Implementing Self-Managing Protection Domains in Charm

We believe that the engineering of mobile or persistent processes is hindered in many systems by the amount of coupling between user-level and the kernel. This coupling usually takes the form of user level data structures containing opaque references to kernel data structures. In this paper we show how self-managing protection domains may be constructed that support a modern object-oriented application environment that is not closely coupled with the kernel. This is achieved through the introduction of a software artefact called the Umbrella that abstracts over the low-level aspects of self-management and present a clean object-oriented management interface to the upper layers of software. We show how the Umbrella is engineered and some of the problems that must be overcome in order to achieve isolation from the kernel. We conclude by showing how a thread system may be constructed above the Umbrella.