emqtt

MQTT client library and command line tools implemented in Erlang that supports MQTT v5.0/3.1.1/3.1.

Getting started

As a Command Line Tool

Build

$ make

Once you've compiled successfully you will get a script called emqtt in _buile/emqtt/rel/emqtt/bin. We can see what emqtt can do with --help option:

$ ./emqtt --help
Usage: emqtt pub | sub [--help]

emqtt pub is used to publish a single message on a topic and exit. emqtt sub is used to subscribe to a topic and print the messages that it receives.

Command-line Syntax

Options can have both short (single character) and long (string) option names.

A short option can have the following syntax:

-e arg         Single option 'e', argument "arg"

A long option can have the following syntax:

--example=arg  Single option 'example', argument "arg"
--example arg  Single option 'example', argument "arg"

Publish

Synopsis

./emqtt pub [-h [<host>]] [-p <port>] [-I <iface>]
            [-V [<protocol_version>]] [-u <username>]
            [-P <password>] [-C <clientid>] [-k [<keepalive>]]
            [-t <topic>] [-q [<qos>]] [-r [<retain>]]
            [--help <help>] [--will-topic <will_topic>]
            [--will-payload <will_payload>]
            [--will-qos [<will_qos>]]
            [--will-retain [<will_retain>]]
            [--enable-websocket [<enable_websocket>]]
            [--enable-ssl [<enable_ssl>]]
            [--tls-version [<tls_version>]]
            [--CAfile <cafile>] [--cert <cert>]
            [--key <key>] [--payload <payload>]
            [--repeat [<repeat>]]
            [--repeat-delay [<repeat_delay>]]

Options

-h, --host

Specify the host to connect to, support for domain name and IP address. Defaults to localhost.

-p, --port

Specify the port to connect to. If not given, the default of 1883 for MQTT or 8883 for MQTT over TLS will be used.

-I, --iface

Specify the network interface or ip address to use.

-V, --protocol-version

Specify the MQTT protocol version used by the client. Can be v3.1, v3.1.1 and v5. Defaults to v5.

-u, --username

Specify the username that can be used by the broker for authentication and authorization.

-P, --password

Specify the password for the username.

-C, --clientid

Specify the client identifier. If not given, the client identifier in the format emqtt-<Hostname>-<Random Hexadecimal String> will be automatically generated by emqtt_cli.

-k, --keepalive

Specify the interval in seconds sending PINGREQ packets to the broker. Defaults to 300 seconds.

-t, --topic

Specify the MQTT topic you want to publish. If the topic beginning with $, you must use single quote(') to specify the topic rather than double quotes("). This is a required option.

-q, --qos

Specify the quality of service for the message. Can be 0, 1 and 2. Defaults to 0.

-r, --retain

Specify whether the message is a retained message. Defaults to false.

--payload

Specify the application message is to be published. This is a required option.

--repeat

Specify the number of times the message will be repeatedly published. Defaults to 1.

--repeat-count

Specify the number of seconds to wait after the previous message was delivered before publishing the next. Defaults to 0, it means to publish repeated messages as soon as the previous message is sent.

--will-topic

Specify the topic of the will message sent when the client disconnects unexpectedly.

--will-qos

Specify the quality of service of the will message. Defaults to 0. This must be used in conjunction with --will-topic.

--will-retain

Specify whether the will message is a retained message. Defaults to false. This must be used in conjunction with --will-topic.

--will-payload

Specify the application message that will be stored by the broker and sent out if this client disconnects unexpectedly. This must be used in conjunction with --will-topic.

--enable-websocket

Specify enable WebSocket transport or not. This option can't be used with --enable-ssl currently.

--enable-ssl

Specify enable SSL/TLS transport or not. This option can't be used with --enable-websocket currently.

--tls-version

Specify which TLS protocol version to use when communicating with the broker. Valid options are tlsv1.3, tlsv1.2, tlsv1.1 and tlsv1. Defaults to tlsv1.2.

--CAfile

Specify the path to a file containing PEM encoded CA certificates. This must be used in conjunction with --enable-ssl.

--cert

Specify the path to a file containing a PEM encoded certificate for this client, if required by the server. This must be used in conjunction with --enable-ssl.

--key

Specify the path to a file containing a PEM encoded private key for this client, if required by the server. This must be used in conjunction with --enable-ssl.

