EUMEL
Extendable multiUser Microprocessor ELan system, was an OS by Jochen Liedtke, with persistent processes and data spaces, built to offer a standalone environment for the educational programming language ELAN. In the words of Roland McGrath:"...EUMEL, was based on two simple principles: persistent processes and data spaces. All data of the entire system including process control blocks and data space descriptors were contained in these data spaces. They could be copied efficiently and atomically using copy on write and garbage collection techniques. By copying the "data space of data spaces" every few minutes, a complete copy of the entire system state was taken and lazily written out to disk. Thus, process persistence came for free (at least conceptually). Sending around data spaces in synchronous messages was the only means of process interaction which made it easy to build a simple distributed EUMEL system. The paging device was a floppy disk (what else on a cheap computer at that time)."
Later evolutions of EUMEL comprise the L3 and L4 OSes.
The following paper is also relevant: it shows this interesting system, which was in use in the so called "real-world", completely forgotten in favor of the C/Unix (presumed) portability or C/Microsoft Windows (presumed) easy of use (they are both crap, if you ask me). This tells all about the power of corporations (in this case: AT&T/Bell Labs, Microsoft, IBM, ...). -- MaD70
- A Persistent System in Real Use - Experiences of the First 13 Years (.ps 184 KB).
Abstract
Eumel and its advanced successor L3 are operating systems built by GMD which have been used, for 13 years and 4 years respectively, as production systems in business and education. More than 2000 Eumel systems and 500 L3 systems have been shipped since 1979 and 1988. Both systems rely heavily on the paradigm of persistent (including fault-surviving persistence). Both data and processes, in principle all objects are persistent, files are implemented by means of persistent objects (not vice versa) etc. In addition to the principles and mechanisms of Eumel/L3, general and specific experiences are described: these relate to the design, implementation and maintenance of the systems over the last 13 years. For general purpose timesharing systems the idea is powerful and elegant, it can be efficiently implemented, but making a system really usable is hard work. - Jochen Liedtke, its original developer.
This page is linked from: Orthogonal Persistence