# Native model
[](https://crates.io/crates/native_model)
[](https://github.com/vincent-herlemont/native_model/actions/workflows/build_and_test_release.yml)
[](https://docs.rs/native_model)
[](LICENSE)
Add interoperability on the top of serialization formats like bincode, postcard etc.
See [concepts](#concepts) for more details.
## Goals
- **Interoperability**: Allows different applications to work together, even if they are using different
versions of the data model.
- **Data Consistency**: Ensure that we process the data expected model.
- **Flexibility**: You can use any serialization format you want. More details [here](#setup-your-serialization-format).
- **Performance**: A minimal overhead (encode: ~20 ns, decode: ~40 ps). More details [here](#performance).
## Usage
```text
Application 1 (DotV1) Application 2 (DotV1 and DotV2)
| |
Decode DotV1 | <--------------------------------| Encode DotV2 back to DotV1
| |
```
```rust
use native_model::native_model;
use serde::{Deserialize, Serialize};
#[derive(Deserialize, Serialize, PartialEq, Debug)]
#[native_model(id = 1, version = 1)]
struct DotV1(u32, u32);
#[derive(Deserialize, Serialize, PartialEq, Debug)]
#[native_model(id = 1, version = 2, from = DotV1)]
struct DotV2 {
name: String,
x: u64,
y: u64,
}
impl From<DotV1> for DotV2 {
fn from(dot: DotV1) -> Self {
DotV2 {
name: "".to_string(),
x: dot.0 as u64,
y: dot.1 as u64,
}
}
}
impl From<DotV2> for DotV1 {
fn from(dot: DotV2) -> Self {
DotV1(dot.x as u32, dot.y as u32)
}
}
// Application 1
let dot = DotV1(1, 2);
let bytes = native_model::encode(&dot).unwrap();
// Application 1 sends bytes to Application 2.
// Application 2
// We are able to decode the bytes directly into a new type DotV2 (upgrade).
let (mut dot, source_version) = native_model::decode::<DotV2>(bytes).unwrap();
assert_eq!(dot, DotV2 {
name: "".to_string(),
x: 1,
y: 2
});
dot.name = "Dot".to_string();
dot.x = 5;
// For interoperability, we encode the data with the version compatible with Application 1 (downgrade).
let bytes = native_model::encode_downgrade(dot, source_version).unwrap();
// Application 2 sends bytes to Application 1.
// Application 1
let (dot, _) = native_model::decode::<DotV1>(bytes).unwrap();
assert_eq!(dot, DotV1(5, 2));
```
- Full example [here](./tests_crate/tests/example/example_main.rs).
## Serialization format
You can use default serialization formats via the feature flags, like:
```toml
[dependencies]
native_model = { version = "0.1", features = ["bincode_2"] }
```
Each feature flag corresponds to a specific minor version of the serialization format. In order to avoid breaking
changes, the default serialization format is the oldest one.
- `bincode_1_3`: [bincode](https://docs.rs/bincode/1.3.3/bincode/) v1.3 (default)
- `bincode_2`: [bincode](https://docs.rs/bincode/2.0.0-rc.3/bincode/) v2.0.0-rc3
- `postcard_1_0`: [postcard](https://docs.rs/postcard/1.0.0/postcard/) v1.0
- `rpm_serde_1_3`: [rmp-serde](https://docs.rs/rmp-serde/1.3.0/rmp_serde/) v1.3
### Custom serialization format
Define a struct with the name you want. This struct must implement [`native_model::Encode`](https://docs.rs/native_model/latest/native_model/trait.Encode.html) and [`native_model::Decode`](https://docs.rs/native_model/latest/native_model/trait.Decode.html) traits.