Examples

Publish a simple message over a TCP connection

$ ./emqtt pub -t "hello" --payload "hello world"
Client emqtt-zhouzibodeMacBook-Pro-4623faa14d8256e9cb95 sent CONNECT
Client emqtt-zhouzibodeMacBook-Pro-4623faa14d8256e9cb95 sent PUBLISH (Q0, R0, D0, Topic=hello, Payload=...(11 bytes))
Client emqtt-zhouzibodeMacBook-Pro-4623faa14d8256e9cb95 sent DISCONNECT

Publish a simple message over a TLS connection

$ ./emqtt pub --enable-ssl=true -t "hello" --payload "hello world" --CAfile=certs/cacert.pem --cert=certs/client-cert.pem --key=certs/client-key.pem
Client emqtt-zhouzibodeMacBook-Pro-cec9489c26e3ed7a38eb sent CONNECT
Client emqtt-zhouzibodeMacBook-Pro-cec9489c26e3ed7a38eb sent PUBLISH (Q0, R0, D0, Topic=hello, Payload=...(11 bytes))
Client emqtt-zhouzibodeMacBook-Pro-cec9489c26e3ed7a38eb sent DISCONNECT

Publish a message repeatedly over a WebSocket connection

$ ./emqtt pub --enable-websocket=true -p 8083 -t "hello" --payload "hello world"
Client emqtt-zhouzibodeMacBook-Pro-1e4677ab46cecf1298ac sent CONNECT
Client emqtt-zhouzibodeMacBook-Pro-1e4677ab46cecf1298ac sent PUBLISH (Q0, R0, D0, Topic=hello, Payload=...(11 bytes))
Client emqtt-zhouzibodeMacBook-Pro-1e4677ab46cecf1298ac sent DISCONNECT

Subscribe

Synopsis

./emqtt sub [-h [<host>]] [-p <port>] [-I <iface>]
            [-V [<protocol_version>]] [-u <username>]
            [-P <password>] [-C <clientid>] [-k [<keepalive>]]
            [-t <topic>] [-q [<qos>]] [--help <help>]
            [--will-topic <will_topic>]
            [--will-payload <will_payload>]
            [--will-qos [<will_qos>]]
            [--will-retain [<will_retain>]]
            [--enable-websocket [<enable_websocket>]]
            [--enable-ssl [<enable_ssl>]]
            [--tls-version [<tls_version>]]
            [--CAfile <cafile>] [--cert <cert>]
            [--key <key>]
            [--retain-as-publish [<retain_as_publish>]]
            [--retain-handling [<retain_handling>]]

Options

-h, --host

Examples

Build Non-shared Subscription and Recv "hello world"

$ ./emqtt sub -t "hello"
Client emqtt-zhouzibodeMacBook-Pro-1686fee6fdb99f674f2c sent CONNECT
Client emqtt-zhouzibodeMacBook-Pro-1686fee6fdb99f674f2c subscribed to hello
hello world

Build Shared Subscription and Recv "hello world"

$ ./emqtt sub -t '$share/group/hello'
Client emqtt-zhouzibodeMacBook-Pro-288e65bb3f4013d30249 sent CONNECT
Client emqtt-zhouzibodeMacBook-Pro-288e65bb3f4013d30249 subscribed to $share/group/hello
hello world

As a Dependency Library

Add to rebar3 project

Add to rebar.config

...
{deps, [{emqtt, {git, "https://github.com/emqx/emqtt", {tag, "v1.2.0"}}}]}.
...

Build

$ rebar3 compile

Data Types

option()

option() = {name, atom()} |
           {owner, pid()} |
           {host, host()} |
           {port, inet:port_number()} |
           {tcp_opts, [gen_tcp:option()]} |
           {ssl, boolean()} |
           {ssl_opts, [ssl:ssl_option()]} |
           {ws_path, string()} |
           {connect_timeout, pos_integer()} |
           {bridge_mode, boolean()} |
           {clientid, iodata()} |
           {clean_start, boolean()} |
           {username, iodata()} |
           {password, iodata()} |
           {proto_ver, v3 | v4 | v5} |
           {keepalive, non_neg_integer()} |
           {max_inflight, pos_integer()} |
           {retry_interval, pos_integer()} |
           {will_topic, iodata()} |
           {will_payload, iodate()} |
           {will_retain, boolean()} |
           {will_qos, qos()} |
           {will_props, properties()} |
           {auto_ack, boolean()} |
           {ack_timeout, pos_integer()} |
           {force_ping, boolean()} |
           {properties, properties()}

client()

client() = pid() | atom()

host()

