Redis communication protocol

Example command to understand the protocol

import redis
client = redis.Redis()
client.set('a', 'hello') # SET 'a' 'hello'

Conversion of the above command by redis client

*3\r\n
$3\r\n
SET\r\n
$1\r\n
A\r\n
$5\r\n
hello\r\n

Things to note here are:

• Every line ends with \r\n
• Explanation of the above command sequence line-by-line (not showing \r\n)
  • *3 - Indicates that there are three arguments in the command (SET 'a' 'hello'). Note that this line starts with *
  • $3 - Number of bytes in the upcoming argument (SET is 3 bytes long). Note that this line begins with $
  • SET - The argument itself
  • $1 - The next argument is 1 byte long
  • A - The argument
  • $5 - The next argument is 5 bytes long
  • hello - The argument

Response from server

+OK\r\n

The command was successful

Another example

client.get('a') # GET 'a'

The above python code gets converted to the following by the client:

*2\r\n
$3\r\n
GET\r\n
$1\r\n
a\r\n

The server responds with:

$5\r\n      -> The response is 5 bytes long
hello\r\n

Sources

• The Redis Protocol is pretty good