.. index:: single: mqtt .. _mqtt/0:

.. rst-class:: right

object

mqtt

Portable MQTT 5 client predicates using http_transport_protocol implementations.

| Availability: | logtalk_load(mqtt(loader))

| Author: Paulo Moura | Version: 1:0:0 | Date: 2026-08-08

| Compilation flags: | static, context_switching_calls

| Imports: | public :ref:`options <options/0>` | public :ref:`http_origin_site_helpers <http_origin_site_helpers/0>` | Uses: | :ref:`byte_order <byte_order/0>` | :ref:`list <list/0>` | :ref:`type <type/0>` | :ref:`url(Representation) <url/1>` | :ref:`user <user/0>`

| Remarks: | (none)

| Inherited public predicates: | Â :ref:`options_protocol/0::check_option/1` Â :ref:`options_protocol/0::check_options/1` Â :ref:`options_protocol/0::default_option/1` Â :ref:`options_protocol/0::default_options/1` Â :ref:`options_protocol/0::option/2` Â :ref:`options_protocol/0::option/3` Â :ref:`options_protocol/0::valid_option/1` Â :ref:`options_protocol/0::valid_options/1` Â

.. contents:: :local: :backlinks: top

Public predicates

.. index:: connect/3 .. _mqtt/0::connect/3:

connect/3 ^^^^^^^^^^^^^

Opens a transport connection for an MQTT or MQTT-over-TLS address and completes the MQTT CONNECT/CONNACK exchange.

| Compilation flags: | static

| Template: | connect(Address,Connection,Options) | Mode and number of proofs: | connect(+atom,--compound,+list) - one_or_error

| Exceptions: | Address is a variable: | instantiation_error | Address is neither a variable nor an atom: | type_error(atom,Address) | Address is an atom but not a valid MQTT address: | domain_error(mqtt_address,Address) | The server rejects the MQTT connection: | domain_error(mqtt_connack_reason_code,ReasonCode) | The server response is not a CONNACK packet: | domain_error(mqtt_packet,expected(connack,Packet))

---

.. index:: connect/4 .. _mqtt/0::connect/4:

connect/4 ^^^^^^^^^^^^^

Opens a transport connection to the given host and port and completes the MQTT CONNECT/CONNACK exchange. The scheme/1 option selects MQTT over TCP or TLS.

| Compilation flags: | static

| Template: | connect(Host,Port,Connection,Options) | Mode and number of proofs: | connect(+atom,+integer,--compound,+list) - one_or_error

| Exceptions: | Host or Port is a variable: | instantiation_error | Host is neither a variable nor an atom: | type_error(atom,Host) | Port is neither a variable nor an integer: | type_error(integer,Port) | Port is a negative integer: | domain_error(non_negative_integer,Port) | The server rejects the MQTT connection: | domain_error(mqtt_connack_reason_code,ReasonCode) | The server response is not a CONNACK packet: | domain_error(mqtt_packet,expected(connack,Packet))

---

.. index:: disconnect/2 .. _mqtt/0::disconnect/2:

disconnect/2 ^^^^^^^^^^^^^^^^

Closes an MQTT transport connection. MQTT DISCONNECT packet exchange will be layered on this transport operation.

| Compilation flags: | static

| Template: | disconnect(Connection,Options) | Mode and number of proofs: | disconnect(+compound,+list) - one_or_error

| Exceptions: | Options is a variable or a partial list: | instantiation_error | Options is neither a variable nor a list: | type_error(list,Options) | An element Option of the list Options is not a valid option: | domain_error(option,Option)

---

.. index:: connection_alive/1 .. _mqtt/0::connection_alive/1:

connection_alive/1 ^^^^^^^^^^^^^^^^^^^^^^

True if the term is an MQTT connection handle created by this object.

| Compilation flags: | static

| Template: | connection_alive(Connection) | Mode and number of proofs: | connection_alive(+compound) - zero_or_one

---

.. index:: packet_type/2 .. _mqtt/0::packet_type/2:

packet_type/2 ^^^^^^^^^^^^^^^^^

Table of MQTT control packet type names and numeric codes.

| Compilation flags: | static

| Template: | packet_type(Type,Code) | Mode and number of proofs: | packet_type(?atom,?integer) - zero_or_more

---

.. index:: reason_code/3 .. _mqtt/0::reason_code/3:

reason_code/3 ^^^^^^^^^^^^^^^^^

Table of MQTT reason code names and numeric codes by packet type.

