Add MQTT support.

README.md

@@ -1,6 +1,6 @@
 # midi-request-trigger
 
-A service that triggers HTTP requests when MIDI messages are recieved and triggers MIDI messages when HTTP requests are received.
+A service that triggers HTTP requests and/or MQTT messages when MIDI messages are recieved and triggers MIDI messages when HTTP requests and/or MQTT messages are received.
 
 ## Install
 

go.mod

@@ -3,6 +3,7 @@ module github.com/GRMrGecko/midi-request-trigger
 go 1.20
 
 require (
+	github.com/eclipse/paho.mqtt.golang v1.5.0
 	github.com/gorilla/handlers v1.5.1
 	github.com/gorilla/mux v1.8.0
 	github.com/kkyr/fig v0.3.2
@@ -11,7 +12,10 @@ require (
 
 require (
 	github.com/felixge/httpsnoop v1.0.1 // indirect
+	github.com/gorilla/websocket v1.5.3 // indirect
 	github.com/mitchellh/mapstructure v1.4.1 // indirect
 	github.com/pelletier/go-toml v1.9.3 // indirect
+	golang.org/x/net v0.27.0 // indirect
+	golang.org/x/sync v0.7.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,9 +1,13 @@
+github.com/eclipse/paho.mqtt.golang v1.5.0 h1:EH+bUVJNgttidWFkLLVKaQPGmkTUfQQqjOsyvMGvD6o=
+github.com/eclipse/paho.mqtt.golang v1.5.0/go.mod h1:du/2qNQVqJf/Sqs4MEL77kR8QTqANF7XU7Fk0aOTAgk=
 github.com/felixge/httpsnoop v1.0.1 h1:lvB5Jl89CsZtGIWuTcDM1E/vkVs49/Ml7JJe07l8SPQ=
 github.com/felixge/httpsnoop v1.0.1/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/gorilla/handlers v1.5.1 h1:9lRY6j8DEeeBT10CvO9hGW0gmky0BprnvDI5vfhUHH4=
 github.com/gorilla/handlers v1.5.1/go.mod h1:t8XrUpc4KVXb7HGyJ4/cEnwQiaxrX/hz1Zv/4g96P1Q=
 github.com/gorilla/mux v1.8.0 h1:i40aqfkR1h2SlN9hojwV5ZA91wcXFOvkdNIeFDP5koI=
 github.com/gorilla/mux v1.8.0/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=
+github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
+github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/kkyr/fig v0.3.2 h1:+vMj52FL6RJUxeKOBB6JXIMyyi1/2j1ERDrZXjoBjzM=
 github.com/kkyr/fig v0.3.2/go.mod h1:ItUILF8IIzgZOMhx5xpJ1W/bviQsWRKOwKXfE/tqUoA=
 github.com/mitchellh/mapstructure v1.4.1 h1:CpVNEelQCZBooIPDn+AR3NpivK/TIKU8bDxdASFVQag=
@@ -12,6 +16,10 @@ github.com/pelletier/go-toml v1.9.3 h1:zeC5b1GviRUyKYd6OJPvBU/mcVDVoL1OhT17FCt5d
 github.com/pelletier/go-toml v1.9.3/go.mod h1:u1nR/EPcESfeI/szUZKdtJ0xRNbUoANCkoOuaOx1Y+c=
 gitlab.com/gomidi/midi/v2 v2.0.30 h1:RgRYbQeQSab5ZaP1lqRcCTnTSBQroE3CE6V9HgMmOAc=
 gitlab.com/gomidi/midi/v2 v2.0.30/go.mod h1:Y6IFFyABN415AYsFMPJb0/43TRIuVYDpGKp2gDYLTLI=
+golang.org/x/net v0.27.0 h1:5K3Njcw06/l2y9vpGCSdcxWOYHOUk3dVNGDXN+FvAys=
+golang.org/x/net v0.27.0/go.mod h1:dDi0PyhWNoiUOrAS8uXv/vnScO4wnHQO4mj9fn/RytE=
+golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
+golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

main.go

@@ -14,8 +14,8 @@ import (
 
 const (
 	serviceName        = "midi-request-trigger"
-	serviceDescription = "Takes trigger MIDI messages by HTTP requests and trigger HTTP requests by MIDI messages"
+	serviceDescription = "Takes trigger MIDI messages by HTTP or MQTT requests and trigger HTTP or MQTT requests by MIDI messages"
-	serviceVersion     = "0.1"
+	serviceVersion     = "0.2"
 )
 
