3.2. Network Protocol

checkpoint, size, version, and session_id are sent as 64-bit little-endian numbers.

3.2.1. Client to Server

Prefix	Data	Description
joedb	client_version	first message, sent at connection time
P	checkpoint	pull
L	checkpoint	lock-pull
p	checkpoint size data	locked-push
U	checkpoint size data	push-unlock
u		unlock
H	checkpoint hash (32 bytes)	check SHA-256 hash code
i		ping (used to keep the connection alive)
Q		quit

3.2.2. Server to Client

Prefix	Data	Description
joedb	server_version session_id checkpoint ‘R’ or ‘W’	reply to joedb. server_version = 0 means client_version is rejected. ‘R’ is pull-only
P	checkpoint size data	reply to P
L	checkpoint size data	reply to L
U		reply to U or p when the push succeeded
C		reply to U or p when the push failed (conflict)
R		reply to L, p, U or u when the server is read-only
u		reply to u (no timeout)
t		reply to u, U, or p in case of timeout
H		reply to H, hash is matching
h		reply to H, hash mismatch
i		reply to i