Check this link.
Mendix has a module for dealing with REST webserivces in the app store. If you add this module to your project, most REST webservices become easy to implement. The only drawback is that the module is not out of the box ready to deal with string array mapping. But most REST webservices do not have this.
The documentation for implementing this can be found in the link below: https://github.com/mendix/RESTServices#sending-and-receiving-files