 // App is the global application structure for communicating between servers and storing information.

midiRouter.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"crypto/tls"
+	"encoding/json"
 	"fmt"
 	"io"
 	"log"
@@ -11,50 +12,166 @@ import (
 	"strconv"
 	"strings"
 
+	mqtt "github.com/eclipse/paho.mqtt.golang"
 	"gitlab.com/gomidi/midi/v2"
 	"gitlab.com/gomidi/midi/v2/drivers"
 )
 
-// Triggers that occur from MIDI messages received.
+// LogLevel Definition
-type NoteTrigger struct {
+type LogLevel int
-	MatchAllNotes      bool        `fig:"match_all_notes"`
+
-	Channel            uint8       `fig:"channel"`
+const (
-	Note               uint8       `fig:"note"`
+	// Logs only errors.
-	Velocity           uint8       `fig:"velocity"`
+	ErrorLog LogLevel = iota
-	MatchAllVelocities bool        `fig:"match_all_velocities"`
+	// MQTT, HTTP, and MIDI receive logging.
-	MidiInfoInRequest  bool        `fig:"midi_info_in_request"`
+	ReceiveLog
-	InsecureSkipVerify bool        `fig:"insecure_skip_verify"`
+	// MQTT, HTTP, and MIDI send logging.
-	URL                string      `fig:"url"`
+	SendLog
-	Method             string      `fig:"method"`
+	// Debug messages.
-	Body               string      `fig:"body"`
+	DebugLog
-	Headers            http.Header `fig:"headers"`
+)
-	DebugRequest       bool        `fig:"debug_request"`
+
+// Provides a string value for a log level.
+func (l LogLevel) String() string {
+	return [...]string{"Error", "Receive", "Send", "Debug"}[l]
 }
 
