docs/guide/rust/xlang-serialization.md

title: Xlang Serialization sidebar_position: 2 id: xlang_serialization license: | Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

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Apache Fory™ supports seamless data exchange across Java, Python, C++, Go, Rust, JavaScript/TypeScript, C#, Swift, Dart, Scala, and Kotlin.

Create an Xlang Runtime

Rust defaults to xlang mode with compatible schema evolution. Set the mode explicitly in xlang examples:

use fory::Fory;

// Use xlang mode
let mut fory = Fory::builder().xlang(true).build();

// Register types with consistent IDs across languages
fory.register::<MyStruct>(100)?;

// Or use name-based registration
fory.register_by_name::<MyStruct>("com.example", "MyStruct")?;

Type Registration for Xlang

Register by ID

For fast, compact serialization with consistent IDs across languages:

let mut fory = Fory::builder().xlang(true).build();

fory.register::<User>(100)?;  // Same ID in Java, Python, etc.

Register by Name

For more flexible type naming:

fory.register_by_name::<User>("com.example", "User")?;

Xlang Example

Rust (Serializer)

use fory::Fory;
use fory::ForyStruct;

#[derive(ForyStruct)]
struct Person {
    name: String,
    age: i32,
}

let mut fory = Fory::builder().xlang(true).build();

fory.register::<Person>(100)?;

let person = Person {
    name: "Alice".to_string(),
    age: 30,
};

let bytes = fory.serialize(&person)?;
// bytes can be deserialized by Java, Python, etc.

Java (Deserializer)

import org.apache.fory.*;
import org.apache.fory.config.*;

public class Person {
    public String name;
    public int age;
}

Fory fory = Fory.builder()
    .withXlang(true)
    .withRefTracking(true)
    .build();

fory.register(Person.class, 100);  // Same ID as Rust

Person person = (Person) fory.deserialize(bytesFromRust);

Python (Deserializer)

import pyfory
from dataclasses import dataclass

@dataclass
class Person:
    name: str
    age: pyfory.Int32

fory = pyfory.Fory(xlang=True, ref=True)
fory.register_type(Person, type_id=100)  # Same ID as Rust

person = fory.deserialize(bytes_from_rust)

Type Mapping

See xlang_type_mapping.md for complete type mapping across languages.

Common Type Mappings

Rust	Java	Python
`i32`	`int`	`int32`
`i64`	`long`	`int64`
`f32`	`float`	`float32`
`f64`	`double`	`float64`
`Float16`	`Float16`	`float16`
`BFloat16`	`BFloat16`	`bfloat16`
`String`	`String`	`str`
`Vec<T>`	`List<T>`	`List[T]`
`Vec<Float16>`	`Float16List`	`Float16Array`
`Vec<BFloat16>`	`BFloat16List`	`BFloat16Array`
`[Float16; N]`	`Float16List`	`Float16Array`
`[BFloat16; N]`	`BFloat16List`	`BFloat16Array`
`HashMap<K,V>`	`Map<K,V>`	`Dict[K,V]`
`Option<T>`	nullable `T`	`Optional[T]`

Lists and Dense Arrays

Rust Vec<T> maps to Fory list<T> by default for manual structs. Use an explicit array field attribute when the schema is dense array<T>.

Fory schema	Rust carrier and metadata
`list<int32>`	`Vec<i32>`
`array<bool>`	`#[fory(array)] Vec<bool>`
`array<int8>`	`#[fory(array)] Vec<i8>`
`array<int16>`	`#[fory(array)] Vec<i16>`
`array<int32>`	`#[fory(array)] Vec<i32>`
`array<int64>`	`#[fory(array)] Vec<i64>`
`array<uint8>`	`#[fory(array)] Vec<u8>`
`array<uint16>`	`#[fory(array)] Vec<u16>`
`array<uint32>`	`#[fory(array)] Vec<u32>`
`array<uint64>`	`#[fory(array)] Vec<u64>`
`array<float16>`	`#[fory(array)] Vec<Float16>`
`array<bfloat16>`	`#[fory(array)] Vec<BFloat16>`
`array<float32>`	`#[fory(array)] Vec<f32>`
`array<float64>`	`#[fory(array)] Vec<f64>`

Best Practices

Use consistent type IDs across all languages
Keep compatible mode for schema evolution
Register all types before serialization
Test cross-language compatibility during development