How do I run a Python Script in a Java web application?

I'm new to programming and I need to run a Python script (write input and read output) inside my Java application that will eventually be uploaded onto the web. How do I do this such that it is compatible across all platforms? I've tried things like Jython and Runtime.exec() in Java and I think both require Python to be installed on the computer (correct me if I'm wrong) but I want the app to be freely available to anyone who uses it on the web.

FYI the Python script imports win32com.client to operate on a COM object.