How to "listen" for 15 minute bar updates?

Alpaca Market Data
2

Hi,
you could use the websocket subscription with AM (aggregated minutes), and then test if 15 minutes past since your last operation.
then you could take the 15 1 minute bars and resample them to 1, 15 minute bar.
if you save them in a dataframe you could do it like this:

df.resample('15T').agg(dict(
                    open='first',
                    high='max',
                    low='min',
                    close='last',
                    volume='sum',
                ))

if you save them as bars, just do the operations described manually