-// Triggers that occur from HTTP messsages received.
+// Configurations relating to MQTT connection.
+type MQTTConfig struct {
+	// Hostname of the MQTT broker.
+	Host string `fig:"host"`
+	// Port of the MQTT broker.
+	Port int `fig:"port"`
+	// MQTT client ID of this relay.
+	ClientId string `fig:"client_id"`
+	// User name used for MQTT authentication.
+	User string `fig:"user"`
+	// Password used for MQTT authentication.
+	Password string `fig:"password"`
+	// Topic where MQTT messages are pushed and received.
+	// Set topic to `midi/example` and the following topics will be setup.
+	// midi/example/cmd - Any commands received on MIDI will publish here.
+	// midi/example/send - Any commands pushed via MQTT will be forwarded to MIDI.
+	// midi/example/status - Configuration is published on startup.
+	// midi/example/status/check - Request status.
+	Topic string `fig:"topic"`
+	// Disable sending all midi notes.
+	DisableMidiFirehose bool `fig:"disable_midi_firehose"`
+	// Disables the config send.
+	DisableConfigSend bool `fig:"disable_config_send"`
+}
+
+// Payload to decode/encode JSON message.
+type MQTTPayload struct {
+	Channel  uint8 `json:"channel"`
+	Note     uint8 `json:"note"`
+	Velocity uint8 `json:"velocity"`
+}
+
+// Triggers that occur from MIDI messages received.
+type NoteTrigger struct {
+	// If set, every note played will be matched.
+	MatchAllNotes bool `fig:"match_all_notes"`
+	// Channel to match.
+	Channel uint8 `fig:"channel"`
+	// Note to match.
+	Note uint8 `fig:"note"`
+	// Velocity to match.
+	Velocity uint8 `fig:"velocity"`
+	// If we should match all velocity values.
+	MatchAllVelocities bool `fig:"match_all_velocities"`
+	// Custom MQTT message. Do not set to ignore MQTT.
+	MqttTopic string `fig:"mqtt_topic"`
+	// Nil payload will generate a payload with midi info.
+	MqttPayload []interface{} `fig:"mqtt_payload"`
+	// If the HTTP request should includ midi info.
+	MidiInfoInRequest bool `fig:"midi_info_in_request"`
+	// Should SSL requests require a valid certificate.
+	InsecureSkipVerify bool `fig:"insecure_skip_verify"`
+	// The URL to call with the HTTP request. Do not set if you wish to not send HTTP request.
+	URL string `fig:"url"`
+	// HTTP method, defaults to GET.
+	Method string `fig:"method"`
+	// HTTP body.
+	Body string `fig:"body"`
+	// HTTP headers.
+	Headers http.Header `fig:"headers"`
+}
+
+// Triggers that occur from HTTP or MQTT messsages received.
 type RequestTrigger struct {
-	Channel           uint8  `fig:"channel"`
+	Channel  uint8 `fig:"channel"`
-	Note              uint8  `fig:"note"`
+	Note     uint8 `fig:"note"`
-	Velocity          uint8  `fig:"velocity"`
+	Velocity uint8 `fig:"velocity"`
-	MidiInfoInRequest bool   `fig:"midi_info_in_request"`
+	// Parse midi notes from HTTP request.
-	URI               string `fig:"uri"`
+	MidiInfoInRequest bool `fig:"midi_info_in_request"`
+	// Absolute MQTT topic to subscribe.
+	MqttTopic string `fig:"mqtt_topic"`
+	// Sub topic off relay MQTT topic to subscribe.
+	// midi/example/$SUB_TOPIC
+	MqttSubTopic string `fig:"mqtt_sub_topic"`
+	// Rather or not to disallow payload to be relayed.
+	DisallowPayload bool `fig:"disallow_payload"`
+	// Request URL path to trigger with.
+	URI string `fig:"uri"`
 }
 
 // A common router for both receiving and sending MIDI messages.
 type MidiRouter struct {
-	Name            string           `fig:"name"`
+	// Used for human readable config.
-	Device          string           `fig:"device"`
+	Name string `fig:"name"`
-	DebugListener   bool             `fig:"debug_listener"`
+	// Midi device to connect.
-	DisableListener bool             `fig:"disable_listener"`
+	Device string `fig:"device"`
-	NoteTriggers    []NoteTrigger    `fig:"note_triggers"`
+	// MQTT Connection if you are to integrate with MQTT.
+	MQTT MQTTConfig `fig:"mqtt"`
+	// Only connect for sending notes, not receiving.
+	DisableListener bool `fig:"disable_listener"`
+	// Listener triggers for notes to send HTTP and or MQTT messages.
+	NoteTriggers []NoteTrigger `fig:"note_triggers"`
+	// HTTP and or MQTT triggers to send MIDI notes.
 	RequestTriggers []RequestTrigger `fig:"request_triggers"`
 
-	MidiOut      drivers.Out `fig:"-"`
+	// How much logging.
-	ListenerStop func()      `fig:"-"`
+	// 0 - Errors
+	// 1 - MQTT and OSC receive logging.
+	// 2 - MQTT and OSC send logging.
+	// 3 - Debug
+	LogLevel LogLevel `yaml:"log_level" json:"log_level"`
+
+	// Connection to MIDI device.
+	MidiOut drivers.Out `fig:"-"`
+	// Function to stop listening to MIDI device.
+	ListenerStop func() `fig:"-"`
+	// The client connection to MQTT.
+	MqttClient mqtt.Client `yaml:"-" json:"-"`
+}
+
+// Logging function to allow log levels.
+func (r *MidiRouter) Log(level LogLevel, format string, args ...interface{}) {
+	if level <= r.LogLevel {
+		log.Println(fmt.Sprintf(format, args...))
+	}
 }
 
