[Libvir] A question about libvirt usage

Is there a notion of session in libvirt ? In other words, is it possible, between virConnectOpen() and virConnectClose(), that some Xen domains will be started, stopped, destroyed, etc.. by another operator using the xm command ou by another binary command based on libvirt. If the response is yes, is it possible to introduce a global lock in Xen (or in libvirt ?) to avoid conflict between libvirt and xm command or between several libvirt based commands. Thanks, Philippe Berthault.