HELLO

Protocols: Redis RESP2 / RESP3

Negotiates protocol version. fastcached accepts version 2 and version 3. A connection starts in RESP2; HELLO 3 upgrades it, and every later reply on that connection uses RESP3 types.

Synopsis

HELLO [protocol-version]

Responses

• For HELLO or HELLO 2: a flat array describing the server (server name, version, proto = 2, id, mode, role)
• For HELLO 3: the same fields as a RESP3 map (%6), with proto = 3, and the connection is upgraded
• For any other version: -NOPROTO unsupported protocol version

Notes

• The upgrade is per connection and survives until it closes or RESET.
• RESET returns the connection to RESP2 along with clearing any transaction, watch set and subscription.
• What RESP3 changes on the wire — maps, sets, doubles, booleans, push and attribute frames — is in Redis RESP.