Full examples:
- [bincode with encode/decode](./tests_crate/tests/example/custom_codec/bincode.rs)
- [bincode with serde](./tests_crate/tests/example/custom_codec/bincode_serde.rs)
Others examples, see the default implementations:
- [bincode v1.3](./src/codec/bincode_1_3.rs)
- [bincode v2.0 (rc)](./src/codec/bincode_2.rs)
- [postcard v1.0](./src/codec/postcard_1_0.rs)
- [rmp-serde v1.3](./src/codec/rmp_serde_1_3.rs)
### Notice
`native_model` provides implementations that rely on metadata-less formats and `serde`.
There are known issues with some `serde` advanced features such as:
- `#[serde(flatten)]`
- `#[serde(skip)]`
- `#[serde(skip_deserializing)]`
- `#[serde(skip_serializing)]`
- `#[serde(skip_serializing_if = "path")]`
- `#[serde(tag = "...")]`
- `#[serde(untagged)]`
Or types implementing similar strategies such as [`serde_json::Value`][serde_json_value].
The `rmp-serde` serialization format can optionally support them serializing structs as maps, the `RmpSerdeNamed` struct is provided to support this use-case.
[serde_json_value]: https://docs.rs/serde_json/latest/serde_json/enum.Value.html
## Data model
Define your model using the macro [`native_model`](file:///home/vincentherlemont/IdeaProjects/native_model/target/doc/native_model/attr.native_model.html).
Attributes:
- `id = u32`: The unique identifier of the model.
- `version = u32`: The version of the model.
- `with = type`: The serialization format that you use for the Encode/Decode implementation. Setup [here](#setup-your-serialization-format).
- `from = type`: Optional, the previous version of the model.
- `type`: The previous version of the model that you use for the From implementation.
- `try_from = (type, error)`: Optional, the previous version of the model with error handling.
- `type`: The previous version of the model that you use for the TryFrom implementation.
- `error`: The error type that you use for the TryFrom implementation.
```rust
use native_model::native_model;
use serde::{Deserialize, Serialize};
#[derive(Deserialize, Serialize, PartialEq, Debug)]
#[native_model(id = 1, version = 1)]
struct DotV1(u32, u32);
#[derive(Deserialize, Serialize, PartialEq, Debug)]
#[native_model(id = 1, version = 2, from = DotV1)]
struct DotV2 {
name: String,
x: u64,
y: u64,
}
// Implement the conversion between versions From<DotV1> for DotV2 and From<DotV2> for DotV1.
impl From<DotV1> for DotV2 {
fn from(dot: DotV1) -> Self {
DotV2 {
name: "".to_string(),
x: dot.0 as u64,
y: dot.1 as u64,
}
}
}
impl From<DotV2> for DotV1 {
fn from(dot: DotV2) -> Self {
DotV1(dot.x as u32, dot.y as u32)
}
}
#[derive(Deserialize, Serialize, PartialEq, Debug)]
#[native_model(id = 1, version = 3, try_from = (DotV2, anyhow::Error))]
struct DotV3 {
name: String,
cord: Cord,
}
#[derive(Deserialize, Serialize, PartialEq, Debug)]
struct Cord {
x: u64,
y: u64,
}
// Implement the conversion between versions From<DotV2> for DotV3 and From<DotV3> for DotV2.
impl TryFrom<DotV2> for DotV3 {
type Error = anyhow::Error;
fn try_from(dot: DotV2) -> Result<Self, Self::Error> {
Ok(DotV3 {
name: dot.name,
cord: Cord { x: dot.x, y: dot.y },
})
}
}
impl TryFrom<DotV3> for DotV2 {
type Error = anyhow::Error;
fn try_from(dot: DotV3) -> Result<Self, Self::Error> {
Ok(DotV2 {
name: dot.name,
x: dot.cord.x,
y: dot.cord.y,
})
}
}
```
## Codecs
`native_model` comes with several optional built-in serializer features available:
- [bincode 1.3](https://crates.io/crates/bincode/1.3.3)
- This is the default codec.
- **Warning: This codec may not work with all serde-derived types.**
- [bincode 2.0.0-rc.3](https://crates.io/crates/bincode/2.0.0-rc.3)
- Enable the `bincode_2` feature and use the `native_model::bincode_2::Bincode` attribute to have `native_db` use this crate for serializing & deserializing.
