On Fri, Oct 19, 2007 at 09:53:27AM +0100, Richard W.M. Jones wrote: > Daniel P. Berrange wrote: > >Using structures in the public API is not in keeping with the rest of > >the libvirt APIs. We should be using XML for the main metadata description > >of volumes & pools. > > No, that doesn't make sense. XML for an API is a hack. It's hard to I disagree with you. XML is perfectly suitable for descriptions, especially when you need extendability and you can't control the future range of extensions. It's not proper for 'runtime' operations, but as a way to describe complex structures I find it fills its role perfectly. > use it without requiring an additional external library to parse the > XML. not an argument, "Security is a hack it requires external libraries to implement right" , doesn't work :-) > It's slow. For description, one time operation is absolutely not a problem. Plus libxml2 parses a 20+MBytes/s with current processors. > It has the facade of maintaining ABI compatibility > (because it's "just strings"), but in fact has no guaranteed ABI at all. You can't guarantee proper processing of something you can't describe in any case. Hard versionning with id in your stuctures can't guarantee anymore, if the code doesn't handle that version you're out. Actually with XML you can still extract the part of the structure you understand. And you can similary put ids labels in the structure allowing to introduce a radical change like the difference between a Xen or KVM definition. I still maintain that using XML for description (domains and network) was the best approach which allowed to go forward 2 years ago even if most of what we use now is very different from what was available at the time. And in front of the wide variety of storage options, I guess it's still the best choise to describe how to reach the data you want to access. Once the attach has been done, sure XML would be a bad format for operations in most case. But for description, which is what Dan suggested I totally agree with him. Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@xxxxxxxxxx | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/ -- Libvir-list mailing list Libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list