ICalendar and Outlook subscription

[Robert Isidorsson]

I would like to publish a calendar to be subscribed from a Outlook calendar, im using ical4j to create a ICalendar format with data from a sql database.
What are the requirements to publish such a service? Can i just produce the icalender on the fly and set the mime type to text/ics or any appropriate? Or do i have to support the webcal protocol or such?
In outlook the url for subscription have to be webcal:// or can i use http as well?