ESP-MQTT ======== Overview -------- ESP-MQTT is an implementation of MQTT protocol client (MQTT is a lightweight publish/subscribe messaging protocol). Features -------- * Supports MQTT over TCP, SSL with mbedtls, MQTT over Websocket, MQTT over Websocket Secure. * Easy to setup with URI * Multiple instances (Multiple clients in one application) * Support subscribing, publishing, authentication, last will messages, keep alive pings and all 3 QoS levels (it should be a fully functional client). Application Example ------------------- * :example:`protocols/mqtt/tcp`: MQTT over tcp, default port 1883 * :example:`protocols/mqtt/ssl`: MQTT over tcp, default port 8883 * :example:`protocols/mqtt/ssl_psk`: MQTT over tcp using pre-shared keys for authentication, default port 8883 * :example:`protocols/mqtt/ws`: MQTT over Websocket, default port 80 * :example:`protocols/mqtt/wss`: MQTT over Websocket Secure, default port 443 Configuration ------------- URI ^^^ - Curently support ``mqtt``, ``mqtts``, ``ws``, ``wss`` schemes - MQTT over TCP samples: - ``mqtt://mqtt.eclipse.org``: MQTT over TCP, default port 1883: - ``mqtt://mqtt.eclipse.org:1884`` MQTT over TCP, port 1884: - ``mqtt://username:password@mqtt.eclipse.org:1884`` MQTT over TCP, port 1884, with username and password - MQTT over SSL samples: - ``mqtts://mqtt.eclipse.org``: MQTT over SSL, port 8883 - ``mqtts://mqtt.eclipse.org:8884``: MQTT over SSL, port 8884 - MQTT over Websocket samples: - ``ws://mqtt.eclipse.org:80/mqtt`` - MQTT over Websocket Secure samples: - ``wss://mqtt.eclipse.org:443/mqtt`` - Minimal configurations: .. code:: c const esp_mqtt_client_config_t mqtt_cfg = { .uri = "mqtt://mqtt.eclipse.org", // .user_context = (void *)your_context }; esp_mqtt_client_handle_t client = esp_mqtt_client_init(&mqtt_cfg); esp_mqtt_client_register_event(client, ESP_EVENT_ANY_ID, mqtt_event_handler, client); esp_mqtt_client_start(client); - Note: By default mqtt client uses event loop library to post related mqtt events (connected, subscribed, published, etc.) SSL ^^^ - Get certificate from server, example: ``mqtt.eclipse.org`` ``openssl s_client -showcerts -connect mqtt.eclipse.org:8883 /dev/null|openssl x509 -outform PEM >mqtt_eclipse_org.pem`` - Check the sample application: ``examples/mqtt_ssl`` - Configuration: .. code:: c const esp_mqtt_client_config_t mqtt_cfg = { .uri = "mqtts://mqtt.eclipse.org:8883", .event_handle = mqtt_event_handler, .cert_pem = (const char *)mqtt_eclipse_org_pem_start, }; If the certificate is not null-terminated then ``cert_len`` should also be set. Other SSL related configuration parameters are: * ``use_global_ca_store``: use the global certificate store to verify server certificate, see ``esp-tls.h`` for more information * ``client_cert_pem``: pointer to certificate data in PEM or DER format for SSL mutual authentication, default is NULL, not required if mutual authentication is not needed. * ``client_cert_len``: length of the buffer pointed to by client_cert_pem. May be 0 for null-terminated pem. * ``client_key_pem``: pointer to private key data in PEM or DER format for SSL mutual authentication, default is NULL, not required if mutual authentication is not needed. * ``client_key_len``: length of the buffer pointed to by client_key_pem. May be 0 for null-terminated pem. * ``psk_hint_key``: pointer to PSK struct defined in esp_tls.h to enable PSK authentication (as alternative to certificate verification). If not NULL and server/client certificates are NULL, PSK is enabled * ``alpn_protos``: NULL-terminated list of protocols to be used for ALPN. Last Will and Testament ^^^^^^^^^^^^^^^^^^^^^^^ MQTT allows for a last will and testament (LWT) message to notify other clients when a client ungracefully disconnects. This is configured by the following fields in the ``esp_mqtt_client_config_t``-struct. * ``lwt_topic``: pointer to the LWT message topic * ``lwt_msg``: pointer to the LWT message * ``lwt_msg_len``: length of the LWT message, required if ``lwt_msg`` is not null-terminated * ``lwt_qos``: quality of