远程桌面ActiveX控件

Question

I've got a C# application that I've been using for years to script remote desktop connections. It's always been built on the AxMsRdpClient3 (note the 3, which I guess is some kind of version number). There are features in AxMsRdpClient8 (version 8) that I want to be able to use, but as I understand it, this requires Remote Desktop version 8 to be installed. Not all users have that installed (or even can install it on Windows XP/Vista), though.

So as Sheng Jiang suggested, I am creating the control at runtime now and I have code that looks like this:

try
{
    AxMsRdpClient8 rdp8 = new AxMsRdpClient8();
    rdp8.BeginInit();
    //  set some properties here
    rdp8.EndInit(); // throws Exception on machines without version 8 installed
}
catch (Exception ex)
{
    AxMsRdpClient3 rdp3 = new AxMsRdpClient3();
    rdp3.BeginInit();
    //  set some properties here
    rdp3.EndInit();
}

As expected, rdp8.EndInit() throws an exception on machines that do not have Remote Desktop version 8 installed. The problem is that after we try to create the AxMSRDPClient8, the rdp3.EndInit() fails as well (class not registered) on older machines. If I don't attempt to create the AxMSRDPClient8 first, the AxMSRDPClient3 initializes and works correctly.

Answer 1

each version of RDP activeX has a different clsid . You need to detect the OS version and create an activex at runtime with the class id corresponding to the lowest OS version you plan to support .

If your code depends on late binding, better rewrite your code to work with IMsRdpClient* and IMsRdpClientNonScriptable*. For example MsRdpClient8NotSafeForScripting supports the following interfaces:

• up to version 8 of IMsRdpClient*
• up to version 5 of IMsRdpClientNonScriptable
• IMsTscNonScriptable
• IMsRdpPreferredRedirectionInfo
• IMsRdpExtendedSettings

MsRdpClient3NotSafeForScripting supports

• version 2 of IMsRdpClient*
• IMsRdpClientNonScriptable
• IMsTscNonScriptable.

if you want to detect whether your activex support a particular interface version, just cast the ActiveX's instance to the interface. when a cast fails you know the interface is not supported.

protected void CreateRdpActiveX()
{
    try
    {
        string clsid=GetRdpActiveXClsIdByOSVersion();
        Type type = Type.GetTypeFromCLSID(clsid, true);
        this.axRdp = new AxHost (type.GUID.ToString());
        ((ISupportInitialize)(axRdp)).BeginInit();
        SuspendLayout();
        this.panel1.Controls.Add(axRdp);     
        ((ISupportInitialize)(axRdp)).EndInit();
        ResumeLayout(false);
        var msRdpClient8 = axRdp.GetOcx() as IMsRdpClient8;
        if(msRdpClient8!=null)
        {
             var advancedSettings9 =msRdpClient8.AdvancedSettings9 as IMsRdpClientAdvancedSettings8;
             if(advancedSettings9!=null) 
                 advancedSettings9.BandwidthDetection=true;

        }
    }
    catch (System.Exception ex)
    {
        System.Console.WriteLine(ex.Message);
    }
}