musli-wire

Fully upgrade stable format for Müsli suitable for network communication.

Wire encoding is fully upgrade stable:

• ✔ Can tolerate missing fields if they are annotated with #[musli(default)].
• ✔ Can skip over unknown fields.

This means that it's suitable as a wire format, since the data model can evolve independently among clients. Once some clients are upgraded they will start sending unknown fields which non-upgraded clients will be forced to skip over for the duration of the upgrade.

use musli::{Encode, Decode};

#[derive(Debug, PartialEq, Encode, Decode)]
struct Version1 {
    name: String,
}

#[derive(Debug, PartialEq, Encode, Decode)]
struct Version2 {
    name: String,
    #[musli(default)]
    age: Option<u32>,
}

let version2 = musli_wire::to_vec(&Version2 {
    name: String::from("Aristotle"),
    age: Some(62),
})?;

let version1: Version1 = musli_wire::decode(version2.as_slice())?;

assert_eq!(version1, Version1 {
    name: String::from("Aristotle"),
});

Configuring

To configure the behavior of the wire format you can use the Encoding type:

use musli::{Encode, Decode};
use musli_utils::options::{self, Options, Integer};
use musli_wire::Encoding;

const OPTIONS: Options = options::new().with_integer(Integer::Fixed).build();
const CONFIG: Encoding<OPTIONS> = Encoding::new().with_options();

#[derive(Debug, PartialEq, Encode, Decode)]
struct Struct<'a> {
    name: &'a str,
    age: u32,
}

let mut out = Vec::new();

let expected = Struct {
    name: "Aristotle",
    age: 61,
};

CONFIG.encode(&mut out, &expected)?;
let actual = CONFIG.decode(&out[..])?;

assert_eq!(expected, actual);

Implementation details

Each field is prefix typed with a single byte tag that allows a receiver to figure out exactly how much should be skipped over.

Packed items are prefix-length encoded, and have a limited size. Its exact length is defined by MAX_INLINE_LEN and can be modified with Encoding::with_max_pack.