In Redis Pub/Sub, the messaging format is in RESP Array reply with three or four elements. The first element in the Pub/Sub messaging format determines the type of message and can be one of these four Redis commands,
Connecting to a Redis instance with two connections, the first with a standard Redis CLI client and the second with telnet, we will illustrate the RESP reply for three element commands
$ telnet localhost 6379 Trying ::1... Connected to localhost. Escape character is '^]'. SUBSCRIBE info *3 $9 subscribe $4 info :1
SUBSCRIBE command, the first element is
$9 followed by carriage-return line feed. ...