How can include .asp file inside of html file and have it proccessed besides having to process all html files with asp.
I'm not totally sure what you're asking. If you're attempting to include a .asp file into a .html file, I don't believe it's possible. If you change your file's extension to .shtml, then you can put the following line into the HTML file:
<!--#include virtual="path to asp file/include-file.asp" -->
Now, whether or not the ASP would be parsed or the code will be displayed will have to be addressed by someone that understands server parsing better than me.
What would be a better solution is to just include an ASP file into another ASP file. If you want functionality like page-including, then giving your files .html or .shtml extensions will only make it harder to accomplish what you're trying.
Basically, use .asp for files that you want parsed and .html for files that can be served up to the user as-is.
you could use an IFRAME tag...but it's a bit sucky. I'd do what Phantom Watson says.
You can change executable extensions, so, if you want, you can make .html executable so that you could include file or do anything else.. Go to IIS manager (run->inetmgr), choose properties of your site, under tab 'Home directory' press 'Configuration..' You can add an extension there and an executable (you can insert the same as in the .asp)
But I don't think this is a best choise :) if it's exetutable, it should be .asp, if it's not - html