using registered com object dll from .NET

Question

I implemented a python com server and generate an executable and dll using py2exe tool. then I used regsvr32.exe to register the dll.I got a message that the registration was successful. Then I tried to add reference to that dll in .NET. I browsed to the dll location and select it, but I got an error message box that says: A reference to the dll could not be added, please make sure that the file is accessible and that it is a valid assembly or COM component.The code of the server and setup script is added below. I want to mention that I can run the server as a python script and consume it from .net using late binding. Is there something I'm missing or doing wrong? I would appreciate any help.

thanks, Sarah

hello.py

import pythoncom

import sys

class HelloWorld:

    #pythoncom.frozen = 1
    if hasattr(sys, 'importers'):
        _reg_class_spec_ = "__main__.HelloWorld" 
    _reg_clsctx_ = pythoncom.CLSCTX_LOCAL_SERVER
    _reg_clsid_ = pythoncom.CreateGuid()
    _reg_desc_ = "Python Test COM Server"
    _reg_progid_ = "Python.TestServer"
    _public_methods_ = ['Hello']
    _public_attrs_ = ['softspace', 'noCalls']
    _readonly_attrs_ = ['noCalls']

    def __init__(self):
        self.softspace = 1
        self.noCalls = 0

    def Hello(self, who):
        self.noCalls = self.noCalls + 1
        # insert "softspace" number of spaces
        print "Hello" + " " * self.softspace + str(who)
        return "Hello" + " " * self.softspace + str(who)


if __name__=='__main__':
    import sys
    if hasattr(sys, 'importers'):

        # running as packed executable.

        if '--register' in sys.argv[1:] or '--unregister' in sys.argv[1:]:

            # --register and --unregister work as usual
            import win32com.server.register
            win32com.server.register.UseCommandLine(HelloWorld)
        else:

            # start the server.
            from win32com.server import localserver
            localserver.main()
    else:

        import win32com.server.register
        win32com.server.register.UseCommandLine(HelloWorld) 

setup.py

from distutils.core import setup
import py2exe

setup(com_server = ["hello"])

Answer 1

I will answer my question to help any one may have similar questions. I hope that would help. I can not find my server on the COM tab because, .NET (& Visual-Studio) need COM servers with TLB. But Python's COM servers have no TLB. So to use the server from .NET by (C# and Late binding). The following code shows how to make this:

// the C# code

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Reflection;

namespace ConsoleApplication2

{

    class Program

    {
        static void Main(string[] args)

        {

              Type pythonServer;
              object pythonObject;
              pythonServer = Type.GetTypeFromProgID("PythonDemos.Utilities");
              pythonObject = Activator.CreateInstance(pythonServer);

        }
    }
}   `

Answer 2

The line:

_reg_clsid_ = pythoncom.CreateGuid()

creates a new GUID everytime this file is called. You can create a GUID on the command line:

C:\>python -c "import pythoncom; print pythoncom.CreateGuid()"
{C86B66C2-408E-46EA-845E-71626F94D965}

and then change your line:

_reg_clsid_ = "{C86B66C2-408E-46EA-845E-71626F94D965}"

After making this change, I was able to run your code and test it with the following VBScript:

Set obj = CreateObject("Python.TestServer")   
MsgBox obj.Hello("foo")

I don't have MSVC handy to see if this fixes the "add reference" problem.

Answer 3

If you want to use a registered Com object, you need to find it on the Com tab in the Add Reference dialog box. You do not navigate to the dll.