Serialization Scheme

There are 2 serialization protocols used in NKN:

protobuf: used to serialize/deserialize data that do not require bit-wise identical serialized result, e.g. p2p messages.
our own serialization scheme: used to serialize/deserialize data that need to be identical on different versions and platforms, e.g. data that needs to be signed or stored in global state.

This document will only cover the second one.

The serialization scheme defines the serialization protocol for basic types. Serialization of a custom type is done by linearly serialize its fields, in the order defined in that type.

Serialization of Basic Type

Fixed Length Encoding

We define the following fixed length encoding functions:

uint8: WriteUint8
uint16: WriteUint16
uint32: WriteUint32
uint64: WriteUint64
bool: WriteBool
byte: WriteByte

The above functions are simply the LittleEndian encoding of the variable.

Variable Length Encoding

Unsigned Integer: WriteVarUint

if value < 0xfd             =>  WriteUint8(value)
else if value < 0xffff      =>  0xfd + WriteUint16(value)
else if value < 0xffffffff  =>  0xfe + WriteUint32(value)
else                        =>  0xff + WriteUint64(value)

Bytes: WriteVarBytes

WriteVarBytes(value) = WriteVarUint(len(value)) + value

String: WriteVarString

WriteVarString(value) = WriteVarBytes([]byte(value))