The memo text:
> All teams will henceforth expose their data and functionality through service interfaces.
> Teams must communicate with each other through these interfaces.
> There will be no other form of interprocess communication allowed: no direct linking, no direct reads of another team’s data store, no shared-memory model, no back-doors whatsoever. The only communication allowed is via service interface calls over the network.
> It doesn’t matter what technology they use. HTTP, Corba, Pubsub, custom protocols — doesn’t matter.
> All service interfaces, without exception, must be designed from the ground up to be externalizable. That is to say, the team must plan and design to be able to expose the interface to developers in the outside world. No exceptions.
> Anyone who doesn’t do this will be fired.
> Thank you; have a nice day!
It wasn't one specific memo, but rather a series of guidances from leadership down and through the Principal Engineering community to both incentivize and require this kind of interop.
Also, a lot of folks (not you, but inb4) focus on the last 2 lines because it fits with their narrative of an idea of what Amazon is like. For the record, nobody sent out (or sends out) a memo with a "do this, or you will be fired" conditionals. (I'm sure there are extreme cases where HR is already involved and people are on their final notice. I'm also sure there might have been some anti-union-busting b.s. or how the climate change activists got fired in a way that i personally don't agree with. But it's not a standard practice)