| Compilation flags: | static

| Template: | reason_code(PacketType,Name,Code) | Mode and number of proofs: | reason_code(?atom,?atom,?integer) - zero_or_more

---

.. index:: publish/4 .. _mqtt/0::publish/4:

publish/4 ^^^^^^^^^^^^^

Publishes a message and waits synchronously for the required MQTT acknowledgement.

| Compilation flags: | static

| Template: | publish(Connection,Topic,Payload,Options) | Mode and number of proofs: | publish(+compound,+atom,+term,+list) - one_or_error

| Exceptions: | Topic is not a valid MQTT topic name: | domain_error(mqtt_topic_name,Topic) | Options contains an invalid packet identifier: | domain_error(mqtt_packet_identifier,PacketIdentifier) | Options contains an invalid QoS value: | domain_error(mqtt_qos,QoS) | The server response is not the expected acknowledgement packet: | domain_error(mqtt_packet,expected(Type-PacketIdentifier,Packet))

---

.. index:: subscribe/4 .. _mqtt/0::subscribe/4:

subscribe/4 ^^^^^^^^^^^^^^^

Subscribes to topic filters and waits synchronously for the matching SUBACK.

| Compilation flags: | static

| Template: | subscribe(Connection,TopicFilters,Result,Options) | Mode and number of proofs: | subscribe(+compound,+list,--list,+list) - one_or_error

| Exceptions: | TopicFilters is empty: | domain_error(mqtt_subscriptions,[]) | An element TopicFilter is not a valid MQTT topic filter: | domain_error(mqtt_topic_filter,TopicFilter) | Options contains invalid subscription options: | domain_error(mqtt_subscription_options,Byte) | The server response is not the expected SUBACK packet: | domain_error(mqtt_packet,expected(suback-PacketIdentifier,Packet))

---

.. index:: unsubscribe/4 .. _mqtt/0::unsubscribe/4:

unsubscribe/4 ^^^^^^^^^^^^^^^^^

Unsubscribes from topic filters and waits synchronously for the matching UNSUBACK.

| Compilation flags: | static

| Template: | unsubscribe(Connection,TopicFilters,Result,Options) | Mode and number of proofs: | unsubscribe(+compound,+list,--list,+list) - one_or_error

| Exceptions: | TopicFilters is empty: | domain_error(mqtt_topic_filters,[]) | An element TopicFilter is not a valid MQTT topic filter: | domain_error(mqtt_topic_filter,TopicFilter) | The server response is not the expected UNSUBACK packet: | domain_error(mqtt_packet,expected(unsuback-PacketIdentifier,Packet))

---

.. index:: receive/3 .. _mqtt/0::receive/3:

receive/3 ^^^^^^^^^^^^^

Receives the next MQTT packet.

| Compilation flags: | static

| Template: | receive(Connection,Message,Options) | Mode and number of proofs: | receive(+compound,--compound,+list) - one_or_error

| Exceptions: | The connection input ends before a complete packet is read: | domain_error(mqtt_packet_stream,unexpected_end_of_file) | The received bytes do not encode a valid MQTT packet: | domain_error(mqtt_packet,Packet)

---

.. index:: send_pingreq/1 .. _mqtt/0::send_pingreq/1:

send_pingreq/1 ^^^^^^^^^^^^^^^^^^

Sends a PINGREQ packet.

| Compilation flags: | static

| Template: | send_pingreq(Connection) | Mode and number of proofs: | send_pingreq(+compound) - one_or_error

| Exceptions: | The PINGREQ packet cannot be written to the connection output stream: | resource_error(mqtt_packet_stream)

---

.. index:: ping/2 .. _mqtt/0::ping/2:

ping/2 ^^^^^^^^^^

Sends PINGREQ and waits synchronously for PINGRESP.

| Compilation flags: | static

| Template: | ping(Connection,Options) | Mode and number of proofs: | ping(+compound,+list) - one_or_error

| Exceptions: | The connection input ends before a complete packet is read: | domain_error(mqtt_packet_stream,unexpected_end_of_file) | The server response is not a PINGRESP packet: | domain_error(mqtt_packet,expected(pingresp,Packet))

---

.. index:: encode_packet/2 .. _mqtt/0::encode_packet/2:

encode_packet/2 ^^^^^^^^^^^^^^^^^^^

Encodes a normalized MQTT packet term.

