Informations about items in GTFS protobuf file

[kalon33]

Dear @clinct , would it be possible to give a list of possible ent.alert, ent.trip_update and ent.vehicle_positions elements?

I'm struggling creating a GTFS-RT feed setting these elements in Python, in particular ent.alert ones (cause, timerange, description_text, header_text, route_id...) and trip schedule_relationship. I've all data in variables but don't know how to set them in my Python script to make a feed after some weekends of work...

Thanks for your help.