I can retrieve some very basic data with:
OW::getUser()->getUserObject()
But I have no idea how to retrieve roles an user belongs to. Any idea ?
Use the authorisation service class. See example below:
// list user roles of currently logged in user
$userId = OW::getUser()->getId(); // get current user Id
BOL_AuthorizationService::getInstance()->findUserRoleList($userId); // list user roles