host() = inet:ip_address() | inet:hostname()

properties()

properties() = #{'Payload-Format-Indicator' => 0..1,
                 'Message-Expiry-Interval' => 0..16#FFFFFFFF,
                 'Content-Type' => binary(),
                 'Response-Topic' => binary(),
                 'Correlation-Data' => binary(),
                 'Subscription-Identifier' => 0..16#7FFFFFFF,
                 'Session-Expiry-Interval' => 0..16#FFFFFFFF,
                 'Assigned-Client-Identifier' => binary(),
                 'Server-Keep-Alive' => 0..16#FFFF,
                 'Authentication-Method' => binary(),
                 'Authentication-Data' => binary(),
                 'Request-Problem-Information' => 0..1,
                 'Will-Delay-Interval' => 0..16#FFFFFFFF,
                 'Request-Response-Information' => 0..1,
                 'Response-Information' => binary(),
                 'Server-Reference' => binary(),
                 'Reason-String' => binary(),
                 'Receive-Maximum' => 1..16#FFFF,
                 'Topic-Alias-Maximum' => 0..16#FFFF,
                 'Topic-Alias' => 1..16#FFFF,
                 'Maximum-QoS' => 0..1,
                 'Retain-Available' => 0..1,
                 'User-Property' => [{binary(), binary()}],
                 'Maximum-Packet-Size' => 1..16#FFFFFFFF,
                 'Wildcard-Subscription-Available' => 0..1,
                 'Subscription-Identifier-Available' => 0..1,
                 'Shared-Subscription-Available' => 0..1}

qos()

qos() = 0 | 1 | 2

qos_name()

qos_name() = qos0 | at_most_once |
             qos1 | at_least_once |
             qos2 | exactly_once

topic()

topic() = binary()

payload()

payload() = iodata()

packet_id()

packet_id() = 0..16#FFFF

subopt()

subopt() = {rh, 0 | 1 | 2} |
           {rap, boolean()} |
           {nl, boolean()} |
           {qos, qos() | qos_name()}

pubopt()

pubopt() = {retain, boolean()} |
           {qos, qos() | qos_name()}

reason_code()

reason_code() = 0..16#FF

Exports

emqtt:start_link() -> {ok, Pid} | ignore | {error, Reason}

emqtt:start_link(Options) -> {ok, Pid} | ignore | {error, Reason}

Types

Pid = pid()

Reason = term()

Options = [option()]

Start MQTT client process with specified options. Options will be used in connecting and running.

The following options are available:

{name, Name}

If a name is provided, the gen_statem will be registered with this name. For details see the documentation for the first argument of gen_statem:start_link/4.

{owner, Pid}

Client process will send messages like {diconnected, ReasonCode, Properties} to the owner process.

{host, Host}

The host of the MQTT server to be connected. Host can be a hostname or an IP address. Defaults to localhost

{port, Port}

The port of the MQTT server to be connected. If not given, the default of 1883 for MQTT or 8883 for MQTT over TLS will be used.

{tcp_opts, Options}

Additional options for gen_tcp:connect/3.

{ssl, boolean()}

Enable SSL/TLS transport or not. Defaults to false.

{ssl_opts, Options}

Additional options for ssl:connect/3.

{ws_path, Path}

Path to the resource. Defaults to /mqtt

{connect_timeout, Timeout}

The maximum time to wait to connect to the server and the server returns a CONNACK. Defaults to 60s.

{bridge_mode, boolean()}

Enable bridge mode or not. Defaults to false.

{clientid, ClientID}

Specify the client identifier. If not given, the client identifier will use the value assigned by the server in MQTT v5 or be automatically generated by internal code in MQTT v3.1/v3.1.1.

{clean_start, CleanStart}

Whether the server should discard any existing session and start a new session. Defaults to true.

{username, Username}

Username used by the server for authentication and authorization.

{password, Password}

Password used by the server for authentication and authorization.

{proto_ver, ProtocolVersion}

MQTT protocol version. Defaults to v4.

{keepalive, Keepalive}

Maximum time interval that is permitted to elapse between the point at which the Client finishes transmitting one MQTT Control Packet and the point it starts sending the next. It will be replaced by server keep alive returned from MQTT server.

{max_inflight, MaxInflight}

Max number of QoS 1 and QoS 2 packets in flight. In other words, the number of packets that were sent but not yet acked. Defaults to infinity, means no limit.

{retry_interval, RetryInterval}

Interval to retry sending packets that have been sent but not received a response. Defaults to 30s.

