interface IServer{
    Void GetVersion();
    Void GetCapabilities();
}

interface IPlugin{
    HResult CreatePlugin(IServer server, Iplugin plugin)
}

interface IftpInterface : Iplugin {
    Void Login()
    Void Close()
}

Public Class FtpLibrary  : IftpInterface{
    Void Login();
    Void MakeDir();
    Void Close();

    HResult CreatePlugin(IServer* server, Iplugin* plugin){
        FtpLibrary myFtpLibrary = new FtpLibrary();
        return myFtpLibrary;    //maybe (new FtpLibrary())?
    }
}

static void ReadPluginDirectory()
{
    IFtpInteface iObj = default(IFtpInteface);
    //directory with dlls
    string pluginDir = Application.StartupPath + @"Plugins";
    {
        string[] files = Directory.GetFiles(pluginDir, "*.dll");

        for (int i = 0; i < files.Length; i++)
        {
            try
            {
                //create Assembly class instance.
                Assembly asm = Assembly.LoadFile(files[0]);
                Type[] types = asm.GetTypes();

                foreach (Type type in types)
                {
                    if (type.IsClass &&                (type.FullName== "LibraryFtp.FTPLibrary"))
                    {
                        //classic class instance
                        plugin = (IFtpInteface) asm.CreateInstance(type.FullName);

                        //LibraryFtp return result required method CreatePlugin
                        value = (IFtpInteface)type.InvokeMember("CreatePlugin",
                                                  BindingFlags.InvokeMethod | BindingFlags.Instance |
                                                  BindingFlags.Public, null, plugin,
                                                  new object[] {novyPlugin, novyServer});
                    }
                    iObj = (IFtpInteface)value;

                    {
                        //add value to IList
                        if (iObj != null)
                            pluginy.Add(iObj);
                    }
                }
            }
            catch (Exception e)
            {
                MessageBox.Show("Error reading plugin " + files[i] + ": " + e.Message, "FtpLibrary", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }
    }
}

public static void Main(string[] args)
{
    pluginy = new List<IFtpInteface>();
    ReadPluginDirectory();

    //Vytvoříme si pole rozhraní všech pluginů, abychom jej pohli předat ostatním pluginům.
    IFtpInteface[] plugins = new IFtpInteface[pluginy.Count];

    for (int x = 0; x < pluginy.Count; x++)
    {
        plugins[x] = (IFtpInteface)pluginy[x];
    }

    var ftpClient = plugins[0]; //?????

    try
    {
        ftpClient.Login();
    }
    catch (Exception ex)
    {
        throw new Exception(ex.Message);
    }
}