| Compilation flags: | static

| Template: | encode_packet(Packet,Bytes) | Mode and number of proofs: | encode_packet(+compound,--list(integer)) - one_or_error

| Exceptions: | Packet contains an invalid MQTT field value: | domain_error(mqtt_packet,Packet) | Packet has a packet type that is not yet supported: | resource_error(mqtt_packet_support)

---

.. index:: decode_packet/2 .. _mqtt/0::decode_packet/2:

decode_packet/2 ^^^^^^^^^^^^^^^^^^^

Decodes bytes into a normalized MQTT packet term.

| Compilation flags: | static

| Template: | decode_packet(Bytes,Packet) | Mode and number of proofs: | decode_packet(+list(integer),--compound) - one_or_error

| Exceptions: | Bytes contains an invalid MQTT packet encoding: | domain_error(mqtt_packet,Bytes) | Bytes contains bytes after the encoded packet: | domain_error(mqtt_packet_trailing_bytes,Rest) | Bytes encodes a packet type that is not yet supported: | resource_error(mqtt_packet_support)

---

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

.. index:: resolve_address/4 .. _mqtt/0::resolve_address/4:

resolve_address/4 ^^^^^^^^^^^^^^^^^^^^^

Resolves an MQTT address into scheme, host, and port.

| Compilation flags: | static

| Template: | resolve_address(Address,Scheme,Host,Port) | Mode and number of proofs: | resolve_address(+atom,-atom,-atom,-integer) - one_or_error

| Exceptions: | Address is a variable: | instantiation_error | Address is neither a variable nor an atom: | type_error(atom,Address) | Address is an atom but not a valid MQTT address: | domain_error(mqtt_address,Address) | Address contains an invalid authority: | domain_error(mqtt_address_authority,Authority)

---

.. index:: resolve_transport/3 .. _mqtt/0::resolve_transport/3:

resolve_transport/3 ^^^^^^^^^^^^^^^^^^^^^^^

Resolves an explicit or default transport object for the given MQTT scheme.

| Compilation flags: | static

| Template: | resolve_transport(Scheme,Transport0,Transport) | Mode and number of proofs: | resolve_transport(+atom,+object_identifier,-object_identifier) - one_or_error

| Exceptions: | Transport0 is a variable: | instantiation_error | Transport0 is neither a variable nor an existing object: | existence_error(object,Transport0) | Transport0 does not implement http_transport_protocol: | domain_error(http_transport_protocol_object,Transport0) | Transport0 does not support Scheme: | consistency_error(mqtt_options,scheme(Scheme),transport(Transport0))

---

.. index:: append_tls_transport/3 .. _mqtt/0::append_tls_transport/3:

append_tls_transport/3 ^^^^^^^^^^^^^^^^^^^^^^^^^^

Adds connection_transport(tls) to connection options for MQTT-over-TLS unless already specified.

| Compilation flags: | static

| Template: | append_tls_transport(Scheme,Options,OptionsWithTransport) | Mode and number of proofs: | append_tls_transport(+atom,+list,-list) - one_or_error

---

.. index:: write_packet/2 .. _mqtt/0::write_packet/2:

write_packet/2 ^^^^^^^^^^^^^^^^^^

Encodes and writes an MQTT packet to a binary output stream.

| Compilation flags: | static

| Template: | write_packet(Output,Packet) | Mode and number of proofs: | write_packet(+stream,+compound) - one_or_error

| Exceptions: | Packet is not a supported normalized MQTT packet: | resource_error(mqtt_packet_support) | Output cannot be written or flushed: | resource_error(mqtt_packet_stream)

---

.. index:: read_packet/2 .. _mqtt/0::read_packet/2:

read_packet/2 ^^^^^^^^^^^^^^^^^

Reads and decodes one MQTT packet from a binary input stream.

| Compilation flags: | static

| Template: | read_packet(Input,Packet) | Mode and number of proofs: | read_packet(+stream,--compound) - one_or_error

| Exceptions: | Input ends before a complete packet is read: | domain_error(mqtt_packet_stream,unexpected_end_of_file) | Input contains an invalid MQTT packet encoding: | domain_error(mqtt_packet,Packet)

---

.. index:: encode_uint8/2 .. _mqtt/0::encode_uint8/2:

encode_uint8/2 ^^^^^^^^^^^^^^^^^^

Encodes an unsigned 8-bit integer.

