ESP32_ChinaDieselHeater_Control/lib/async-mqtt-client/docs/2.-API-reference.md

API reference

AsyncMqttClient()

Instantiate a new AsyncMqttClient object.

Configuration

AsyncMqttClient& setKeepAlive(uint16_t keepAlive)

Set the keep alive. Defaults to 15 seconds.

• keepAlive: Keep alive in seconds

AsyncMqttClient& setClientId(const char* clientId)

Set the client ID. Defaults to esp8266<chip ID on 6 hex caracters>.

• clientId: Client ID

AsyncMqttClient& setCleanSession(bool cleanSession)

Whether or not to set the CleanSession flag. Defaults to true.

• cleanSession: clean session wanted or not

AsyncMqttClient& setMaxTopicLength(uint16_t maxTopicLength)

Set the maximum allowed topic length to receive. If an MQTT packet is received with a topic longer than this maximum, the packet will be ignored. Defaults to 128.

• maxTopicLength: Maximum allowed topic length to receive

AsyncMqttClient& setCredentials(const char* username, const char* password = nullptr)

Set the username/password. Defaults to non-auth.

• username: Username
• password: Password

AsyncMqttClient& setWill(const char* topic, uint8_t qos, bool retain, const char* payload = nullptr, size_t length = 0)

Set the Last Will Testament. Defaults to none.

• topic: Topic of the LWT
• qos: QoS of the LWT
• retain: Retain flag of the LWT
• payload: Payload of the LWT. If unset, the payload will be empty
• length: Payload length. If unset or set to 0, the payload will be considered as a string and its size will be calculated using strlen(payload)

AsyncMqttClient& setServer(IPAddress ip, uint16_t port)

Set the server.

• ip: IP of the server
• port: Port of the server

AsyncMqttClient& setServer(const char* host, uint16_t port)

Set the server.

• host: Host of the server
• port: Port of the server

AsyncMqttClient& setSecure(bool secure)

Whether or not to use SSL. Defaults to false.

• secure: SSL wanted or not.

AsyncMqttClient& addServerFingerprint(const uint8_t* fingerprint)

Adds an acceptable server fingerprint (SHA1). This may be called multiple times to permit any one of the specified fingerprints. By default, if no fingerprint is added, any fingerprint is accepted.

• fingerprint: Fingerprint to add

Events handlers

AsyncMqttClient& onConnect(AsyncMqttClientInternals::OnConnectUserCallback callback)

Add a connect event handler.

• callback: Function to call

AsyncMqttClient& onDisconnect(AsyncMqttClientInternals::OnDisconnectUserCallback callback)

Add a disconnect event handler.

• callback: Function to call

AsyncMqttClient& onSubscribe(AsyncMqttClientInternals::OnSubscribeUserCallback callback)

Add a subscribe acknowledged event handler.

• callback: Function to call

AsyncMqttClient& onUnsubscribe(AsyncMqttClientInternals::OnUnsubscribeUserCallback callback)

Add an unsubscribe acknowledged event handler.

• callback: Function to call

AsyncMqttClient& onMessage(AsyncMqttClientInternals::OnMessageUserCallback callback)

Add a publish received event handler.

• callback: Function to call

AsyncMqttClient& onPublish(AsyncMqttClientInternals::OnPublishUserCallback callback)

Add a publish acknowledged event handler.

• callback: Function to call

Operation functions

bool connected()

Return if the client is currently connected to the broker or not.

void connect()

Connect to the server.

void disconnect(bool force = false)

Disconnect from the server.

• force: Whether to force the disconnection. Defaults to false (clean disconnection).

uint16_t subscribe(const char* topic, uint8_t qos)

Subscribe to the given topic at the given QoS.

Return the packet ID or 0 if failed.

• topic: Topic
• qos: QoS

uint16_t unsubscribe(const char* topic)

Unsubscribe from the given topic.

Return the packet ID or 0 if failed.

• topic: Topic

uint16_t publish(const char* topic, uint8_t qos, bool retain, const char* payload = nullptr, size_t length = 0, bool dup = false, uint16_t message_id = 0)

Publish a packet.

Return the packet ID (or 1 if QoS 0) or 0 if failed.

• topic: Topic
• qos: QoS
• retain: Retain flag
• payload: Payload. If unset, the payload will be empty
• length: Payload length. If unset or set to 0, the payload will be considered as a string and its size will be calculated using strlen(payload)
• dup: Duplicate flag. If set or set to 1, the payload will be flagged as a duplicate
• message_id: The message ID. If unset or set to 0, the message ID will be automtaically assigned. Use this with the DUP flag to identify which message is being duplicated