{will_topic, WillTopic}

Topic of will message.

{will_payload, WillPayload}

Payload of will message.

{will_retain, WillRetain}

Whether the server should publish the will message as a retained message. Defaults to false.

{will_qos, WillQoS}

QoS of will message. Defaults to 0.

{will_props, WillProperties}

Properties of will message.

{auto_ack, boolean()}

If true (the default), cliean process will automatically send ack packet like PUBACK when it receives a packet from the server. If false, application decides what to do.

{ack_timeout, AckTimeout}

Maximum time to wait for a reply message. Defaults to 30s.

{force_ping, boolean()}

If false (the default), if any other packet is sent during keep alive interval, the ping packet will not be sent this time. If true, the ping packet will be sent every time.

{properties, Properties}

Properties of CONNECT packet.

emqtt:connect(Client) -> {ok, Properties} | {error, Reason}

Types

Client = client()

Properties = properties()

Reason = timeout | inet:posix() | any()

Connect to the MQTT server over TCP or TLS and send a CONNECT packet with the options specified in start_link/1, 2. Client must be a pid returned from start_link/1, 2 or a name specified in start_link/1, 2.

Returns:

{ok, Properties} if a MQTT connection is established. Properties is propterties in CONNACK packet returned from MQTT server.
{error, timeout} if connection can't be established within the specified time
{error, inet:posix()} A POSIX error value if something else goes wrong.

emqtt:ws_connect(Client) -> {ok, Properties} | {error, Reason}

Types

Same as emqtt:connect/1

Connect to the MQTT server over Websocket and send a CONNECT packet with the options specified in start_link/1, 2. Client must be a pid returned from start_link/1, 2 or a name specified in start_link/1, 2.

emqtt:disconnect(Client) -> ok | {error, Reason}

emqtt:disconnect(Client, ReasonCode) -> ok | {error, Reason}

emqtt:disconnect(Client, ReasonCode, Properties) -> ok | {error, Reason}

Types

Client = client()

ReasonCode = reason_code()

Properties = properties()

Reason = closed | inet:posix()

Send a DISCONNECT packet to the MQTT server. ReasonCode specifies a MQTT reason code for DISCONNECT packet, defaults to 0 meaning normal disconnection. Properties specifies properties for DISCONNECT packet, defaults to #{} meaning no properties are attached.

emqtt:ping(Client) -> pong | {error, Reason}

Types

Client = client()

Reason = ack_timeout

Send a PINGREQ packet to the MQTT server. If PINGRESP packet is received from the server within the timeout period, pong is returned. If not, {error, ack_timeout} is returned.

emqtt:subscribe(Client, Properties, Subscriptions) -> {ok, Properties, ReasonCodes} | {error, Reason})

Types

Client = client()

Properties = properties()

Subscriptions = [{topic(), [subopt()]}]

ReasonCodes = [reason_code()]

Reason = term()

Send a SUBSCRIBE packet to the MQTT server. Properties specifies properties for SUBSCRIBE packet, defaults to #{} meaning no properties are attached. Subscriptions specifies pairs of topic filter and subscription options. The topic filter is requried, the subscription options can be [], equivalent to [{rh, 0}, {rap, 0}, {nl, 0}, {qos, 0}].

emqtt:unsubscribe(Client, Properties, Topics) -> {ok, Properties, ReasonCodes} | {error, Reason})

Types

Client = client()

Properties = properties()

Topics = [topic()]

ReasonCodes = [reason_code()]

Reason = term()

Send a UNSUBSCRIBE packet to the MQTT server. Properties specifies properties for SUBSCRIBE packet, defaults to #{} meaning no properties are attached. Topics specifies a list of topic filter with at least one topic filter.

emqtt:publish(Client, Topic, Properties, Payload, PubOpts) -> ok | {ok, PacketId} | {error, Reason})

Types

Client = client()

Topic = topic()

Properties = properties()

Payload = payload()

PubOpts = [pubopt()]

PacketId = packet_id()

Reason = term()

Send a PUBLISH packet to the MQTT server. Topic, Properties and Payload specify topic, properties and payload for PUBLISH packet. PubOpts specifies qos and retain flag for PUBLISH packet, defaults to [], equivalent to [{qos, 0}, {retain, false}].