| Compilation flags: | static

| Template: | encode_uint8(Value,Bytes) | Mode and number of proofs: | encode_uint8(+integer,-list(integer)) - one_or_error

| Exceptions: | Value is a variable: | instantiation_error | Value is neither a variable nor an integer: | type_error(integer,Value) | Value is outside the unsigned 8-bit integer range: | domain_error(between(0,255),Value)

---

.. index:: decode_uint8/3 .. _mqtt/0::decode_uint8/3:

decode_uint8/3 ^^^^^^^^^^^^^^^^^^

Decodes an unsigned 8-bit integer.

| Compilation flags: | static

| Template: | decode_uint8(Bytes,Value,Rest) | Mode and number of proofs: | decode_uint8(+list(integer),-integer,-list(integer)) - one_or_error

| Exceptions: | The first element of Bytes is not a byte: | type_error(byte,Byte)

---

.. index:: encode_uint16/2 .. _mqtt/0::encode_uint16/2:

encode_uint16/2 ^^^^^^^^^^^^^^^^^^^

Encodes an unsigned 16-bit integer in network byte order.

| Compilation flags: | static

| Template: | encode_uint16(Value,Bytes) | Mode and number of proofs: | encode_uint16(+integer,-list(integer)) - one_or_error

| Exceptions: | Value is a variable: | instantiation_error | Value is neither a variable nor an integer: | type_error(integer,Value) | Value is outside the unsigned 16-bit integer range: | domain_error(between(0,65535),Value)

---

.. index:: decode_uint16/3 .. _mqtt/0::decode_uint16/3:

decode_uint16/3 ^^^^^^^^^^^^^^^^^^^

Decodes an unsigned 16-bit integer in network byte order.

| Compilation flags: | static

| Template: | decode_uint16(Bytes,Value,Rest) | Mode and number of proofs: | decode_uint16(+list(integer),-integer,-list(integer)) - one_or_error

| Exceptions: | One of the first two elements of Bytes is not a byte: | type_error(byte,Byte)

---

.. index:: encode_uint32/2 .. _mqtt/0::encode_uint32/2:

encode_uint32/2 ^^^^^^^^^^^^^^^^^^^

Encodes an unsigned 32-bit integer in network byte order.

| Compilation flags: | static

| Template: | encode_uint32(Value,Bytes) | Mode and number of proofs: | encode_uint32(+integer,-list(integer)) - one_or_error

| Exceptions: | Value is a variable: | instantiation_error | Value is neither a variable nor an integer: | type_error(integer,Value) | Value is outside the unsigned 32-bit integer range: | domain_error(between(0,4294967295),Value)

---

.. index:: decode_uint32/3 .. _mqtt/0::decode_uint32/3:

decode_uint32/3 ^^^^^^^^^^^^^^^^^^^

Decodes an unsigned 32-bit integer in network byte order.

| Compilation flags: | static

| Template: | decode_uint32(Bytes,Value,Rest) | Mode and number of proofs: | decode_uint32(+list(integer),-integer,-list(integer)) - one_or_error

| Exceptions: | One of the first four elements of Bytes is not a byte: | type_error(byte,Byte)

---

.. index:: encode_varint/2 .. _mqtt/0::encode_varint/2:

encode_varint/2 ^^^^^^^^^^^^^^^^^^^

Encodes an MQTT variable byte integer.

| Compilation flags: | static

| Template: | encode_varint(Value,Bytes) | Mode and number of proofs: | encode_varint(+integer,-list(integer)) - one_or_error

| Exceptions: | Value is a variable: | instantiation_error | Value is neither a variable nor an integer: | type_error(integer,Value) | Value is outside the MQTT variable byte integer range: | domain_error(between(0,268435455),Value)

---

.. index:: decode_varint/3 .. _mqtt/0::decode_varint/3:

decode_varint/3 ^^^^^^^^^^^^^^^^^^^

Decodes an MQTT variable byte integer, rejecting non-minimal encodings and overflows.

| Compilation flags: | static

| Template: | decode_varint(Bytes,Value,Rest) | Mode and number of proofs: | decode_varint(+list(integer),-integer,-list(integer)) - one_or_error

| Exceptions: | Bytes does not start with a valid, minimally encoded MQTT variable byte integer: | domain_error(mqtt_variable_byte_integer,Consumed)

---

.. index:: encode_utf8_string/2 .. _mqtt/0::encode_utf8_string/2:

encode_utf8_string/2 ^^^^^^^^^^^^^^^^^^^^^^^^

Encodes an MQTT UTF-8 encoded string with a two-byte length prefix.

