Custom Serialization

Hazelcast lets you plug a custom serializer to be used for serialization of objects.

Let's say you have a class CustomSerializableType and you would like to customize the serialization, since you may want to use an external serializer for only one class.

public class CustomSerializableType
{
    public string Value { get; set; }
}

Let's say your custom CustomSerializer will serialize CustomSerializableType.

public class CustomSerializer : IStreamSerializer<CustomSerializableType>
{
    public const int TypeId = 10;

    public void Write(IObjectDataOutput output, CustomSerializableType t)
    {
        var array = Encoding.UTF8.GetBytes(t.Value);
        output.WriteInt(array.Length);
        output.Write(array);
    }

    public CustomSerializableType Read(IObjectDataInput input)
    {
        var len = input.ReadInt();
        var array = new byte[len];
        input.Read(array, 0, array.Length);
        return new CustomSerializableType { Value = Encoding.UTF8.GetString(array) };
    }

    int ISerializer.TypeId => TypeId;

    public void Dispose()
    { }
}

Note that the serializer TypeId must be unique as Hazelcast will use it to lookup the CustomSerializer while it deserializes the object. Now the last required step is to register the CustomSerializer to the configuration.

Programmatic Configuration:

var hazelcastOptions = new HazelcastOptionsBuilder().Build();
hazelcastOptions.Serialization.Serializers.Add(
    new SerializerOptions {
        SerializedType = typeof(CustomSerializableType),
        Creator = () => new CustomSerializer()
    }
);

Declarative Configuration:

{
    "hazelcast": {
        "serialization": {
            "serializers": [
                {
                    "serializedTypeName": "CustomSerializableType",
                    "typeName": "CustomSerializer"
                }
            ]
        }
    }
}

From now on, Hazelcast will use CustomSerializer to serialize CustomSerializableType objects.