CBOR (serde/cbor)

CBOR (Concise Binary Object Representation, RFC 8949) is an extremely compact binary format designed for constrained environments like IoT devices, embedded systems, and low-bandwidth networks.

Modules

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

When to Use

• IoT Telemetry: Sensors sending compact payloads over constrained networks.
• Embedded Systems: Minimal memory footprint for data exchange.
• WebAuthn/FIDO2: CBOR is the standard encoding for authenticator data.
• COSE (CBOR Object Signing): Signed and encrypted CBOR objects in security protocols.

Encoding

import { encode } from "serde/cbor";

struct SensorReading {
    device_id: i64
    temperature: f64
    humidity: f64
}

let reading = SensorReading { device_id: 1001, temperature: 22.5, humidity: 65.3 };
let bytes = encode<SensorReading>(&reading);
// Extremely compact binary output

Decoding

import { decode } from "serde/cbor";

let! reading = SensorReading { };
decode<SensorReading>(bytes, &reading);
println("Device {reading.device_id}: {reading.temperature}°C");

CBOR vs MessagePack

Feature	CBOR	MessagePack
Standard	IETF RFC 8949	Community spec
Tags	Yes (datetime, bignum, URI)	No
Indefinite-length	Yes	No
Web standards	WebAuthn, COSE	Redis, Fluentd
Size	Slightly larger (tags)	Slightly smaller