Question

I am a beginner to .NET, I have some doubts in my mind. Can anybody help me to sort out?

1. When a user requests for a file(*.ASPX), The request first goes to IIS server and with the help of Handlers and modules it finds the type of file that need to be processed and sent back to the client. But while displaying on the cilent machine the content of the .ASPX file will be displayed as HTML controls. How are the events generated at the client side and sent back to the server?

2. I know runat=server tells the control will be processed at serverside.
   But every time why we need to write “runat=server”. Is there any ASP.NET control which runs at client side?

Answer 1

if you are starting with .NET web development, ASP.NET MVC is the way to go IMO

an ASP.NET server control that is generating client events in the browser is exercising standard dom events via javascript code that gets injected into the page that is sent from the web server. try view page source from any browser to see what is actually generated and the picture will become more clear.

essentially runat=server is telling the ASP.NET parser to process the tag and generate some special HTML output for the page. see GvS’s explanation in this thread of how client events for these controls are converted to a form POST that is handled on the server.

http://www.w3schools.com/aspnet/aspnet_intro.asp

How Does ASP.NET Work?

When a browser requests an HTML file, the server returns the file When
a browser requests an ASP.NET file, IIS passes the request to the
ASP.NET engine on the server The ASP.NET engine reads the file, line
by line, and executes the scripts in the file Finally, the ASP.NET
file is returned to the browser as plain HTML

also see

http://www.w3schools.com/aspnet/aspnet_controls.asp

http://www.w3schools.com/aspnet/aspnet_events.asp