[dhodell]

Ironically, several folks who worked on Plan 9 later worked (or continue to work) at Google, although none of them worked on Fuchsia.

<ramble> To me the major overlap between them is their designs are clearly informed by the contemporaneous shape of network architectures. Fuchsia is a take on what an OS design would be as a set of named microservices that can be routed. Plan 9 noticed network topologies of compute labs and clusters weren't too different, and both graphs could be represented in filesystems. The major visible difference to me is that the visibility of routing is much more apparent in Plan 9 than it is in Fuchsia. It's still a little difficult to understand how and where capabilities propagate through the system.

Implementation-wise, FIDL is a much different take than 9P2K. Though much simpler, 9P2K forces every API to exist via a filesystem interface (many of the higher level protocols also involve quite a lot of string passing) and struggles with throughput of streaming operations. Individual FIDL APIs might have similar problems, but the message encoding itself is relatively more efficient. </ramble>