- **Warning: This codec may not work with all serde-derived types.**
- [postcard 1.0](https://crates.io/crates/postcard/1.0.8)
- Enable the `postcard_1_0` feature and use the `native_model::postcard_1_0::PostCard` attribute.
- **Warning: This codec may not work with all serde-derived types.**
- [rmp-serde 1.3](https://crates.io/crates/rmp-serde/1.3.0)
- Enable the `rmp_serde_1_3` feature and use the `native_model::rmp_serde_1_3::RmpSerde` attribute.
###### Codec example:
As example, to use `rmp-serde`:
1. In your project's `Cargo.toml` file, enable the `rmp_serde_1_3` feature for the `native_model` dependency.
- Be sure to check `crates.io` for the most recent [`native_model`](https://crates.io/crates/native_model) version number.
```toml
[dependencies]
serde = { version = "1.0", features = [ "derive" ] }
native_model = { version = "0.4", features = [ "rmp_serde_1_3" ] }
```
2. Assign the `rmp_serde_1_3` codec to your `struct` using the `with` attribute:
```rust
use native_model::native_model;
#[derive(Clone, Default, serde::Deserialize, serde::Serialize)]
#[native_model(id = 1, version = 1, with = native_model::rmp_serde_1_3::RmpSerde)]
struct MyStruct {
my_string: String,
// etc.
}
```
###### Additional reading
You may also want to check out [David Koloski](https://github.com/djkoloski)'s [Rust serialization benchmarks](https://github.com/djkoloski/rust_serialization_benchmark) for help selecting the codec (i.e. `bincode_1_3`, `rmp_serde_1_3`, etc.) that's best for your project.
## Status
Early development. Not ready for production.
## Concepts
In order to understand how the native model works, you need to understand the following concepts.
- **Identity**(`id`): The identity is the unique identifier of the model. It is used to identify the model and
prevent to decode a model into the wrong Rust type.
- **Version**(`version`) The version is the version of the model. It is used to check the compatibility between two
models.
- **Encode**: The encode is the process of converting a model into a byte array.
- **Decode**: The decode is the process of converting a byte array into a model.
- **Downgrade**: The downgrade is the process of converting a model into a previous version of the model.
- **Upgrade**: The upgrade is the process of converting a model into a newer version of the model.
Under the hood, the native model is a thin wrapper around serialized data. The `id` and the `version` are twice encoded with a [`little_endian::U32`](https://docs.rs/zerocopy/latest/zerocopy/byteorder/little_endian/type.U32.html). That represents 8 bytes, that are added at the beginning of the data.
``` text
+------------------+------------------+------------------------------------+
```
Full example [here](tests/example/example_define_model.rs).
## Performance
Native model has
been designed to have a minimal and constant overhead. That means that the overhead is the same
whatever the size of the data. Under the hood we use the [zerocopy](https://docs.rs/zerocopy/latest/zerocopy/) crate
to avoid unnecessary copies.
👉 To know the total time of the encode/decode, you need to add the time of your serialization format.
Resume:
- **Encode**: ~20 ns
- **Decode**: ~40 ps
| data size | encode time (ns) | decode time (ps) |
|:--------------------:|:---------------------:|:-----------------------:|
| 1 B | 19.769 ns - 20.154 ns | 40.526 ps - 40.617 ps |
| 1 KiB | 19.597 ns - 19.971 ns | 40.534 ps - 40.633 ps |
| 1 MiB | 19.662 ns - 19.910 ns | 40.508 ps - 40.632 ps |
| 10 MiB | 19.591 ns - 19.980 ns | 40.504 ps - 40.605 ps |
| 100 MiB | 19.669 ns - 19.867 ns | 40.520 ps - 40.644 ps |
Benchmark of the native model overhead [here](benches/overhead.rs).