Redis serialization protocol RESP written in Go Programming language
Redis serialization protocol (RESP) is the wire protocol that clients implement To communicate with the Redis server, Redis clients use a protocol called Redis Serialization Protocol (RESP). While the protocol was designed specifically for Redis, can be used for other client-server software projects.
RESP is a compromise among the following considerations:
Simple to implement. Fast to parse. Human readable. RESP can serialize different data types including integers, strings, and arrays. It also features an error-specific type.
RESP is binary-safe and uses prefixed length to transfer bulk data so it does not require processing bulk data transferred from one process to another.
RESP is essentially a serialization protocol that supports several data types. In RESP, the first byte of data determines its type.
RESP is a binary protocol that uses control sequences encoded in standard ASCII. The A character, for example, is encoded with the binary byte of value 65. Similarly, the characters CR (\r), LF (\n) and SP ( ) have binary byte values of 13, 10 and 32, respectively.
The \r\n (CRLF) is the protocol's terminator, which always separates its parts.
The first byte in an RESP-serialized payload always identifies its type. Subsequent bytes constitute the type's contents.
We categorize every RESP data type as either simple, bulk or aggregate.
Simple types are similar to scalars in programming languages that represent plain literal values. Booleans and Integers are such examples.
RESP strings are either simple or bulk. Simple strings never contain carriage return (\r) or line feed (\n) characters. Bulk strings can contain any binary data and may also be referred to as binary or blob. Note that bulk strings may be further encoded and decoded, e.g. with a wide multi-byte encoding, by the client.
Aggregates, such as Arrays and Maps, can have varying numbers of sub-elements and nesting levels.
The following table summarizes the RESP data types that Redis supports:
| RESP data type | Minimal protocol version | Category | First byte |
|---|---|---|---|
| Simple strings | RESP2 | Simple | + |
| Simple Errors | RESP2 | Simple | - |
| Integers | RESP2 | Simple | : |
| Bulk strings | RESP2 | Aggregate | $ |
| Arrays | RESP2 | Aggregate | * |
| Nulls | RESP3 | Simple | _ |
| Booleans | RESP3 | Simple | # |
| Doubles | RESP3 | Simple | , |
| Big numbers | RESP3 | Simple | ( |
| Bulk errors | RESP3 | Aggregate | ! |
| Verbatim strings | RESP3 | Aggregate | = |
| Maps | RESP3 | Aggregate | % |
| Sets | RESP3 | Aggregate | ~ |
| Pushes | RESP3 | Aggregate | > |