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Serialization Primitives

Metal Blockchain uses a simple, uniform, and elegant representation for all internal data. This document describes how primitive types are encoded on Metal Blockchain. Transactions are encoded in terms of these basic primitive types.

Byte​

Bytes are packed as-is into the message payload.

Example:

Packing:
    0x01
Results in:
    [0x01]

Short​

Shorts are packed in BigEndian format into the message payload.

Example:

Packing:
    0x0102
Results in:
    [0x01, 0x02]

Integer​

Integers are 32-bit values packed in BigEndian format into the message payload.

Example:

Packing:
    0x01020304
Results in:
    [0x01, 0x02, 0x03, 0x04]

Long Integers​

Long integers are 64-bit values packed in BigEndian format into the message payload.

Example:

Packing:
    0x0102030405060708
Results in:
    [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08]

IP Addresses​

IP addresses are represented as 16-byte IPv6 format, with the port appended into the message payload as a Short. IPv4 addresses are padded with 12 bytes of leading 0x00s.

IPv4 example:

Packing:
    "127.0.0.1:9650"
Results in:
    [
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0xff, 0xff, 0x7f, 0x00, 0x00, 0x01,
        0x25, 0xb2,
    ]

IPv6 example:

Packing:
    "[2001:0db8:ac10:fe01::]:12345"
Results in:
    [
        0x20, 0x01, 0x0d, 0xb8, 0xac, 0x10, 0xfe, 0x01,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x30, 0x39,
    ]

Fixed-Length Array​

Fixed-length arrays, whose length is known ahead of time and by context, are packed in order.

Byte array example:

Packing:
    [0x01, 0x02]
Results in:
    [0x01, 0x02]

Integer array example:

Packing:
    [0x03040506]
Results in:
    [0x03, 0x04, 0x05, 0x06]

Variable Length Array​

The length of the array is prefixed in Integer format, followed by the packing of the array contents in Fixed Length Array format.

Byte array example:

Packing:
    [0x01, 0x02]
Results in:
    [0x00, 0x00, 0x00, 0x02, 0x01, 0x02]

Int array example:

Packing:
    [0x03040506]
Results in:
    [0x00, 0x00, 0x00, 0x01, 0x03, 0x04, 0x05, 0x06]

String​

A String is packed similarly to a variable-length byte array. However, the length prefix is a short rather than an int. Strings are encoded in UTF-8 format.

Example:

Packing:
    "Avax"
Results in:
    [0x00, 0x04, 0x41, 0x76, 0x61, 0x78]