**Synopsis (in case you don’t want to read my story below) :: If you’re running CF9 and .Net Framework 4 and getting an error that indicates that the given class cannot be found in the given assembly it is likely that you need to upgrade your Coldfusion to 9.01 and restart both CF and .Net services.

I’ve been doing some ongoing research lately concerning the ability of CF to execute .Net classes. I’m running CF9 and .Net Framework 4. I began by calling the built-in .Net method GetHostName() that simply returns a string of basically the computer name.

Calling a Built-In .Net Class

<cfobject type=".NET" name="variables.test" class="System.Net.Dns" action="create" />
<cfset variables.hostName = variables.test.GetHostName() />
<cfoutput>
	#variables.hostName#
</cfoutput>

Worked perfect. What a great start! I’ve essentially just executed a .Net method with Coldfusion in less lines of code than I could have done writing a C# class. Excellent. So at this point I thought it was time to execute a class written and compiled by myself. I can’t remember my exact test, but it was something very simple that just returned a string like the following.

Simple C# Class

namespace testClass
{
    public class Test
    {
        public String returnName()
        {
           return "Matt";
        }
    }
}

I compiled the class into a .dll and saved it to somewhere easy to get to like the desktop. I then wrote a similar cfobject tag to call this like the following.

Coldfusion Caller

<cfset variables.pathToDll = "/Desktop/classLibrary/myClass.dll" />

<cfobject 	type = ".NET"
			name = "variables.test"
			protocol = "tcp"
			class = "testClass.Test"
			assembly = "#variables.pathToDll#"
			action = "create"
			secure = "false" />

Executing this code returned an error indicating that the class ‘Test’ could not be found in the selected Assembly. This was good news and bad news. The good news was that it found my Assembly. The bad news, obviously it couldn’t find the class.

After several hours of trying things and research I finally found that the .Net Framework 4 support was introduced in the CF9 Update 1. A quick check revealed that I was indeed not running 9.01. I upgraded, restarted both CF and .Net services and everything worked!