A citizen/customer should be able to fill out forms without having to authenticate first

[bwrobert]

In order to submit the form authentication is required.

If a user presses the save button provided by Orbeon the form is saved along with the session id. As long as the user keeps the session the form data persists. When the session is closed the form is cleared. The session should only persist as long as the browser is open.

Saved but unsubmitted forms need to be purged at regular intervals, preferably whenever the session is closed.

[bwrobert]

SOLUTION

Use two different forms: one for non-authenticated users, another for authenticated users. Forms for non-authenticated users should not have a save button. Forms for authenticated users should have a save button.

The forms for non-authenticated users should be primary choice.