 // When a MIDI message occurs, send the HTTP request.
 func (r *MidiRouter) sendRequest(channel, note, velocity uint8) {
+	// If MQTT firehose not disabled, send to general cmd topic.
+	if r.MQTT.Host != "" && r.MQTT.Port != 0 && !r.MQTT.DisableMidiFirehose {
+		payload := MQTTPayload{
+			Channel:  channel,
+			Note:     note,
+			Velocity: velocity,
+		}
+		data, err := json.Marshal(payload)
+		if err != nil {
+			r.Log(ErrorLog, "Json Encode: %s", err)
+		} else {
+			topic := r.MQTT.Topic + "/cmd"
+			r.MqttClient.Publish(topic, 0, true, data)
+			r.Log(SendLog, "-> [MQTT] %s", topic)
+		}
+	}
+
 	// Check each trigger to find requests that match this message.
 	for _, trig := range r.NoteTriggers {
 		// If match all notes, process this request.
@@ -64,73 +181,93 @@ func (r *MidiRouter) sendRequest(channel, note, velocity uint8) {
 			// For all logging, we want to print the message so setup a common string to print.
 			logInfo := fmt.Sprintf("note %s(%d) on channel %v with velocity %v", midi.Note(note), note, channel, velocity)
 
-			// Default method to GET if nothing is defined.
+			if trig.MqttTopic != "" {
-			if trig.Method == "" {
+				if trig.MqttPayload != nil {
-				trig.Method = "GET"
+					r.MqttClient.Publish(trig.MqttTopic, 0, true, trig.MqttPayload)
+					r.Log(SendLog, "-> [MQTT] %s", trig.MqttTopic)
+				} else {
+					payload := MQTTPayload{
+						Channel:  channel,
+						Note:     note,
+						Velocity: velocity,
+					}
+					data, err := json.Marshal(payload)
+					if err != nil {
+						r.Log(ErrorLog, "Json Encode: %s", err)
+					} else {
+						r.MqttClient.Publish(trig.MqttTopic, 0, true, data)
+						r.Log(SendLog, "-> [MQTT] %s", trig.MqttTopic)
+					}
+				}
 			}
 
-			// Parse the URL to make sure its valid.
+			if trig.URL != "" {
-			url, err := url.Parse(trig.URL)
+				// Default method to GET if nothing is defined.
-			// If not valid, we need to stop processing this request.
+				if trig.Method == "" {
-			if err != nil {
+					trig.Method = "GET"
-				log.Printf("Trigger failed to parse url: %s\n %s\n", err, logInfo)
+				}
-				continue
-			}
 
