§12. Cluster

In this chapter

12.1 Cluster declaration	A program has at most one cluster.
12.2 Membership and roles	A node finds seed nodes and joins the membership (SWIM protocol).
12.3 Routing and neighbour discovery	A call of service S
12.4 Shards	The built-in storage is divided into shards virtual shards (set once).
12.5 Sharded actors	The key is declared in the header (sharded by name
12.6 Distributed computation	cluster.shards(src) is for sharded tables and actors; map runs close to the data, the function MUST be transferable (§7.3).
12.7 Dependencies	provide Type = expression (for role r, …)?
12.8 Built-in storage and tables	The storage is on every node of the journal role, replication is Raft per shard.