How to open BusinessObjects Designer XI R3.1 in C#. This is if you add Interop.DesignerX12 as a reference. If you use Interop.Designer, the package namespace is "Designer" not "DesignerX12".

Designer.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DesignerTest
{
    class Program
    {
        static void Main(string[] args)
        {
            DesignerX12.IApplication designer = new DesignerX12.Application();
            DesignerX12.IConnection connection;
            designer.LogonDialog();
            DesignerX12.IUniverse universe = designer.Universes.Open();
            if (universe == null)
                Console.WriteLine("Universe was null");
            designer.Interactive = true;
            connection = designer.Connections.Item[universe.Connection];
            Console.WriteLine(connection.DatabaseSource);
            designer.Quit();
            System.Threading.Thread.Sleep(10000);
        }
    }
}