For this specific problem I've found a solution. If you want to get the headers from the request that I sent in the question above, you can use php's
get_headers($url) method. It retrieves the headers that I was looking for. I'm really new to protocols and web-services and also to php (1 or 1.5 weeks), therefore I may have asked a silly question and not have been specific enough. Anyways thank you very much for your answers.
Have a nice day!