Question

I used DLLImport[absolute path of the C++ dll] in my asp.net C# code to call a method that is inside a C++ dll. And that works perfectly.

I then published the website on IIS and it says it cannot load the dll.

Can you please suggest how to resolve this issue?

Answer 1

I use a Native LoadLibrary to load the DLL from a specific location. The below URL talks about how this can be done.

I am assuming you have the right permission set’s available to work with unmanaged code, you use something on the lines of:

private static bool CanCallUnmanagedCode
{
 get
  {
  try
  {
    new SecurityPermission(SecurityPermissionFlag.Unmanage dCode).Demand();
  }
  catch(SecurityException)
  {
    return false;
  }
  return true;
 }
}

void Page_Load(Object sender, EventArgs e)
{
  if (CanCallUnmanagedCode)
    Label1.Text = "This page can call unmanaged code.";
else
    Label1.Text = "This page can NOT call unmanaged code.";
}

Where Label1 is :

<asp:Label id="Label1" Text="Label Control" runat="server"/>

Next thing is to check the bitness of you asp.net environment to ensure it matches you .dll… as x86 DLL cannot be loaded via a x64 environment.

How to call C++ DLL from ASP.NET (C#) code?

http://msdn.microsoft.com/en-us/library/ms684175