How do I share user controls between web applications in ASP.NET?

This question is a follow up to my question about sharing resources between web applications, because I have not yet found a good solution.

I have a web application with user controls and resources that are shared by three other web applications.

Solution
|
+-CommonControlsWebApp
| +- resources
| |  +- images
| |  +- scripts
| |  +- stylesheets
| +- UserControls
| 
+-WebApp1
| 
+-WebApp2
| 
+-WebApp3

This is what I know this far:

• I can not compile CommonControlsWebApp into a single dll since I am creating user controls. This is only possible with custom server controls, where everything is in the code-behind file. So I need a way to share the ascx files between the four projects.
• Copying the files from CommonControlsWebApp into the three other projects does not update their files in the solution explorer. I would have to 'add exting items' all in all three WebApps when a file is added or renamed in CommonControls.
• Changing to the Web Site model would remedy this, but I am worried about the compile time for WebApp1-3 if I do this.
• 'Add as link' does not work for directories.
• I could use Subversion to share the files between the projects, but i believe that this would require me to check the files in and out again all the time if I am developing a user control that I have to test through one of the WebApps.

Can it really be true that ASP.NET does not have a good solution for this? How are you guys organizing large web applications?

Edit: Thanks a lot for all the answers. I am going to copy my user controls with a build event for now, and then see if we have time to refactor them into server controls.

From stackoverflow

• One option is to try "Add existing" and in the dialog that appears, the OK button has a drop arrow next to it, change it to Add with a link.

  If that doesn't work, rewrite your controls as Custom Controls.

  It will take a little while, but will make it much more maintainable in the future.

• In order to share controls between web apps, the only way I found was to either rewrite them into server controls or to use virtual directory to make the user controls actually in folder be in each project.

  Unfortunately, asp.net doesn't really have a good solution for this. The same is true for sharing master pages.

• hey this is not the best way to do things but i used to do this in my asp.net 1.1 days - you can try this - shift your user controls into a seperate project, and publish this project as a virtual directory under iis

  as long as you are not using codebehind - your updates would be cool (only update shared user control folder)

  if you do use codebehinds - redeploy the user control dlls into different projects

  ---

  once you are done with this - map these user controls into all projects using their virtual paths

  check these links - http://aspadvice.com/blogs/ssmith/archive/2006/10/05/Tip_3A00_-Share-User-Controls-Between-Applications-in-ASP.NET.aspx

  AND

  http://www.123aspx.com/redir.aspx?res=30887

• The way we do it at my present company is to make sure CommonControlsWebApp is a WebApplication, not a web site. Then you use names for the folders that would help identify it as the common ones that are distinct from the individual web apps. (CommonUserControls instead of just UserControls)

  In your other web apps, you create a virtual directory to the CommonUserControls, etc, and add a file based reference to the CommonControlsWebApp.dll

  This requires you to use IIS for development (not casini), and Visual Studio won't believe that the controls really exist, but it will work at runtime, and you can build just fine with only warnings about blahblah.ascx or blahblah.master path invalid.

  If you do use common master pages and Visual Studio 2008, you will need SP1 for 2008 and use a __fallback.master in the root of the individual web projects to go in to design mode.

  However, I saw this on another thread, and I am going to look into doing more like this: http://webproject.scottgu.com/CSharp/UserControls/UserControls.aspx

  annakata : using IIS for development over cassini is a *good thing*

• You might consider using source control and sharing your controls at that level. We do this for a sizable user control library and it works quite well.

  Using SourceGear Vault but you should be able to do this with any source control product.

  Jan Aagaard : But won't this require me to commit any changes made in the library to make them available in the other projects?

  Andrew Robinson : Yes. They are either shared across projects or they are copied. Can't have it both ways.

  Andrew Robinson : If you don't want them all shared, they have a "shared controls" folder and a (non-shared) "controls" folder.

• Check this post for how to solve this issue.

  The basic idea is to change your project to have a prebuild step to copy over the .ascx files to a subdirectory of the web application. Then just refer to those copies when using them. Of course you also need to reference the UserControls assembly as well.

• You could compile it into a dll

  Turning an .ascx User Control into a Redistributable Custom Control

  Brief Outline of the Steps

  The basic steps to make this happen are as follows:

  1. Write your user control as you normally would, typically using the Visual Studio designer.
  2. Test it using a simple page before trying to deploy it.
  3. Deploy the application to precompile it.
  4. Grab the user control's assembly produced by the deployment step, and you're essentially done: You have your custom control.
  5. Finally, use your custom control in other apps

  Further info here http://www.nathanblevins.com/Articles/Compile-a-Web-User-Control-into-a-DLL-.Net-c-.aspx

  Jan Aagaard : Thanks a lot for the links.