Server to Client Query

[John Leiseboer <JL@quintessencelabs.com>]

As requested on the call today, I am sending a description of the server to client query issue that was discussed in the TC call on June 19.

There is an asymmetry in KMIP, such that KMIP clients may use a proxy to connect to a KMIP server, where the proxy terminates the TLS connection with the server. This asymmetry does not permit a server to directly address a client sitting behind the proxy for server to client messages. Incidentally, this is also an issue for the Notify and Put operations, and could perhaps be resolved in a similar manner.

This is not an issue in the client to server direction because:
a. The server is the end point (as far as KMIP request messages are concerned) and we do not (yet) have the concept of a server proxy in KMIP;
b. As the proxy is acting on behalf of clients, it can manage the pairing of requests and their responses, and map these to its end-point clients.

There are many practical examples of this type of configuration: tape library as proxy to tape drives; disk array controller as proxy to disk drives; VM manager as proxy to VM instances; communications controller as proxy to radio receivers and transmitters; key loader as proxy to end-point encryption devices; etc.

As expressed on the call, some TC members' products, and customers, support configurations where clients with DIFFERENT capabilities connect through a proxy. The current proposal for server to client queries assumes a one-to-one direct relationship between the server and the client. The proposal does not specify how a server can direct a query to a specific end-point client behind the proxy, or how a proxy can indicate which end-point client a query response applies to.

I will try to describe some of the possible solutions to this in a later email. Right now, I have other work to do.

John

John Leiseboer | Chief Technology Officer | QuintessenceLabs | W: quintessencelabs.com
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