Roles of princess seems to be very vague...
Princess Diana mentioned she had to find out what she needs to do herself.
I guess every individual princess will have to portray a certain (good) image thus their roles will not differ too much.
But generally, Princess has to balance her public and private life.
(Do they really have a private life? Is their life all about maintain the 'perfect' image of the royal princess and produce a heir for the family?)
They'll have to face alot of pressure from the royal family as well as the media and public.

The feminine form of prince (from Latin princeps, meaning principal citizen). Most often, the term has been used for the consort of a prince, or her daughters.

source: http://en.wikipedia.org/wiki/Princess

Early in the 17th century, archive is in the sense of a place where records are kept:
from French archives, from Latin archiva, archia, from Greek arkheia 'public records', from arkhe 'government'. The verbs dates from the late 19th century.

In today's term, it is a collection of historical documents or records providing information. Also can be a place or store in such a collection or place.