Re: [libvirt] [PATCH 0/8] Normalization API

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)