B0.1 · dive 1 of 3
The one relocation.
The single move the whole system is built on: take the boundary object orientation draws around the object, and draw it around the system instead.
The idea
the law · the one moveObject orientation drew the encapsulation boundary around the object: its data and the methods over that data lived together, and the boundary was the object’s own surface. The Branded Component System keeps encapsulation and moves the boundary outward, around the system. The state an object used to hold privately now lives inside the system that owns it, and what leaves the object is the one thing a distributed program can carry between machines — its name.
The relocation promotes the name from a detail to the interface. A system no longer hands another system a reference to an object; it hands a branded identity and a message about it, and everything the receiver can do, it does by asking the owner. The coupling that once travelled as a shared object now travels as a question about a name.
The move looks like a loss — you give up the convenience of reaching into an object — and it buys three things the object model could not keep across a boundary: a value that survives the process, a value that means the same thing on another machine, and a value a database can hold and order. The rest of the course is the consequence of this one line, drawn around the system instead of the object.
The doors
the sibling coursesEchoMQ — the protocol, in depth
The bus B3 narrates, taught rung by rung: the keyspace, the Lua inventory, and the 3.0 Stream Tier — XADD, XREADGROUP, XACK — with conformance on Valkey.
Redis Patterns Applied
The substrate patterns under the bus: sorted sets, atomic Lua moves, locks, and streams — the judgement layer.
/echo-persistenceEcho Persistence — the durable floor
Beneath the volatile tiers: the Graft page engine built twice, the commit-LSN loop, and the stream archive on Tigris. Where Part I says state lives somewhere, this says where it lives durably.
References
sources · relatedSources
- Leonard — Postmortem: Thief: The Dark Projectthe Dark Object System that relocated the boundary in shipping code
- The Go Project — Share Memory By Communicatingownership behind a boundary, identities across it
- Erlang/OTP — the ets modulethe per-system private table the relocation lands in
Related
- BCS — the course homethe law, the id anatomy, the chapter map
- Echo Persistencethe durable floor beneath the bus