Socket.IO interface and search


for a diy project to run on a party I was looking for a way to generate a small user interface which allows searching for titles and adding them to a playlist without exposing much other fuctionality to the user (as in a kiosk mode).
My idea was to use the interface from a python client which again will spawn a small webserver that can be accessed by a tablet in a local wifi.
After reading the documentation here I was able to connect to volumio running on a RPi and I got answers to simple commands (play, pause, getState, etc.). But I didn’t have any success when trying to use the search functionality.
I tried the following calls

sio.emit('search', 'query')
sio.emit('search' {'value':'query'})

When watching with wireshark it seems I don’t get any replies. Can somebody help?