth is that ASP.NET has several issues that need to be addressed:

❑ Round trips — The server events in ASP.NET require round trips to the server to process these

events. These round trips result in all form elements being sent between client and server as

well as images and other data files being sent back to the client from the server. Though some

web browsers will cache images, there can still be significant data transfer.

❑ Speed/network data transfer — Because of the

ViewState hidden form element, the amount of

data that is transferred during a postback is relatively large. The more data and controls on the

page, the larger the

ViewState will be and the more data that must be processed on the server

and transmitted back to the client.

❑ Waiting on the result — When a user clicks a button or some other visual element that posts

back data to the server, the user must wait for a full round trip to complete. This takes time

when the processing is done on the server and all the data, including images and

ViewState,

are returned to the client. During that time, even if the user attempts to do something with the

user interface, that action is not actually processed on the client.

❑ User context — Unless an application is able to properly use the

SMARTNAVIGATION feature of

ASP.NET, the user is redirected to the top of a page by default on a postback. Though there are

ways around this issue, this is the default behavior.

❑ Processing — The number of server round trips, amount of data that is transferred, and the

ViewState element’s size result in processing on the server that is not really necessary.

Users typically do something, data is sent to the server, the web server processes it, and the result is

finally sent to back to the user. While the server is processing the data, the user interface is “locked”

so that additional operations don’t happen until a result is returned to the user.

Chapter 1: Introduction to ASP.NET AJAX

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