Darwin

1. operating system An operating system based on the

FreeBSD version of Unix, running on top of a microkernel

(Mach 3.0 with darwin 1.02) that offers advanced networking,

services such as the Apache web server, and support for

both Macintosh and Unix file systems. Darwin was

originally released in March 1999. It currently runs on

PowerPC based Macintosh computers, and, in October 2000, was

being ported to Intel processor-based computers and

compatible systems by the Darwin community.

2. programming, tool A general purpose structuring tool of

use in building complex distributed systems from diverse

components and diverse component interaction mechanisms.

Darwin is being developed by the Distributed Software

Engineering Section of the Department of Computing at

Imperial College. It is in essence a declarative binding

language which can be used to define hierarchic compositions

of interconnected components. Distribution is dealt with

orthogonally to system structuring. The language allows the

specification of both static structures and dynamic structures

which evolve during execution. The central abstractions

managed by Darwin are components and services. Bindings are

formed by manipulating references to services.

The operational semantics of Darwin is described in terms of

the Pi-calculus, Milner's calculus of mobile processes.

The correspondence between the treatment of names in the

Pi-calculus and the management of service references in Darwin

leads to an elegant and concise Pi-calculus model of Darwin's

operational semantics. The model has proved useful in

arguing the correctness of Darwin implementations and in

designing extensions to Darwin and reasoning about their

behaviour.

Distributed Software Engineering Section. Darwin publications.

E-mail: Jeff Magee [email protected], Naranker Dulay

[email protected].

3. Core War.

(2003-08-08)