On Sun, Apr 26, 2009 at 8:15 AM, Tim Bray <Tim.Bray@sun.com> wrote:
On Apr 25, 2009, at 10:42 AM, Edmonds, AndrewX wrote:
I think one of the big things within presentation is the usage of OVF and
its status as a “1st class citizen” in their API
I've been looking at OVF. There's a lot to like there, but the thought of using it for *interop* is awfully scary. The notion of exposing various aspects of machine state or maybe even machine-group state in OVF seems plausible, but in the general case, importing OVF that someone else has produced and attempting to reproduce what it's describing, in an automated way, seems beyond the current state of the art.
I'd be unsurprised and pleased to be told "Everybody knows that, silly". I'd be surprised and delighted if someone put up their hand and said "Oh yes, we can do that for arbitrary OVF". Or possibly I'm just missing something obvious.
My original designs (I've been working on this problem since well before OCCI was conceived) had OVF embedded in Atom's content element. The intention was that it (and its eventual equivalents for storage and networking resources) be opaque except perhaps for a small but hopefully growing number of directives. Of course flat legacy formats (VMware's VMX for example) could be carried as CDATA as well and the number of Internet media (MIME) types the implementation supported would be a key differentiator/area of innovation. I've developed XSLT stylesheets to downconvert to ElasticHosts/GoGrid style flat text format, Q-Layer/Sun style JSON as well as upconverting to [X]HTML complete with microformats et al - the Atom base is borrowed from Google's GData. There's not actually much to the core protocol (except things like ETags for proxying/caching and conditional retrieval) and everything from state control to search is handled by extensions. All "resources" (having dropped the concept of "workloads" and "containers", so compute, storage and networking objects), are identified by a UUID which you can GET from <entrypoint>/<uuid> (e.g. http://example.com/5c60a787-c523-4859-831f-de5356eb3975). They can link to each other using standard Atom "link" relations and these have attributes for information like interface/device, IP number, etc. That is, key information that would normally hide inside OVF (including information about collections of systems) is specified in OCCI - if the level of interoperatility gets to a sufficiently high level then we can migrate over time but we may be pleasantly surprised as we get into the format discussion and start pulling it all apart. Sam