exmqttc v0.6.0 Exmqttc

Exmqttc provides a connection to a MQTT server based on emqttc

Link to this section Summary

Types

A PID like type

A QoS level

A single topic, a list of topics or a list of tuples of topic and QoS level

Functions

Returns a specification to start this module under a supervisor

Disconnect socket from MQTT server

Invoked when the server is started. start_link/3 or start/3 will block until it returns

Publish a message to MQTT. opts is a keywordlist and supports :retain with a boolean and :qos with an integer from 1 to 3

Start the Exmqttc client. callback_module is used for callbacks and should implement the Exmqttc.Callback behaviour. opts are passed directly to GenServer. mqtt_opts are reformatted so all options can be passed in as a Keyworld list. Params are passed to your callbacks init function

Subscribe to the given topic(s) given as topics with a given qos

Publish a message to MQTT synchronously. opts is a keywordlist and supports :retain with a boolean and :qos with an integer from 1 to 3

Subscribe to the given topics while blocking until the subscribtion has been confirmed by the server

Unsubscribe from the given topic(s) given as topics

Link to this section Types

Link to this type pidlike()
pidlike() :: pid() | port() | atom() | {atom(), node()}

A PID like type

Link to this type qos()
qos() :: :qos0 | :qos1 | :qos2

A QoS level

Link to this type topics()
topics() :: String.t() | [String.t()] | [{String.t(), qos()}]

A single topic, a list of topics or a list of tuples of topic and QoS level

Link to this section Functions

Link to this function child_spec(arg)

Returns a specification to start this module under a supervisor.

See Supervisor.

Link to this function disconnect(pid)
disconnect(pid()) :: :ok

Disconnect socket from MQTT server

Invoked when the server is started. start_link/3 or start/3 will block until it returns.

args is the argument term (second argument) passed to start_link/3.

Returning {:ok, state} will cause start_link/3 to return {:ok, pid} and the process to enter its loop.

Returning {:ok, state, timeout} is similar to {:ok, state} except handle_info(:timeout, state) will be called after timeout milliseconds if no messages are received within the timeout.

Returning {:ok, state, :hibernate} is similar to {:ok, state} except the process is hibernated before entering the loop. See c:handle_call/3 for more information on hibernation.

Returning :ignore will cause start_link/3 to return :ignore and the process will exit normally without entering the loop or calling c:terminate/2. If used when part of a supervision tree the parent supervisor will not fail to start nor immediately try to restart the GenServer. The remainder of the supervision tree will be (re)started and so the GenServer should not be required by other processes. It can be started later with Supervisor.restart_child/2 as the child specification is saved in the parent supervisor. The main use cases for this are:

  • The GenServer is disabled by configuration but might be enabled later.
  • An error occurred and it will be handled by a different mechanism than the Supervisor. Likely this approach involves calling Supervisor.restart_child/2 after a delay to attempt a restart.

Returning {:stop, reason} will cause start_link/3 to return {:error, reason} and the process to exit with reason reason without entering the loop or calling c:terminate/2.

Callback implementation for GenServer.init/1.

Link to this function publish(pid, topic, payload, opts \\ [])
publish(pid(), binary(), binary(), list()) :: :ok

Publish a message to MQTT. opts is a keywordlist and supports :retain with a boolean and :qos with an integer from 1 to 3

Link to this function start_link(callback_module, opts \\ [], mqtt_opts \\ [], params \\ [])

Start the Exmqttc client. callback_module is used for callbacks and should implement the Exmqttc.Callback behaviour. opts are passed directly to GenServer. mqtt_opts are reformatted so all options can be passed in as a Keyworld list. Params are passed to your callbacks init function.

mqtt_opts supports the following options:

  • host: Connection host, charlist, default: 'localhost'
  • port: Connection port, integer, default 1883
  • client_id: Binary ID for client, automatically set to UUID if not specified
  • clean_sess: MQTT cleanSession flag. true disables persistent sessions on the server
  • keepalive: Keepalive timer, integer
  • username: Login username, binary
  • password: Login password, binary
  • will: Last will, keywordlist, sample: [qos: 1, retain: false, topic: "WillTopic", payload: "I died"]
  • connack_timeout: Timeout for connack package, integer, default 60
  • puback_timeout: Timeout for puback package, integer, default 8
  • suback_timeout: Timeout for suback package, integer, default 4
  • ssl: List of ssl options
  • auto_resub: Automatically resubscribe to topics, boolean, default: false
  • reconnect: Automatically reconnect on lost connection, integer (), default false
Link to this function subscribe(pid, topics, qos \\ :qos0)
subscribe(pidlike(), topics(), qos()) :: :ok

Subscribe to the given topic(s) given as topics with a given qos.

Link to this function sync_publish(pid, topic, payload, opts \\ [])
sync_publish(pid(), binary(), binary(), list()) :: :ok

Publish a message to MQTT synchronously. opts is a keywordlist and supports :retain with a boolean and :qos with an integer from 1 to 3

Link to this function sync_subscribe(pid, topics)
sync_subscribe(pid(), topics()) :: :ok

Subscribe to the given topics while blocking until the subscribtion has been confirmed by the server.

Link to this function unsubscribe(pid, topics)
unsubscribe(pidlike(), topics()) :: :ok

Unsubscribe from the given topic(s) given as topics.