-			// If MIDI info needs to be added to the request, add it.
+				// Parse the URL to make sure its valid.
-			if trig.MidiInfoInRequest {
+				url, err := url.Parse(trig.URL)
-				query := url.Query()
+				// If not valid, we need to stop processing this request.
-				query.Add("channel", strconv.Itoa(int(channel)))
-				query.Add("note", strconv.Itoa(int(note)))
-				query.Add("velocity", strconv.Itoa(int(velocity)))
-				url.RawQuery = query.Encode()
-			}
-
-			// If body provided, setup a reader for it.
-			var body io.Reader
-			if trig.Body != "" {
-				body = strings.NewReader(trig.Body)
-			}
-
-			// If debugging, log that we're starting a request.
-			if trig.DebugRequest {
-				log.Printf("Starting request for trigger: %s %s\n%s\n", trig.Method, url.String(), logInfo)
-			}
-
-			// Make the request.
-			req, err := http.NewRequest(trig.Method, url.String(), body)
-			if err != nil {
-				log.Printf("Trigger failed to parse url: %s\n %s\n", err, logInfo)
-				continue
-			}
-
-			// Add headers to the request.
-			req.Header = trig.Headers
-
-			// Configure transport with trigger config.
-			tr := &http.Transport{
-				TLSClientConfig: &tls.Config{InsecureSkipVerify: trig.InsecureSkipVerify},
-			}
-			client := &http.Client{Transport: tr}
-
-			// Perform the request.
-			res, err := client.Do(req)
-			if err != nil {
-				log.Printf("Trigger failed to request: %s\n %s\n", err, logInfo)
-				continue
-			}
-
-			// Close the body at end of request.
-			defer res.Body.Close()
-
-			// If debug enabled, read the body and log it.
-			if trig.DebugRequest {
-				body, err := io.ReadAll(res.Body)
 				if err != nil {
-					log.Printf("Trigger failed to read body: %s\n %s\n", err, logInfo)
+					r.Log(ErrorLog, "Trigger failed to parse url: %s\n %s", err, logInfo)
 					continue
 				}
-				log.Printf("Trigger response: %s\n%s\n", logInfo, string(body))
+
+				// If MIDI info needs to be added to the request, add it.
+				if trig.MidiInfoInRequest {
+					query := url.Query()
+					query.Add("channel", strconv.Itoa(int(channel)))
+					query.Add("note", strconv.Itoa(int(note)))
+					query.Add("velocity", strconv.Itoa(int(velocity)))
+					url.RawQuery = query.Encode()
+				}
+
+				// If body provided, setup a reader for it.
+				var body io.Reader
+				if trig.Body != "" {
+					body = strings.NewReader(trig.Body)
+				}
+
+				// If debugging, log that we're starting a request.
+				r.Log(DebugLog, "Starting request for trigger: %s %s\n%s", trig.Method, url.String(), logInfo)
+
+				// Make the request.
+				req, err := http.NewRequest(trig.Method, url.String(), body)
+				if err != nil {
+					r.Log(ErrorLog, "Trigger failed to parse url: %s\n %s", err, logInfo)
+					continue
+				}
+
+				// Add headers to the request.
+				req.Header = trig.Headers
+
+				// Configure transport with trigger config.
+				tr := &http.Transport{
+					TLSClientConfig: &tls.Config{InsecureSkipVerify: trig.InsecureSkipVerify},
+				}
+				client := &http.Client{Transport: tr}
+
+				// Perform the request.
+				res, err := client.Do(req)
+				if err != nil {
+					r.Log(ErrorLog, "Trigger failed to request: %s\n %s", err, logInfo)
+					continue
+				}
+
+				// Close the body at end of request.
+				defer res.Body.Close()
+
+				// If debug enabled, read the body and log it.
+				if r.LogLevel >= DebugLog {
+					body, err := io.ReadAll(res.Body)
+					if err != nil {
+						r.Log(ErrorLog, "Trigger failed to read body: %s\n %s", err, logInfo)
+						continue
+					}
+					r.Log(DebugLog, "Trigger response: %s\n%s", logInfo, string(body))
+				}
 			}
 		}
 	}
@@ -141,7 +278,7 @@ func (m *MidiRouter) Handler(w http.ResponseWriter, r *http.Request) {
 	// Check each request trigger for ones that match the request URI.
 	for _, t := range m.RequestTriggers {
 		// If matches request, process MIDI message.
-		if t.URI == r.URL.RawPath {
+		if t.URI != "" && t.URI == r.URL.RawPath {
 			// Set default values to those from this trigger.
 			channel, note, velocity := t.Channel, t.Note, t.Velocity
 			// If MIDI info is in the request query, update to request.
@@ -179,7 +316,7 @@ func (m *MidiRouter) Handler(w http.ResponseWriter, r *http.Request) {
 			// Get send function for output.
 			send, err := midi.SendTo(m.MidiOut)
 			if err != nil {
-				log.Printf("Failed to get midi sender for request: %s\n%s\n", t.URI, err)
+				m.Log(ErrorLog, "Failed to get midi sender for request: %s\n%s", t.URI, err)
