Open standardized protocols are what made the Web possible. We have standards all the way up the computational stack, from agreeing on which pins mean what in a wire, to what an X button means in a user-interface. Companies who don’t embrace them are destined to isolate themselves on tiny technological islands. Specific implementations, however, don’t have to be shared and open. Huge markets with tiny verticals of implementation lock out competition, but they also prevent innovation. But sometimes something beautiful happens, and people get together to support a new kind of standard. An open, extensible standard that can be written and read by anyone. One place where this is just starting to happen is with computer virtualization.
The Open Virtual Machine Format, or OVF is a proposed universal format that aims to create a secure, extensible method of describing and packaging virtual containers. Because the standard is open, it means any environment supporting the standard can import and export those virtual machines between different hypervisor platforms. The current OVF specification includes definitions ranging from virtual machine metadata and disk format, all the way to detailed hardware specifications and logical network information. It also provides an ability for the virtual machine itself to get information from the hypervisor host, meaning that if you’re creative you could create some really nifty automated integration and deployment tools.
If that doesn’t mean much to you, then consider this: Industry heavy-weights like Dell, HP, IBM, Microsoft, VMware, and XenSource all took part in drafting the specification. As far support tools go, VMware has published what appears to be the first OVF container creation tool, available here.
There IS a big problem with OVF right now, and a lot of bloggers and analysts out there are getting it wrong. OVF is not and does not define a new virtual disk format, simply a wrapper around them. This means that OVF support doesn’t enable you to drag and drop virtual machines between Xen and VMware. Some formats can be converted externally using tools, however most of the current techniques involve booting up a system, and running a migration tool to be able to convert the image - not exactly ideal. OVF does include the ability to describe your specification in an HREF, which means that you could publish your spec, and create a system that could modify containers on the fly.
If Vmware, Xen, and Parallels are technolgical islands, then OVF may one day be the bridge that will allow you to travel between them.