.net activex在Framework 4.0中不起作用

Question

I have .net usercontrol and I show it in asp.net page as Object. If the target framework of the usercontrol's dll is 3.5 - everything works. If I change it to .net 4.0 - the activex doesn't visible.

The usercontrol is very simple. It's just one button and one label:

[ComVisible(true)]
public partial class UserControl1 : UserControl
{
    public UserControl1()
    {
        InitializeComponent();
        label1.Text = "0";
    }
    private void button1_Click(object sender, EventArgs e)
    {
        label1.Text = Convert.ToInt32(label1.Text) + 1 + "";
    }
}

And this is the html code:

<object id="myControl2" name="myControl2"
    classid="http:ClassLibrary1.dll#ClassLibrary1.UserControl1" 
    width="300" height="350" />
</asp:Content>

Why it's not working?

Answer 1

Hosting controls in IE is now blocked by default (as of v4 or v4.5). See MSDN article under 'Web Applications'.

Fortunately it is super-easy to re-enable the functionality with these reg keys:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework]
"EnableIEHosting"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework]
"EnableIEHosting"=dword:00000001

The x64 key was the one that fixed it for me, running IE8 (x32) on Win7 (x64) using a .Net v3.5 SP1 control compiled for x32.

Answer 2

Windows Forms controls are no longer supported in .NET Version 4 and support for them have been removed.

http://msdn.microsoft.com/en-us/library/vstudio/ee941656(v=vs.100).aspx

* Hosting controls in Internet Explorer *
You can no longer host Windows Forms controls in the Internet Explorer, because there are better solutions for hosting controls on the Web. Therefore, the IEHost.dll and IEExec.exe assemblies have been removed from the .NET Framework.

You can use the following technologies for custom control development in Web applications:

• You can create a Silverlight application and configure it to run outside the browser. For more information, see Out-of-Browser Support.

• You can build a XAML browser application (XBAP) to take advantage of WPF capabilities (requires the .NET Framework on client machines). For more information, see WPF XAML Browser Applications Overview.

Answer 3

This probably is an issue with the security ruleset being applied to assemblies that have been upgraded to .NET 4.

Assemblies that are compiled with earlier versions of the .NET Framework have level 1 transparency. Assemblies that have been upgraded to 4.0 from previous versions have level 2 transparency by default. You can explicitly make them level 1 instead.

Try adding the following to AssemblyInfo.cs :

using System.Security;
// ...
[assembly: SecurityRules(SecurityRuleSet.Level1)]

For more info on the security rule sets please refer to:

• Security-Transparent Code, Level 1
• Security-Transparent Code, Level 2

Answer 4

I have been trying the same and found the following:

You can no longer host Windows Forms controls in the Internet Explorer, because there are better solutions for hosting controls on the Web. Therefore, the IEHost.dll and IEExec.exe assemblies have been removed from the .NET Framework.

from this article: http://msdn.microsoft.com/en-us/library/ee941656.aspx