Yes, I believe I know what this is... the contents of xenstore for dom0 aren't
setup properly. I've got an experimental patch to fix this in progress.
In the meantime you can probably workaround the problem by running (hopefully I
remember the exact path!)
xenstore-write /vm//name "Domain-0"
xe
I'm not sure it's possible to do this - the XAPI web interface is very simple -
although I'll let someone else who knows for certain to comment too.
I just wanted to highlight that the example from the blog post was about
creating a XenAPI plugin that allows you to upload something already exist
