[Libvirt-cim] [RFC] override CreateSnapshot extrinsic

Since the CreateSnapshot() extrinsic has 2 vendor defined values added for SnapshotType parameter, I think the method should be overridden to define these new values. The attached patch does so by creating a new class Virt_VirtualSystemSnapshotService where CreateSnapshot is overridden. The various virtualizer flavors then inherit from Virt_VirtualSystemSnapshotService instead of CIM_VirtualSystemSnapshotService directly. Some tools will parse the class info and format gui based on qualifiers it finds. In the case of CreateSnapshot, such tools will not display the vendor additions unless we override the method and describe the additions. While on the subject, I would like to understand the usefulness of SnapshotType 32768. This type will save the vm's memory state and subsequently restore the vm. IMO applying this memory snapshot later would be quite dangerous. The vm has since been running and the disk state will be quite different from when the memory snapshot was taken. Does this make sense or am I not thinking clearly :-)? Finally, invoking CreateSnapshot with SnapshotType 32769 will save the vm and leave it powered off. Querying EnabledState shows the vm 'Enabled but Offline' (suspended). According to System Virtualization Profile, one should be able to move a vm in this state to Enabled by invoking RSC(Enabled) but doing so results in "snapshot exists, apply snapshot" error. So the behavior diverges from the spec IMO. It seems the current behavior of SnapshotService should just be implemented via RSC. CreateSnapshot -> RSC(Enabled but Offline), ApplySnapshot -> RSC(Enabled) Regards, Jim