how to associate files with application

[Ashok]

hi,
i want to know how to make a specific type of file open in an
application i developed in python when the user clicks on the file.(in
windows) for eg. a .txt file when clicked opens in notepad, a .doc file
when clicked opens in MS-word. In the same way i want to make a .xyz
file open in the application i developed when clicked.
thanks in advance for any advice.