Internet Information Services (IIS)

Dear Siemens Support and Forum,

I have a question in general to the WinCC Unified Systems: what is the Internet Infromation Services (IIS) is used for exactly ? Is there a specific list about the features what requires IIS?

I raised the question because I would like to run Unified Systems on a PC what host an Apache webserver provided by xampp. Obiviously the http and https ports are colliding. Since the Apache webserver items are used widely in the system I don't want to change the ports of it. I have changed the port numbers in the IIS, the main page was working fine however the WebRH doesn't.

Finally, I could ask my question in the following way: what will I lose if I stop the IIS running? Obivously I cannot run a localhost device (WinCC Unified PC RT) on the development PC, but is there anything else what might not work?

I also wonder that why is it not possible to control and change ports directly from TIA portal or why is it forced via the IIS in every case to block the local http and https ports if only used for the WinCC Unified PC RT...

Thanks