SPACE: A New Approach to Operating System Abstraction

Object-oriented operating systems, as well as conventional O/S designs, present an overly restrictive level of abstraction to the programmer. Models of objects, processes, concurrency, etc., are embedded within the system in such a way that they are di cult to extend or replace. SPACE is an extensible operating system being developed for research into object-oriented and distributed systems design. SPACE uses capability mechanisms based on the manipulation of address spaces to provide low-level kernel primitives from which higherlevel abstractions can be constructed. Standard micro-kernel abstractions such as processes, virtual memory, interprocess communication, and object models are built outside the kernel in SPACE, using the SPACE-kernel primitives: spaces, domains, and portals. Multiple versions of the standard O/S abstractions can coexist and interact.