| Compilation flags: | static

| Template: | encode_utf8_string(String,Bytes) | Mode and number of proofs: | encode_utf8_string(+atom,-list(integer)) - one_or_error

| Exceptions: | String is a variable: | instantiation_error | String is neither a variable nor atom: | type_error(atom,String) | String is not a valid MQTT UTF-8 string: | domain_error(mqtt_utf8_string,Codes)

---

.. index:: decode_utf8_string/3 .. _mqtt/0::decode_utf8_string/3:

decode_utf8_string/3 ^^^^^^^^^^^^^^^^^^^^^^^^

Decodes an MQTT UTF-8 encoded string with a two-byte length prefix.

| Compilation flags: | static

| Template: | decode_utf8_string(Bytes,String,Rest) | Mode and number of proofs: | decode_utf8_string(+list(integer),-atom,-list(integer)) - one_or_error

| Exceptions: | Bytes does not start with a valid MQTT UTF-8 string: | domain_error(mqtt_utf8_string,Codes)

---

.. index:: encode_binary_data/2 .. _mqtt/0::encode_binary_data/2:

encode_binary_data/2 ^^^^^^^^^^^^^^^^^^^^^^^^

Encodes MQTT binary data with a two-byte length prefix.

| Compilation flags: | static

| Template: | encode_binary_data(Data,Bytes) | Mode and number of proofs: | encode_binary_data(+list(integer),-list(integer)) - one_or_error

| Exceptions: | Data is not a list of bytes: | type_error(list(byte),Data) | Data is longer than 65535 bytes: | domain_error(between(0,65535),Length)

---

.. index:: decode_binary_data/3 .. _mqtt/0::decode_binary_data/3:

decode_binary_data/3 ^^^^^^^^^^^^^^^^^^^^^^^^

Decodes MQTT binary data with a two-byte length prefix.

| Compilation flags: | static

| Template: | decode_binary_data(Bytes,Data,Rest) | Mode and number of proofs: | decode_binary_data(+list(integer),-list(integer),-list(integer)) - one_or_error

| Exceptions: | The first two elements of Bytes do not encode a valid length: | type_error(byte,Byte)

---

.. index:: encode_utf8_string_pair/2 .. _mqtt/0::encode_utf8_string_pair/2:

encode_utf8_string_pair/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Encodes an MQTT UTF-8 string pair as two MQTT UTF-8 encoded strings.

| Compilation flags: | static

| Template: | encode_utf8_string_pair(Pair,Bytes) | Mode and number of proofs: | encode_utf8_string_pair(+compound,-list(integer)) - one_or_error

| Exceptions: | An element of Pair is not an atom: | type_error(atom,String) | An element of Pair is not a valid MQTT UTF-8 string: | domain_error(mqtt_utf8_string,Codes)

---

.. index:: decode_utf8_string_pair/3 .. _mqtt/0::decode_utf8_string_pair/3:

decode_utf8_string_pair/3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Decodes an MQTT UTF-8 string pair from two MQTT UTF-8 encoded strings.

| Compilation flags: | static

| Template: | decode_utf8_string_pair(Bytes,Pair,Rest) | Mode and number of proofs: | decode_utf8_string_pair(+list(integer),-compound,-list(integer)) - one_or_error

| Exceptions: | Bytes does not start with two valid MQTT UTF-8 strings: | domain_error(mqtt_utf8_string,Codes)

---

.. index:: encode_properties/2 .. _mqtt/0::encode_properties/2:

encode_properties/2 ^^^^^^^^^^^^^^^^^^^^^^^

Encodes an MQTT property list with its variable byte integer length prefix.

| Compilation flags: | static

| Template: | encode_properties(Properties,Bytes) | Mode and number of proofs: | encode_properties(+list,-list(integer)) - one_or_error

| Exceptions: | Properties is a variable or a partial list: | instantiation_error | Properties is neither a variable nor a list: | type_error(list,Properties) | An element Property is not a supported MQTT property: | domain_error(mqtt_property,Property)

---

.. index:: decode_properties/3 .. _mqtt/0::decode_properties/3:

decode_properties/3 ^^^^^^^^^^^^^^^^^^^^^^^

Decodes an MQTT property list and returns the remaining packet bytes.