service for the LWT message * ``lwt_retain``: specifies the retain flag of the LWT message Other Configuration Parameters ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ * ``disable_clean_session``: determines the clean session flag for the connect message, defaults to a clean session * ``keepalive``: determines how many seconds the client will wait for a ping response before disconnecting, default is 120 seconds. * ``disable_auto_reconnect``: enable to stop the client from reconnecting to server after errors or disconnects * ``user_context``: custom context that will be passed to the event handler * ``task_prio``: MQTT task priority, defaults to 5 * ``task_stack``: MQTT task stack size, defaults to 6144 bytes, setting this will override setting from menuconfig * ``buffer_size``: size of MQTT send/receive buffer, default is 1024 bytes * ``username``: pointer to the username used for connecting to the broker * ``password``: pointer to the password used for connecting to the broker * ``client_id``: pointer to the client id, defaults to ``ESP32_%CHIPID%`` where %CHIPID% are the last 3 bytes of MAC address in hex format * ``host``: MQTT broker domain (ipv4 as string), setting the uri will override this * ``port``: MQTT broker port, specifying the port in the uri will override this * ``transport``: sets the transport protocol, setting the uri will override this * ``refresh_connection_after_ms``: refresh connection after this value (in milliseconds) * ``event_handle``: handle for MQTT events as a callback in legacy mode * ``event_loop_handle``: handle for MQTT event loop library For more options on ``esp_mqtt_client_config_t``, please refer to API reference below Change settings in Project Configuration Menu ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The settings for MQTT can be found using ``idf.py menuconfig``, under Component config -> ESP-MQTT Configuration The following settings are available: - :ref:`CONFIG_MQTT_PROTOCOL_311`: Enables 3.1.1 version of MQTT protocol - :ref:`CONFIG_MQTT_TRANSPORT_SSL`, :ref:`CONFIG_MQTT_TRANSPORT_WEBSOCKET`: Enables specific MQTT transport layer, such as SSL, WEBSOCKET, WEBSOCKET_SECURE - :ref:`CONFIG_MQTT_CUSTOM_OUTBOX`: Disables default implementation of mqtt_outbox, so a specific implementaion can be supplied Events ------ The following events may be posted by the MQTT client: * ``MQTT_EVENT_BEFORE_CONNECT``: The client is initialized and about to start connecting to the broker. * ``MQTT_EVENT_CONNECTED``: The client has successfully established a connection to the broker. The client is now ready to send and receive data. * ``MQTT_EVENT_DISCONNECTED``: The client has aborted the connection due to being unable to read or write data, e.g. because the server is unavailable. * ``MQTT_EVENT_SUBSCRIBED``: The broker has acknowledged the client's subscribe request. The event data will contain the message ID of the subscribe message. * ``MQTT_EVENT_UNSUBSCRIBED``: The broker has acknowledged the client's unsubscribe request. The event data will contain the message ID of the unsubscribe message. * ``MQTT_EVENT_PUBLISHED``: The broker has acknowledged the client's publish message. This will only be posted for Quality of Service level 1 and 2, as level 0 does not use acknowledgements. The event data will contain the message ID of the publish message. * ``MQTT_EVENT_DATA``: The client has received a publish message. The event data contains: message ID, name of the topic it was published to, received data and its length. For data that exceeds the internal buffer multiple `MQTT_EVENT_DATA` will be posted and `current_data_offset` and `total_data_len` from event data updated to keep track of the fragmented message. * ``MQTT_EVENT_ERROR``: The client has encountered an error. `esp_mqtt_error_type_t` from `error_handle` in the event data can be used to further determine the type of the error. The type of error will determine which parts of the `error_handle` struct is filled. API Reference ------------- .. include-build-file:: inc/mqtt_client.inc