 				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 				return
 			}
@@ -193,7 +330,7 @@ func (m *MidiRouter) Handler(w http.ResponseWriter, r *http.Request) {
 			// Send MIDI message.
 			err = send(msg)
 			if err != nil {
-				log.Printf("Failed to send midi message: %s\n%s\n", t.URI, err)
+				m.Log(ErrorLog, "Failed to send midi message: %s\n%s", t.URI, err)
 				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 				return
 			}
@@ -204,6 +341,116 @@ func (m *MidiRouter) Handler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// Send config to MQTT status.
+func (r *MidiRouter) SendStatus() {
+	// If disabled, ignore.
+	if r.MQTT.DisableConfigSend {
+		return
+	}
+
+	// Make JSON dump.
+	config, err := json.Marshal(&r)
+	if err != nil {
+		r.Log(ErrorLog, "Json Error: %s", err)
+	}
+
+	// Send config.
+	r.MqttClient.Publish(r.MQTT.Topic+"/status", 0, true, config)
+}
+
+// Handle MQTT events.
+func (r *MidiRouter) MqttOnEvent(client mqtt.Client, message mqtt.Message) {
+	r.Log(ReceiveLog, "<- [MQTT] %s: %s\n", message.Topic(), message.Payload())
+
+	// Check commands to see if one matches this topic.
+	for _, t := range r.RequestTriggers {
+		if (t.MqttTopic != "" && message.Topic() == t.MqttTopic) ||
+			(t.MqttSubTopic != "" && message.Topic() == r.MQTT.Topic+"/"+t.MqttSubTopic) {
+			// Set default values to those from this trigger.
+			channel, note, velocity := t.Channel, t.Note, t.Velocity
+
+			// If arguments allowed and provided, parse, otherwise use default payload.
+			arguments := MQTTPayload{
+				Channel:  channel,
+				Note:     note,
+				Velocity: velocity,
+			}
+			if !t.DisallowPayload && len(message.Payload()) != 0 {
+				err := json.Unmarshal(message.Payload(), &arguments)
+				if err != nil {
+					r.Log(ErrorLog, "Json Error: %s", err)
+					return
+				}
+				channel = arguments.Channel
+				note = arguments.Note
+				velocity = arguments.Velocity
+			}
+
+			// Get send function for output.
+			send, err := midi.SendTo(r.MidiOut)
+			if err != nil {
+				log.Printf("Failed to get midi sender for request: %s\n%s\n", message.Topic(), err)
+				return
+			}
+
+			// Make the MIDI message based on information.
+			msg := midi.NoteOn(channel, note, velocity)
+			if velocity == 0 {
+				msg = midi.NoteOff(channel, note)
+			}
+
+			// Send MIDI message.
+			err = send(msg)
+			if err != nil {
+				log.Printf("Failed to send midi message: %s\n%s\n", message.Topic(), err)
+				return
+			}
+		}
+	}
+
+	// If standard send topic.
+	if strings.HasPrefix(message.Topic(), r.MQTT.Topic+"/send") {
+		// If arguments allowed and provided, parse, otherwise use default payload.
+		var arguments MQTTPayload
+		if len(message.Payload()) != 0 {
+			err := json.Unmarshal(message.Payload(), &arguments)
+			if err != nil {
+				r.Log(ErrorLog, "Json Error: %s", err)
+				return
+			}
+			// Get send function for output.
+			send, err := midi.SendTo(r.MidiOut)
+			if err != nil {
+				log.Printf("Failed to get midi sender for request: %s\n%s\n", message.Topic(), err)
+				return
+			}
+
+			// Make the MIDI message based on information.
+			msg := midi.NoteOn(arguments.Channel, arguments.Note, arguments.Velocity)
+			if arguments.Velocity == 0 {
+				msg = midi.NoteOff(arguments.Channel, arguments.Note)
+			}
+
+			// Send MIDI message.
+			err = send(msg)
+			if err != nil {
+				log.Printf("Failed to send midi message: %s\n%s\n", message.Topic(), err)
+				return
+			}
+		}
+	} else if message.Topic() == r.MQTT.Topic+"/status/check" {
+		r.SendStatus()
+	}
+}
+
+// Subscribe to MQTT Topic.
+func (r *MidiRouter) MqttSubscribe(topic string) {
+	r.Log(DebugLog, "Subscribing MQTT: %s", topic)
+	if t := r.MqttClient.Subscribe(topic, 0, r.MqttOnEvent); t.Wait() && t.Error() != nil {
+		r.Log(ErrorLog, "MQTT Subscribe Error: %s", t.Error())
+	}
+}
+
 // Connect to MIDI devices and start listening.
 func (r *MidiRouter) Connect() {
 	// If request triggers defined, find the out port.
@@ -234,19 +481,13 @@ func (r *MidiRouter) Connect() {
 		switch {
 		// Get notes with an velocity set.
 		case msg.GetNoteStart(&channel, &note, &velocity):
-			// If debug, log.
+			r.Log(ReceiveLog, "starting note %s(%d) on channel %v with velocity %v", midi.Note(note), note, channel, velocity)
-			if r.DebugListener {
-				log.Printf("starting note %s(%d) on channel %v with velocity %v\n", midi.Note(note), note, channel, velocity)
-			}
 			// Process request.
 			r.sendRequest(channel, note, velocity)
 
