Getting C# to recognize a dll outside of Visual Studio

Question

Several years before I started working at this job another developer who is no longer here wrote an application in classic ASP using HTML, vbscript and javascript. This is fine but the problem is that 2 pages were written in C# with an HTML file and a code behind file. There was no solution files for these two pages. They may have been originally created in Visual Studio but they don't exist in it now.

That is important because there is a lot of things that Visual Studio just does for you without even thinking.

My problem is that in these two C# pages I need to get them to reference a DLL. This is a simple task when using Visual Studio. You just add a reference to the project and life is good. But outside of VS nothing seems to work.

I tried putting the dll in the same folder as the pages and then I tried the following:

• Using myDLL;
• myDLL dll = new myDLL();
• myDLL dll = myDLL();

I found some code online that said to create an internal static class and use [DLLImport()] but that didn't work either. It couldn't find the dll or the Entry Point for the dll. I am currently researching how to create an entry point, just in case this is the method to make everything work.

Outside of having to rewrite these pages in vbscript (which I don't have the time to do) I am at a loss.

Has anyone ran into this problem before? Is there something that I can put in the web.Config? Or is this just impossible and I am hosed.

BTW this is all running under the 2.0 .net framework.

Answer 1

I created a VS Solution/Project for my app. I compiled and published it to the web server. When I published it I had it copy all project files.

I ran it and it crashed because it could not find my dll.

I tried adding the lines that Andras mentioned above and it seemed like it was getting me closer but it only changed the errors I was getting.

Then I went into IIS on the web server. I expanded the folder listing under Web Site. I right clicked on the folder that contained my app and made that folder into an application folder.

After I did that everything just worked. So then I thought I would see what happened if I backed out all of the additional code I added to my C# app and the Web.Config file. It still worked. All I needed to do was to make the folder an application folder in IIS and put a Using statement in my C# app and life is wonderful again.

Thanks for all the comments and suggestion. Andras thanks for the link to ILSpy. That is a cool little tool.

Take care, Robert

Answer 2

If you drop the DLL you want the code to reference into the bin folder of the website, then open the web.config and locate the following section configuration -> system.web -> compilation -> assemblies.

You need to add the display name of the assembly to that list - so that the compiler will reference that assembly during it's late-bound build process.

Now you should be able to use the stuff that's in it on those pages.

If you don't the know the display name of the assembly (typically yourassembly, version=*.*.*.*, Culture=neutral, PublicKeyToken=null for culture-invariant, non-strong-named assemblies) you can open it in a tool like ILSpy (there are others, it's just become my favourite) and it tells you when you select it in it's UI:

sorry for the poor highlighting - jerky hand following far too much coffee

If all the code in that assembly is in a single namespace, also, you can also add a default using to all the .cs or .aspx code in the project by adding that namespace to configuration -> system.web -> pages -> namespaces - making it simpler to use that code in the pages.

Answer 3

I agree with Jon, it sounds like you should try creating a new project for these files. It's always better to leave code better off than you found it. If a new project is not an option for some reason, you should indicate this in your question.