Pubsubd was the second iteration of the pubsub system that we used, mostly, for cache invalidation in Combosaurus across the lot of services we had.
The [original design](ORIGINAL.DESIGN.org), was considered to be ideal, but not practical, and I implemented a different strategy.
Rather than the client exposing a server, the client essentially opened up a long lived TCP connection to pubsubd, gave it’s subscription id, and recieved MsgPack data representing published messages, or Pings.
This was written in 2012.
This code will not compile, as it is missing some important parts that are not open. However, it’s the 2nd Go program I ever wrote, and I was quite happy with it. No idea how I’d rate it today. :)