VersionHandshake
The version handshake between two members of a consensus group.
This file is frozen for the life of the product: its package, service, method and messages never change, so that members of any two releases can tell each other which version they run. Members whose versions differ exchange nothing but this.
The same record also travels in the cn-version-handshake-bin request and response metadata of every other inter-node call; a call whose record does not match the receiver's version is refused before its payload is read.
Proto source
Methods
Exchange
Exchange version records. Answered whether or not the two members match; the caller compares the records itself.
Request: HandshakeRecord
| Field | Type | Description |
|---|---|---|
record | bytes | The record in its frozen binary encoding: magic "CNVH", then little-endian node id (u64), group id (u64), the sender's engine format version (u32) and host format epoch (u64); a presence byte and, when 1, the pair its group runs as far as the sender knows (engine u32, host epoch u64) with the number of the record that set it (u64, numbered in log order from 1); a presence byte and, when 1, the group's leader as far as the sender knows: node id (u64), address length (u16) and UTF-8 address. Produced and checked by the engine, never by a client. |
Response: HandshakeRecord
| Field | Type | Description |
|---|---|---|
record | bytes | The record in its frozen binary encoding: magic "CNVH", then little-endian node id (u64), group id (u64), the sender's engine format version (u32) and host format epoch (u64); a presence byte and, when 1, the pair its group runs as far as the sender knows (engine u32, host epoch u64) with the number of the record that set it (u64, numbered in log order from 1); a presence byte and, when 1, the group's leader as far as the sender knows: node id (u64), address length (u16) and UTF-8 address. Produced and checked by the engine, never by a client. |
Types
HandshakeRecord
One member's version record.
| Field | Type | Description |
|---|---|---|
record | bytes | The record in its frozen binary encoding: magic "CNVH", then little-endian node id (u64), group id (u64), the sender's engine format version (u32) and host format epoch (u64); a presence byte and, when 1, the pair its group runs as far as the sender knows (engine u32, host epoch u64) with the number of the record that set it (u64, numbered in log order from 1); a presence byte and, when 1, the group's leader as far as the sender knows: node id (u64), address length (u16) and UTF-8 address. Produced and checked by the engine, never by a client. |