Transport

The message is defined as:

-record(z_msg_v1, {
    qos = 0 :: 0 | 1 | 2,
    dup = false :: boolean(),
    msg_id :: binary(),
    timestamp :: pos_integer(),
    content_type = ubf :: text | javascript | json | form | ubf | atom() | binary(),
    delegate = postback :: postback | mqtt | atom() | binary(),
    push_queue = page :: page | session | user,

    % Set by transports from user-agent to server
    session_id :: binary(),
    page_id :: binary(),

    % Payload data
    data :: any()
}).

The ack message is defined as:

-record(z_msg_ack, {
    qos = 1 :: 1 | 2,
    msg_id :: binary(),
    push_queue = page :: page | session | user,
    session_id :: binary(),
    page_id :: binary(),
    result :: any()
}).