Process services are quite simple in Off. The only abstraction provided is the Shuttle. A shuttle is an extensible hardware context. Initially, it consist only of a program counter and a stack pointer, though they can be safely extended later on to include other pieces of context (such like general purpose registers, address spaces, privilege levels, etc.)
In other systems the process subsystem is fixed and must be re-implemented (at least in part) to modify the provided process abstraction [12]. In Off it suffices to extend the shuttle with a new piece of context (property). Properties must not be the same for every shuttle in the system, giving the possibility of using different process abstractions in the same system at the same time.
Shuttles, like other Off abstractions, are not attached to a particular processor. As our system considers the whole network, each available processor will be able to run a shuttle even if it was previously in a different node, so shuttles can migrate.