I wouldn't think this is specifically a “qcodo-way” type of question... but it's more that (and this is similar in respect to some of the architecture-related questions that you have had in the past) I would recommend staying with an “OO-way” of architecture.
So the answer is -- it depends. Where does this kind of CURL call lie within the functionality of the overall architecture of your application? Is it a service that you intend on running application-wide? If so, then you might want this kind of functionality in QApplication.
Or alternatively, is there something specifically that you are doing with the XML? e.g. if you are parsing out the values and updating a data class object, then the code would be much better in that particular data class within a method like RefreshFromCloudSponge() or something like that.
Hope that helps.