The docs [login required] state that your web application cd_ambient_conf.xml should contain the following cartridges when setting up Session Preview:
<Cartridge File="cd_webservice_preview_cartridge.xml"/>
<Cartridge File="footprint_cartridge_conf.xml"/>
Firstly, is that a typo with the first cartridge? We are using session_cartridge_conf.xml
and it works fine. UPDATE: I see that session_cartridge_conf.xml is for SmartTarget, so ignore this.
Secondly, what do these cartridges actually do? I can't find it described anywhere in the docs. I had assumed that the footprint cartridge overrides values in the ADF from Footprints sent by XPM, however we do not have this configured, yet Footprints seem to work just fine.