tr2011004_steps11

“NoOS = No Operating System”
In the conventional sense, STEPS does not really have an “operating system”, nor does it use one. Instead
the STEPS system is thought of as existing on an Internet of linked physical computers as a virtual
network of communicating virtual machines (“real objects”).
Today’s physical computers themselves have virtualized versions of themselves manifested as
“processes” which have their own confined address spaces. The STEPS strategy is to map its networks of
communicating real objects over the physical‑and‑virtual mechanisms provided by the physical
hardware. In short, to STEPS, the world of physical computing resources is viewed as caches for its
mobile computations.
The “NoOS” model for STEPS. The circles are physical computers, the light blue thick arrows are physical network connections. The
red hexagons are “object/processes”; the dark blue arrows are messages. The user of a distributed mobile computation will have
objects close by to create a UI, views, and controls. The code needed on each physical computer for resource allocation is tiny.
Much of this is future work for the STEPS project. One of our influences has been David Reed’s 1978 PhD
thesis [NETOS], and we have previously implemented several versions of this [Croquet]. Another
influence was the [Locus] migrating process operating system of heterogeneous hardware done by Gerry
Popek and colleagues in the 80s.
In order for a computer to act as a cache for STEPS, something does have to be written, and one could call
it an “operating system”. In fact, it would be very much like the parsimonious kernels for OSs that have
been done neatly and nicely over the years by individuals (for example the Linux kernel in about 1000
lines of code by Linus Torvalds—and this followed the original notion of Unix that almost all of it be
vanilla code; only the bare essentials should be special). The bloat that followed (Linux is really large
these days!) is mostly a result of various kinds of dependencies, poor design, and perhaps even the weak
paradigms of “economies of scale” and “central shared facilities”.
By restricting the local code on a physical computer to simple caching and safe access to resources, we
think that STEPS can emulate the inspiring small TCP/IP kernels which have allowed the Internet to scale
by many orders of magnitude without themselves getting polluted by dependencies.
VPRI Technical Report TR-2011-004
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