Key points are not available for this paper at this time.
The x-kernel is a configurable operating system kernel designed to support experimentation in interprocess communication and distributed programming. The x-kernel's underlying architecture provides a rich set of abstractions that are used to construct and compose communication protocols. The architecture is interesting because the abstractions are both general enough to accommodate a wide range of protocols and efficient enough to provide a useful testbed in which protocol performance can be accurately measured.
Hutchinson et al. (Mon,) studied this question.