 		// If no velocity is set, an note end message is received.
 		case msg.GetNoteEnd(&channel, &note):
-			// If debug, log.
+			r.Log(ReceiveLog, "ending note %s(%d) on channel %v", midi.Note(note), note, channel)
-			if r.DebugListener {
-				log.Printf("ending note %s(%d) on channel %v\n", midi.Note(note), note, channel)
-			}
 			// Process request.
 			r.sendRequest(channel, note, 0)
 		default:
@@ -254,12 +495,42 @@ func (r *MidiRouter) Connect() {
 		}
 	})
 	if err != nil {
-		log.Printf("Error listening to device: %s\n", err)
+		r.Log(ErrorLog, "Error listening to device: %s", err)
 		return
 	}
 
 	// Update stop function for disconnects.
 	r.ListenerStop = stop
+
+	if r.MQTT.Host != "" && r.MQTT.Port != 0 {
+		// Connect to MQTT.
+		mqtt_opts := mqtt.NewClientOptions()
+		mqtt_opts.AddBroker(fmt.Sprintf("tcp://%s:%d", r.MQTT.Host, r.MQTT.Port))
+		mqtt_opts.SetClientID(r.MQTT.ClientId)
+		mqtt_opts.SetUsername(r.MQTT.User)
+		mqtt_opts.SetPassword(r.MQTT.Password)
+		r.MqttClient = mqtt.NewClient(mqtt_opts)
+
+		// Connect and failures are fatal exiting service.
+		r.Log(DebugLog, "Connecting to MQTT")
+		if t := r.MqttClient.Connect(); t.Wait() && t.Error() != nil {
+			log.Fatalf("MQTT error: %s", t.Error())
+			return
+		}
+
+		// Subscribe to MQTT topics.
+		r.MqttSubscribe(r.MQTT.Topic + "/send")
+		r.MqttSubscribe(r.MQTT.Topic + "/status/check")
+		// Subscribe to command topics configured.
+		for _, trig := range r.RequestTriggers {
+			if trig.MqttTopic != "" {
+				r.MqttSubscribe(trig.MqttTopic)
+			}
+			if trig.MqttSubTopic != "" {
+				r.MqttSubscribe(r.MQTT.Topic + "/" + trig.MqttSubTopic)
+			}
+		}
+	}
 }
 
 // On disconnect, stop and remove output device.