[libvirt-users] The Format Of URI when Migrating

Hi, when I try to use such API: virDomainPtr <http://www.libvirt.org/html/libvirt-libvirt.html#virDomainPtr> virDomainMigrate (virDomainPtr <http://www.libvirt.org/html/libvirt-libvirt.html#virDomainPtr> domain, virConnectPtr <http://www.libvirt.org/html/libvirt-libvirt.html#virConnectPtr> dconn, unsigned long flags, const char * dname, const char * uri, unsigned long bandwidth) to achieve the domain to the remote host. I set the "const char * uri" as "qemu+ssh://root@116.56.142.199/system". But the Error "libvir: QEMU error : invalid argument in only tcp URIs are supported for KVM/QEMU migrations" happened. I want to know when i want the migrate ,how can i set the URI ? offer a example is better. :-)