Plan 9 from Bell Labs in Cyberspace!

Everyone who is anyone in tech is familiar with UNIX, the Bell Labs operating system that revolutionized computing systems by becoming the dominant OS on mainframes, workstations and web servers, and, as the progenitor of Linux, formed the foundation for the internet and cloud infrastructure we know today.

But what many don’t know is the team that created UNIX also developed another operating system in the 1980s. This OS may not be as famous as UNIX, but it has been highly influential in its own ways, spearheading several concepts that are cornerstones of distributed computing systems today. The system in question is the Plan 9 OS from Bell Labs, which, starting this week, will have a new home. More on that later, but first a bit more on the history and defining principles of Plan 9.

Starting in the late 1980s, a group led by Rob Pike and UNIX co-creators Ken Thompson and Dennis Ritchie developed Plan 9. Their motivation was two-fold: to build an operating system that would fit an increasingly distributed world, and to do so in a clean and elegant manner. The plan was not to build directly on the Unix foundation but to implement a new design from scratch. The result was named Plan 9 from Bell Labs – the name an inside joke inspired by the cult B-movie "Plan 9 from Outer Space."

Plan 9 is built around a radically different model from that of conventional operating systems. The OS is structured as a collection of loosely coupled services, which may be hosted on different machines. Another key concept in its design is that of a per-process name space: services can be mapped on to local names fixed by convention, so that programs using those services need not change if the current services are replaced by others providing the same functionality.

Despite the groundbreaking innovations in Plan 9, the operating system did not take off – at least not enough to justify Bell Labs continued investment in Plan 9 development. But Plan 9's innovations found their way into many commercial OSes: the concept of making OS services available via the file system is now pervasive in Linux; Plan 9's minimalist windowing system design has been replicated many times; the UTF-8 character encoding used universally today in browsers was invented for, and first implemented in, Plan 9; and the design of Plan 9 anticipated today’s microservice architectures by more than a decade!

Plan 9’s distributed design also lives on in current Nokia Bell Labs projects such as World Wide Streams where stream processing programs are seamlessly deployed across a network of compute nodes that are geographically spread across 5G edge and core clouds. But starting this week, Plan 9 will have a new home in the space it helped define: cyberspace. We are transferring the copyright in Plan 9 software to the Plan 9 Foundation for all future development, allowing them to carry on the good work that Bell Labs and many other Plan 9 enthusiasts have undertaken over the past couple of decades.

Indeed, there is an active community of people who have been working on Plan 9 and who are interested in the future evolution of this groundbreaking operating system. That community is organizing itself bottom-up into the new Plan 9 Foundation, which is making the OS code publicly available under a suitable open-source software license. We at Nokia and Bell Labs are huge advocates for the power of open-source communities for such pioneering systems that have the potential to benefit the global software development community. Who knows, perhaps Plan 9 will become a part of the emerging distributed cloud infrastructure that will underpin the coming industrial revolution?

And now it is simply left for me to smash the metaphorical magnum of champagne as Plan 9 sets sail on the next leg of her journey, to parts unknown.

The featured image shows members of the Bell Labs Computing Techniques Research Department, which developed Plan 9: (foreground, from left) Dennis Ritchie, Dave Presotto, Rob Pike, (background, from left) Tom Killian, Allen Eisdorfer, Tom Duff, Phil Winterbottom, Jim McKie, Howard Trickey and Sean Dorward.

Glenda, the Plan 9 Bunny, illustration by Renée French