Meta server: start on the delegation renew implementation where delegation renewal and cancellation can be performed by the authenticated users other than the delegation token owner. The list of users that are allowed to renew delegation tokens that belong to other users can be configured by specifying a list of user names or groups. In the case of groups all users that are member of such group will be granted permissions to renew or cancel delegation tokens that belong to other users.
Replace "type of" like rpc handling conditionals in the client state machine with more generic interface such that any derived meta request class can implement / override "dispatch" handler which is invoked from the client thread context.