@r2evans approach 3 with the wrapper function looks very promising. For shiny I used approach 1 (more or less) but that doesn't work if the connection breaks while the query is executed. Thank you for your input,very much appreciated.

I was just wondering because an instable connection should be a "standard problem" - whenever i work remote with portable WiFi hotpost it happens quite frequently that connection says 'good bye' - didn't expect that it's neccessary to implement something by myself