RE: Entity: thoughts

Mike,  Great summary and a cool story. Certainly helped my thought process.  I'd like to suggest a simpler use-case that we can also pick apart in our further discussions.  Here is how I understand the promise of interoperability, the big I in our favorite 4-letter acronym.
Using your Sienar Systems example, suppose Sienar uses a key management server from vendor X. If, for whatever reason, Sienar is forced to use a server, from vendor Y, they can do so without much effort, provided that servers from X and Y interoperate. In a perfect world, Sienar would seamlessly backup keys and configuration on server x from X, restore it on server y from Y and continue as if nothing happened. This is fairly far-fetched. At the other extreme, server y, a perfectly compliant KMIP server, may have no support whatsoever for any user list/directory, no concept of key access control by different clients. This, of course, is discovered only after a big contract with Y has been signed and now Sienar engineers are forced to re-design their entire system.  I am wondering if there is something fairly concrete between these two extreme scenarios? If there is, is it possible to define it using means at our disposal? And finally, is Entity proposal the right context for this?  Regards, Denis