Behaviour for payload codecs.

Payload codecs handle encoding and decoding of MQTT message payloads.

Built-in Codecs

• MqttX.Payload.Raw - Pass-through, no encoding
• MqttX.Payload.JSON - JSON encoding via Jason
• MqttX.Payload.Protobuf - Protocol Buffers via Protox

Custom Codec Example

defmodule MyCodec do
  @behaviour MqttX.Payload

  @impl true
  def encode(term) do
    {:ok, :erlang.term_to_binary(term)}
  end

  @impl true
  def decode(binary) do
    {:ok, :erlang.binary_to_term(binary)}
  end
end