Returns:

ok Ii a QoS 0 packet is sent.
{ok, PacketId} if a QoS 1/2 packet is sent, the packet identifier will be returned.
{error, Reason} if something goes wrong.

emqtt:puback(Client, PacketId) -> ok

emqtt:puback(Client, PacketId, ReasonCode) -> ok

emqtt:puback(Client, PacketId, ReasonCode, Properties) -> ok

Types

Client = client()

PacketId = packet_id()

ReasonCode = reason_code()

Properties = properties()

Send a PUBACK packet to the MQTT server. PacketId, ReasonCode and Properties specify packet identifier, reason code and properties for PUBACK packet.

emqtt:pubrec(Client, PacketId) -> ok

emqtt:pubrec(Client, PacketId, ReasonCode) -> ok

emqtt:pubrec(Client, PacketId, ReasonCode, Properties) -> ok

Types

Same as emqtt:puback/2, 3, 4.

Send a PUBREC packet to the MQTT server. PacketId, ReasonCode and Properties specify packet identifier, reason code and properties for PUBREC packet.

emqtt:pubrel(Client, PacketId) -> ok

emqtt:pubrel(Client, PacketId, ReasonCode) -> ok

emqtt:pubrel(Client, PacketId, ReasonCode, Properties) -> ok

Types

Same as emqtt:puback/2, 3, 4.

Send a PUBREL packet to the MQTT server. PacketId, ReasonCode and Properties specify packet identifier, reason code and properties for PUBREL packet.

emqtt:pubcomp(Client, PacketId) -> ok

emqtt:pubcomp(Client, PacketId, ReasonCode) -> ok

emqtt:pubcomp(Client, PacketId, ReasonCode, Properties) -> ok

Types

Same as emqtt:puback/2, 3, 4.

Send a PUBCOMP packet to the MQTT server. PacketId, ReasonCode and Properties specify packet identifier, reason code and properties for PUBCOMP packet.

emqtt:subscriptions(Client) -> Subscriptions

Types

Client = client()

Subscriptions = [{topic(), [subopt()]}]

Return all subscriptions.

emqtt:stop(Client) -> ok

Types

Client = client()

Stop a client process.

emqtt:pause(Client) -> ok

Types

Client = client()

Pause the client process. The paused client process will ignore all PUBLISH packets received and not send PINGREQ packet if force_ping is set to false.

emqtt:resume(Client) -> ok

Types

Client = client()

Resume a client process from a paused state.

Examples

{ok, ConnPid} = emqtt:start_link([{clientid, ClientId}]).
{ok, _Props} = emqtt:connect(ConnPid).

SubOpts = [{qos, 1}].
{ok, _Props, _ReasonCodes} = emqtt:subscribe(ConnPid, #{}, [{<<"hello">>, SubOpts}]).

ok = emqtt:publish(ConnPid, <<"hello">>, #{}, <<"Hello World!">>, [{qos, 0}]).
{ok, _PktId} = emqtt:publish(ConnPid, <<"hello">>, #{}, <<"Hello World!">>, [{qos, 1}]).

receive
    {disconnect, ReasonCode, Properties} ->
        io:format("Recv a DISONNECT packet - ReasonCode: ~p, Properties: ~p~n", [ReasonCode, Properties]);
    {publish, PUBLISH} ->
        io:format("Recv a PUBLISH packet: ~p~n", [PUBLISH]);
    {puback, {PacketId, ReasonCode, Properties}} ->
        io:format("Recv a PUBACK packet - PacketId: ~p, ReasonCode: ~p, Properties: ~p~n", [PacketId, ReasonCode, Properties])
end.

{ok, _Props, _ReasonCode} = emqtt:unsubscribe(ConnPid, #{}, <<"hello">]).

ok = emqtt:disconnect(ConnPid).
ok = emqtt:stop(ConnPid).

License

Apache License Version 2.0

Author

EMQ X Team.

jjzhang166 / emqtt

emqtt

Getting started

As a Command Line Tool

Build

Command-line Syntax

Publish

Synopsis

Options

Examples

Subscribe

Synopsis

Options

Examples

As a Dependency Library

Add to rebar3 project

Build

Data Types

Exports

Examples

License

Author

简介

发行版

贡献者

近期动态

jjzhang166 / emqtt .gitee-modal { width: 500px !important; }

emqtt

Getting started

As a Command Line Tool

Build

Command-line Syntax

Publish

Synopsis

Options

Examples

Subscribe

Synopsis

Options

Examples

As a Dependency Library

Add to rebar3 project

Build

Data Types

Exports

Examples

License

Author

简介

发行版

贡献者

近期动态

搜索帮助

jjzhang166 / emqtt