| Compilation flags: | static

| Template: | decode_properties(Bytes,Properties,Rest) | Mode and number of proofs: | decode_properties(+list(integer),-list,-list(integer)) - one_or_error

| Exceptions: | Bytes does not contain the declared property bytes: | domain_error(mqtt_properties,Bytes) | Bytes contains an unknown property identifier: | domain_error(mqtt_property_identifier,Identifier)

---

.. index:: encode_property_list/2 .. _mqtt/0::encode_property_list/2:

encode_property_list/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^

Encodes MQTT properties without the property length prefix.

| Compilation flags: | static

| Template: | encode_property_list(Properties,Bytes) | Mode and number of proofs: | encode_property_list(+list,-list(integer)) - one_or_error

| Exceptions: | An element Property is not a supported MQTT property: | domain_error(mqtt_property,Property)

---

.. index:: decode_property_list/2 .. _mqtt/0::decode_property_list/2:

decode_property_list/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^

Decodes MQTT properties from a property body byte list.

| Compilation flags: | static

| Template: | decode_property_list(Bytes,Properties) | Mode and number of proofs: | decode_property_list(+list(integer),-list) - one_or_error

| Exceptions: | Bytes contains an unknown property identifier: | domain_error(mqtt_property_identifier,Identifier)

---

.. index:: encode_property/2 .. _mqtt/0::encode_property/2:

encode_property/2 ^^^^^^^^^^^^^^^^^^^^^

Encodes a single MQTT property.

| Compilation flags: | static

| Template: | encode_property(Property,Bytes) | Mode and number of proofs: | encode_property(+compound,-list(integer)) - one_or_error

| Exceptions: | Property is not a supported MQTT property: | domain_error(mqtt_property,Property) | Property contains an invalid value: | domain_error(mqtt_property_value,Name-Value)

---

.. index:: decode_property/3 .. _mqtt/0::decode_property/3:

decode_property/3 ^^^^^^^^^^^^^^^^^^^^^

Decodes a single MQTT property.

| Compilation flags: | static

| Template: | decode_property(Bytes,Property,Rest) | Mode and number of proofs: | decode_property(+list(integer),-compound,-list(integer)) - one_or_error

| Exceptions: | Bytes starts with an unknown property identifier: | domain_error(mqtt_property_identifier,Identifier) | Bytes contains an invalid property value: | domain_error(mqtt_property_value,Name-Value)

---

.. index:: mqtt_property/3 .. _mqtt/0::mqtt_property/3:

mqtt_property/3 ^^^^^^^^^^^^^^^^^^^

Table of MQTT property names, identifiers, and value types.

| Compilation flags: | static

| Template: | mqtt_property(Name,Identifier,Type) | Mode and number of proofs: | mqtt_property(?atom,?integer,?atom) - zero_or_more

---

.. index:: encode_fixed_header/4 .. _mqtt/0::encode_fixed_header/4:

encode_fixed_header/4 ^^^^^^^^^^^^^^^^^^^^^^^^^

Encodes an MQTT fixed header from packet type, flags, and remaining length.

| Compilation flags: | static

| Template: | encode_fixed_header(Type,Flags,RemainingLength,Bytes) | Mode and number of proofs: | encode_fixed_header(+atom,+integer,+integer,-list(integer)) - one_or_error

| Exceptions: | Type is not a supported MQTT packet type: | domain_error(mqtt_packet_type,Type) | Flags is invalid for Type: | domain_error(mqtt_fixed_header_flags,Type-Flags) | RemainingLength is outside the MQTT variable byte integer range: | domain_error(between(0,268435455),RemainingLength)

---

.. index:: decode_fixed_header/5 .. _mqtt/0::decode_fixed_header/5:

decode_fixed_header/5 ^^^^^^^^^^^^^^^^^^^^^^^^^

Decodes an MQTT fixed header into packet type, flags, remaining length, and remaining bytes.

| Compilation flags: | static

| Template: | decode_fixed_header(Bytes,Type,Flags,RemainingLength,Rest) | Mode and number of proofs: | decode_fixed_header(+list(integer),-atom,-integer,-integer,-list(integer)) - one_or_error

| Exceptions: | Bytes starts with an unsupported MQTT packet type: | domain_error(mqtt_packet_type,Code) | Bytes contains invalid fixed header flags: | domain_error(mqtt_fixed_header_flags,Type-Flags) | Bytes contains an invalid MQTT variable byte integer: | domain_error(mqtt_variable_byte_integer,Consumed)

---

Operators

(none)