The problem is that Esri/Terraformer parser is written in JS and my project is cross-platform C++ on the client side. I've seen this tool and I may be forced to use it in some awkward way if there're no other choices. Also, the main reason for not using Esri C++ libraries is the lack of 64 bit cross-platform support.
Any pointers on how and why the URL query works at all? Is it some kind of an undocumented behavior with Ersi ArcGIS?