Third-party integrations are the worst. To top it all if the company is working on PHP5 and expects API requests/responses in XML is recipe for disaster.
Old companies running code and standards older than a decade should just die and shut shop.

The tech support expects me to send a response in an exact format for unauthorized requests as well. Asked him why are you testing format for unauthorized code, he had no answer.

It's called soap.
It's been around longer then php5.

Also, xml in php is simple as simple_xml 😉

the tcp/ip stack is in its 30s whats the replacement?

And I was asked by a client to generate XLS instead of XLSX. Ofcause my answer was “This is technically impossible for us to do”. Which is partly true : can’t use interop from Azure webservice. I guess I could find a 3d party library, but, man, fuck 1997 file format.

New doesn't mean better.