Re: [libvirt] [RFC] Unify KVM kernel-space and user-space code into a single project

Daniel P. Berrange wrote: > On Fri, Apr 09, 2010 at 03:31:37PM +0100, Antoine Martin wrote: >> [snip] >>>> * not everything is exposed via libvirt: >>>> virsh can retrieve vncdisplay >>>> but libvirt (or at least the python bindings) does not. How come? >>>> This happens to be one thing I need for writing a libvirt backend for my >>>> virtual desktop software. >>> The 'virsh vncdisplay' command is simply fetching the XML doc for the >>> guest and then extracting the VNC port using a xpath expression >>> >>> /domain/devices/graphics[@type='vnc']/@port >>> >>> So for python you'd want to just get an XML handling module and do similar. >> Yes, I saw that in the virsh code. >> Shouldn't this be part of the libvirt api proper?? >> Isn't it supposed to shield us from dealing with files and XML? > > It isn't scalable to add APIs for extracting each possible piece of info > from the XML. All languages have APIs for extracting data from XML using > XPath (or DOM). Thus it is better to leave that flexibility to the apps > rather than hardcoding APIs for it in libvirt. The XML schemas/docs are > a formal part of the libvit API, so we're not trying to sheild that from > apps. > I was thinking of something like: domain.get_attribute("vncdisplay") Because it's a shame to have to use virsh as a wrapper (or XML file parsing) and re-do all the work that was done to get to the domain object when all your really want is just an attribute..