ASP.NET User Control <%@ Register .. > directive confusion

Question

After reading the answer here, I understand that, if I register a user control (I guess I'm really trying to use it as a custom server control) like this:

<%@ Register Assembly="MyDLL" Namespace="MyDLL" TagPrefix="myDLL" %>

Then only the codebehind is used, and the markup (.ascx) page is ignored. Why is this the case (it seems arbitrary), and how can I get around this problem without having to specify the Src="..." attribute in my Register directive? All I want to do is build a user control into a single assembly (a DLL) and hand that DLL off to another web site or web application project in such a way that the web site/app can use my user control. This should not be that hard, but apparently it is...

I am working in Visual Studio 2008, if it makes a difference.

Edit (prompted by the links in Rex's M's comments): it seems like most of the instructions for doing this kind of thing are applicable to VS2005, even the stuff on MSDN. My question is pretty much exactly stated here; is the answer provided on that thread correct

Is there any reliable, recent documentation describing this sort of thing for ASP.NET 3.5 and VS2008? I feel like using the latest versions is causing more confusion and difficulty than benefit.

Answer 1

It sounds like you want the functionality of a Custom Control. In a normal user control situation, the website needs an .ascx and that cannot be placed in a DLL.

Answer 2

I strongly recommend to take a look at custom server controls. Since for the purpose of sharing controls over multiple projects they are better suited in my opinion than user-controls. User controls are better for internal reuse, within the same web application (i.e. on multiple pages).

Answer 3

The thread you linked to is indeed correct. The information which originally addressed .NET 2.0 and VS 2005 is still very applicable. .NET 3.5 does not actually change .NET 2.0, just adds extra stuff. For things that are already in .NET 2.0, they are unchanged in 3.5.