MessagePack (serde/msgpack)

MessagePack is a compact binary serialization format. It's significantly smaller than JSON in wire size and faster to parse since there's no text tokenization involved—just direct byte reading.

Modules

File	Purpose
encoder.vx	Struct → binary MsgPack bytes
decoder.vx	Binary MsgPack → Struct
value.vx	MsgPackValue dynamic type tree
serde.vx	Contract-based Serializer/Deserializer implementations

When to Use

• RPC and IPC: Inter-process communication where bandwidth matters.
• Network Protocols: Custom binary protocols between Vex services.
• Storage: Compact struct serialization for caching or databases.
• High Throughput: When JSON text parsing overhead is unacceptable.

Encoding

import { encode } from "serde/msgpack";

struct Sensor {
    id: i64
    temperature: f64
    active: bool
}

let data = Sensor { id: 42, temperature: 23.5, active: true };
let bytes = encode<Sensor>(&data);
// Compact binary: ~15 bytes vs ~50+ bytes in JSON

Decoding

import { decode } from "serde/msgpack";

let! sensor = Sensor { };
decode<Sensor>(bytes, &sensor);
println("Sensor {sensor.id}: {sensor.temperature}°C");

Wire Format

MessagePack uses type-prefix bytes to encode values efficiently:

Type	Prefix	Size
Positive fixint	0x00–0x7f	1 byte
Negative fixint	0xe0–0xff	1 byte
fixstr	0xa0–0xbf	1 + N bytes
fixarray	0x90–0x9f	1 + elements
fixmap	0x80–0x8f	1 + entries
float64	0xcb	9 bytes
int64	0xd3	9 bytes
true/false	0xc3/0xc2	1 byte
nil	0xc0	1 byte