(net mq mqtt) - MQTT library

Providing MQTT v3.1.1 and partially v3.1 client APIs.

Reference OASIS MQTT.

Following examples describe how to receive and publish messages.

(import (rnrs) (net mq mqtt))

(let ((conn (open-mqtt-connection "localhost" "1883")))
  ;; subscribes to "topic" topic with accepting QoS exactly once
  (mqtt-subscribe conn "topic" +qos-exactly-once+
                  (lambda (topic payload)
                    (let ((msg (get-bytevector-all payload)))
                      (cond ((not (eof-object? msg))
                             (print (utf8->string msg))
                             (string=? (utf8->string msg) "END"))
                            (else #f)))))
  (let loop ()
    ;; receives until "END" message was sent
    (unless (mqtt-receive-message conn)
      (loop)))
  ;; unsubscribe from "topic"
  (mqtt-unsubscribe conn "topic")
  (close-mqtt-connection! conn))

(import (rnrs) (net mq mqtt))

(let ((conn (open-mqtt-connection "localhost" "1883")))
  ;; publish message to "topic" topic.
  (mqtt-publish conn "topic" (string->utf8 "Hello MQTT"))
  (close-mqtt-connection! conn))

Returns #t if given obj is MQTT connection. Otherwise #f.

Creates a socket connected to host:port and pass it to port->mqtt-connection with opts.

The returning value is an MQTT connection object.

in/out must be a binary input/outport port.

Creates an MQTT connection object using in/out.

client-id, username, password and _keep-alive_keyword arguments are for optional payload of CONNECT packet. If they are given, then first 3 must be strings and keep-alive must be an integer.

version keyword argument is switches which version it should use. The value must be one of the followings;

By default it uses +mqtt-3.1.1+.

This procedure is for future extension such as supporting websocket.

Closes given MQTT connection.

Subscribes to given topic with QoS qos.

callback must be a procedure and accept 2 arguments. topic and payload. payload is an binary input port.

To receive messages, use mqtt-receive-message.

Receives one message from one of subscribed topics and call registered callback.

Unsubscribes conn from topic.

Publishes application message message to topic.

The topic must be a string. The message must be a bytevector.

If keyword argument qos is specified, it must be one of the followings.

By default, it uses +qos-at-most-once+.

Sends PINGREQ packet to the server.

(import (rnrs) (net mq mqtt broker))

;; Wait on port 9000
(define broker (make-mqtt-broker "9000")))

;; start the broker.
(mqtt-broker-start! broker)