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Basic Serialization

This page covers typed serialization APIs in the default xlang mode for Apache Fory™ C#.

Object Graph Serialization​

Use [ForyStruct] on your classes/structs and register them before use.

using Apache.Fory;

[ForyStruct]
public sealed class Address
{
    public string Street { get; set; } = string.Empty;
    public int Zip { get; set; }
}

[ForyStruct]
public sealed class Person
{
    public long Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public string? Nickname { get; set; }
    public List<int> Scores { get; set; } = [];
    public List<Address> Addresses { get; set; } = [];
}

Fory fory = Fory.Builder().Build();
fory.Register<Address>(100);
fory.Register<Person>(101);

Person person = new()
{
    Id = 42,
    Name = "Alice",
    Nickname = null,
    Scores = [10, 20, 30],
    Addresses = [new Address { Street = "Main", Zip = 94107 }],
};

byte[] payload = fory.Serialize(person);
Person decoded = fory.Deserialize<Person>(payload);

Class Inheritance​

An annotated class includes the supported members declared by its annotated base classes in one flattened schema. Annotate every class in the hierarchy directly; [ForyStruct] is not inherited.

[ForyStruct]
public abstract class Entity
{
    [ForyField(1)]
    private long _id;

    public long Id => _id;
}

[ForyStruct]
public sealed class User : Entity
{
    [ForyField(2)]
    public string Name { get; set; } = string.Empty;
}

Public and assembly-accessible mutable members are included automatically. Private, protected-only, and otherwise inaccessible fields or properties must carry [ForyField] on the class that declares them. Abstract annotated bases publish schema information for concrete descendants but are not registered or serialized as roots.

The concrete derived type is still registered once:

fory.Register<User>(102);

For a base class from an unmodifiable package, declare its fields explicitly as described in External Types.

Typed API​

Serialize / Deserialize with byte arrays​

byte[] payload = fory.Serialize(value);
MyType decoded = fory.Deserialize<MyType>(payload);

Deserialize from ReadOnlySpan<byte>​

ReadOnlySpan<byte> span = payload;
MyType decoded = fory.Deserialize<MyType>(span);

Dynamic Payloads via Generic Object API​

When the compile-time type is unknown or heterogeneous, use the generic API with object?.

Dictionary<object, object?> value = new()
{
    ["k1"] = 7,
    [2] = "v2",
    [true] = null,
};

byte[] payload = fory.Serialize<object?>(value);
object? decoded = fory.Deserialize<object?>(payload);

Dynamic maps normally decode as Dictionary<object, object?> when they have no null key. If the payload uses reference tracking for the dynamic map itself, C# returns NullableKeyDictionary<object, object?> so nested references and null keys point to the decoded map owner.

Buffer Writer API​

Serialize directly into IBufferWriter<byte> targets.

using System.Buffers;

ArrayBufferWriter<byte> writer = new();
fory.Serialize(writer, value);

ArrayBufferWriter<byte> dynamicWriter = new();
fory.Serialize<object?>(dynamicWriter, value);

Notes​

  • Reuse the same Fory or ThreadSafeFory instance for better performance.
  • Primitive types and collections do not require user registration.
  • Register user types handled by [ForyStruct], [ForyEnum], [ForyUnion], external structural serializers, or custom serializers explicitly.

Cross-Language Interoperability​

The default xlang format is shared by all Fory implementations. The following sections cover its cross-language type mapping, type identity, and interoperability requirements.

Apache Fory™ C# supports xlang serialization with other Fory implementations.

Xlang Configuration​

C# always writes and reads the xlang frame header. There is no mode switch, so interoperability code only needs to configure the remaining settings such as compatibility mode and reference tracking.

Fory fory = Fory.Builder()
    .Build();

Register with Stable IDs​

[ForyStruct]
public sealed class Person
{
    public string Name { get; set; } = string.Empty;
    public int Age { get; set; }
}

Fory fory = Fory.Builder()
    .Build();

fory.Register<Person>(100);

Use the same ID mapping on all languages.

Third-party classes, structs, and enums can use external-type serialization. Register the target type, not its local serializer declaration, with the same ID or name used by the other language peers.

Register by Name​

fory.Register<Person>("com.example.Person");

Xlang Example​

C# (Serializer)​

Person person = new() { Name = "Alice", Age = 30 };
byte[] payload = fory.Serialize(person);

Java (Deserializer)​

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

fory.register(Person.class, 100);
Person value = (Person) fory.deserialize(payloadFromCSharp);

Python (Deserializer)​

import pyfory

fory = pyfory.Fory(xlang=True, ref=True)
fory.register_type(Person, type_id=100)
value = fory.deserialize(payload_from_csharp)

Type Mapping Reference​

See cross-language interoperability guide for complete mapping.

For reduced-precision numeric payloads, use Half / Half[] or List<Half> for xlang float16, and BFloat16 / BFloat16[] or List<BFloat16> for xlang bfloat16.

Lists and Dense Arrays​

C# List<T> maps to Fory list<T>. Use the schema marker Apache.Fory.Schema.Types.Array<T> when a field is dense array<T>.

Fory schemaC# schema marker sketch
list<int32>S.List<S.Int32>
array<bool>S.Array<S.Bool>
array<int8>S.Array<S.Int8>
array<int16>S.Array<S.Int16>
array<int32>S.Array<S.Int32>
array<int64>S.Array<S.Int64>
array<uint8>S.Array<S.UInt8>
array<uint16>S.Array<S.UInt16>
array<uint32>S.Array<S.UInt32>
array<uint64>S.Array<S.UInt64>
array<float16>S.Array<S.Float16>
array<bfloat16>S.Array<S.BFloat16>
array<float32>S.Array<S.Float32>
array<float64>S.Array<S.Float64>

Interoperability Best Practices​

  1. Keep type IDs stable and documented.
  2. Keep compatible mode enabled for rolling upgrades.
  3. Register all user types on both read/write peers.
  4. Validate integration with real payload round trips.