Protobuf / JSON / etc

If you want to use Protobuf, JSON, or whatever serialization methods, it is also quite easy: Since flutter_rust_bridge supports complicated types, it surely supports the simple Vec<u8>/String.

For example, the code below uses JSON to serialize the arguments/results:

// Dart
var result = jsonDecode(await api.f(a: jsonEncode({"x": [100, 200, "what"], "y": "hello"})));

// Rust
pub fn f(a: String) -> Result<String> {
    let arg = serde_json::from_str(&a)?;
    Ok(json!({"some": "result", "is": [42]}).to_string())
}

If you want to even automatically generate those serialization calls (jsonEncode, jsonDecode, etc), feel free to create an issue to tell me! (I usually reply quickly within hours)

Drawbacks

However, it is generally preferred to avoid Protobuf/JSON, and use the flutter_rust_bridge features directly.

On one hand, by doing so, we can use all features that flutter_rust_bridge provides, which is a long list ;)

On the other hand, for example, please refer to https://github.com/flutter/flutter/issues/60758 to see why the official Flutter chooses to write a custom serialization protocol, instead of using Protobuf. (P.S. In flutter_rust_bridge, the SSE codec is serialization-based which is like the Flutter protocol in that text, and the CST/DCO codecs mimic how humans write C glue code in the standard way. Both can be freely configured and used.)