Interfacing C++ / Java program with a webserver

So, I'm really sorry if this question was already asked or can be easily found, but my main problem here is that I don't even know how to search for what I'm looking for.

The thing goes like this: I want to develop a program that parses a source-code and returns a website, much like PHP. I'm planning on writting it on Java or C++, hence the title. The program itself is the easy part, what I don't know how to do is interfacing said program with, say, the Apache web server (or, more universally, any webserver out there).

The thing should go like this:

• The user goes into http://ift.tt/1UkqXar (let's call my software PQP for the example)

• The webserver, instead of delivering the myfile.pqp file, passes the file to my PQP interpreter and then delivers the output to the user.

Is that possible? How do, for example, Python developed webpages handle that?