Opening a “known file type” into running instance of custom app - .NET

Question

How would you open a file (that has a known file/app association in the registry) into a \"running instance\" of the application it\'s supposed to open in? An example would

Answer 1

Windows uses DDE for this purpose.

Dynamic Data Exchange (DDE) is a technology for communication between multiple applications under Microsoft Windows or OS/2.

Registry associations for word or office files usually have DDE commands in addition to the usual file association (to be executed if the app already is running).

So you can host a DDE server in your C# app to implement this functionality.