[Libvir] [RFC] Host and guest capabilities

Richard W.M. Jones rjones at redhat.com
Wed Mar 7 14:56:47 UTC 2007

Daniel Veillard wrote:
>   This sounds too variable, adding an entry point per capability of
> some of the hypervisor available will lead to just too many entry points
> once the set of virtualization engines and associated benefits increase.
> That's one of the places where I feel wy more comfortable returning an
> XML description which can then be augmented as more features are added.

But this API is _precisely_ designed to be extensible.  The 
virCapabilities structure is not accessible to callers (unlike, say, 
virNodeInfo), except through accessor functions.  We can add accessor 
functions in future.

Returning XML just punts the problem elsewhere.  Now clients need to 
worry about parsing the XML, and there's no real guarantee that the XML 
won't change in a way which is incompatible with the clients.  Whereas 
by using ordinary functions we have that guarantee.


Emerging Technologies, Red Hat  http://et.redhat.com/~rjones/
64 Baker Street, London, W1U 7DF     Mobile: +44 7866 314 421
  "[Negative numbers] darken the very whole doctrines of the equations
  and make dark of the things which are in their nature excessively
  obvious and simple" (Francis Maseres FRS, mathematician, 1759)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 3237 bytes
Desc: S/MIME Cryptographic Signature
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20070307/5ad79df0/attachment-0001.bin>

More information about the libvir-list mailing list