when a new appointment is created it is possible to check whether the user is free for this event?
Now i create ne events with a flexible number of responsible employeers (multiple checkboxes). When I create a new event, I would like to check whether I can assign the employee for that time period.
You can call scheduler.getEvents(start_date, end_date) which will return an array of events, which are occurs in the same time. Now you can iterate through them and check if any belongs to the user in question - if you fill find 2 or more such events - than you have a collision.
collision extension can do it automatically in unit|timeline view ( here it will block event creation if unit in question already has some event for that time )