HELLO
Select the RESP protocol version for this connection and return server metadata.
HELLO [2|3 [AUTH username password] [SETNAME client-name]]Every socket and RESP-over-ring connection starts in RESP2. HELLO 3 switches that connection to RESP3; HELLO 2 switches it back. A bare HELLO reports metadata using the connection's current version without changing it.
When an auth file is configured, AUTH verifies the connection as part of the same exchange. SETNAME assigns the client name returned by CLIENT GETNAME. The options may appear in either order, but the protocol version is required when either option is present. Goblin validates the complete request before changing protocol, identity, or name.
HELLO may be sent after other commands. The HELLO reply itself uses the selected version, and the selection applies immediately to commands already queued behind it in the same pipeline. Other connections are unaffected.
An unsupported version returns:
-NOPROTO unsupported protocol versionand leaves the current version unchanged.
Reply
The reply contains server, version, proto, id, mode, role, and modules. RESP3 encodes these fields as a map; RESP2 encodes the same alternating key/value fields as an array.
Goblin emits native RESP3 shapes for replies whose RESP2 representation loses type information:
| Command or value | RESP2 | RESP3 |
|---|---|---|
| Missing value/member | null bulk string | null |
HGETALL |
alternating array | map |
GOBLIN.MEMORY |
alternating array | map |
ZSCORE, INCRBYFLOAT |
bulk string | double |
ZRANGE ... WITHSCORES |
flat member/score array | array of member/double pairs |
Simple strings, errors, integers, bulk strings, and ordinary arrays are valid in both versions and retain their existing wire forms.
SBE
RESP negotiation does not affect SBE. When the server is started with --enable-sbe, an endpoint whose initial bytes are GOBLINS! selects the SBE wire for that connection. SBE is a trusted-fabric protocol and does not use RESP authentication.