[libvirt] [PATCH 0/8] Normalization API

[Daniel P. Berrange]

On Wed, Sep 18, 2013 at 09:38:23AM -0600, Eric Blake wrote:
> On 09/18/2013 09:32 AM, Cole Robinson wrote:
> > 
> > Seems overkill IMO. Do we really need to add an API to facilitate the crappy
> > interface that is virsh detach-device? Will any other application ever want to
> > use this API?
> 
> Yes, I can envision other use cases.  In fact, virt-manager is one of them:
> 
> Oftentimes, we add features to XML, but you don't have an easy way to
> probe if the feature is supported.  Rather than complicate the (already
> large) capabilities xml to call out yet more features, it is rather
> simple to write up XML that tries to use the feature, then run it
> through the normalizing API, then look at the result.  If the feature is
> still present in the output, then libvirt understands the feature (and
> you can safely use it); if the feature got stripped as unrecognized,
> then you can issue a much nicer error message to the user stating that
> the libvirtd on the other end of the connection can't honor the user's
> request.

IMHO a better way to deal with that usage scenario is to add ability
to validate XML via the RNG schema to the API.

eg we should add a "validate" flag that can be passed to virDomainDefineXML
/ virDomainCreateXML that would enable RNG validation during parsing of
those APis. And possibly even have a dedicated API to request validation
of an XML doc in general (virt-xml-validate, but part of the API instead
of local CLI tool)

Daniel
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