{"id":2603,"date":"2024-06-22T09:35:47","date_gmt":"2024-06-22T07:35:47","guid":{"rendered":"https:\/\/www.domotic.phdata.fr\/domotic\/?p=2603"},"modified":"2024-06-23T16:19:49","modified_gmt":"2024-06-23T14:19:49","slug":"mqtt","status":"publish","type":"post","link":"https:\/\/www.domotic.phdata.fr\/domotic\/mqtt\/","title":{"rendered":"MQTT"},"content":{"rendered":"\t\t
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MQTT<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Communication MQTT (Message Queuing Telemetry Transport)<\/h3>

Le MQTT (Message Queuing Telemetry Transport) est un protocole de messagerie l\u00e9ger con\u00e7u pour les communications machine-\u00e0-machine (M2M) et l’Internet des objets (IoT). Il est particuli\u00e8rement utile dans des environnements o\u00f9 la bande passante est limit\u00e9e, la latence \u00e9lev\u00e9e ou la fiabilit\u00e9 critique. Voici un aper\u00e7u d\u00e9taill\u00e9 de la communication MQTT, ses composants, son fonctionnement et ses avantages.<\/p>

Composants Principaux<\/h3>
  1. Broker\u00a0<\/a>:
    • Le c\u0153ur du syst\u00e8me MQTT.<\/li>
    • Responsable de la r\u00e9ception de tous les messages publi\u00e9s par les clients et de leur acheminement vers les clients abonn\u00e9s aux sujets correspondants.<\/li>
    • Exemples de brokers : Mosquitto, HiveMQ, EMQX.<\/li><\/ul><\/li>
    • Clients<\/strong> :
      • Dispositifs ou applications qui publient des messages sur des sujets ou s’abonnent \u00e0 des sujets pour recevoir des messages.<\/li>
      • Exemples : ESP32, ESP8266, smartphones, ordinateurs, capteurs IoT.<\/li><\/ul><\/li><\/ol>

        Concepts Cl\u00e9s<\/h3>
        1. Topic (Sujet)<\/strong> :
          • Un chemin hi\u00e9rarchique utilis\u00e9 pour organiser et acc\u00e9der aux messages.<\/li>
          • Exemples de sujets : home\/temperature<\/code>, office\/lights\/status<\/code>.<\/li><\/ul><\/li>
          • Publish (Publier)<\/strong> :
            • Acte d’envoyer un message \u00e0 un topic sp\u00e9cifique.<\/li>
            • Exemple : Un capteur de temp\u00e9rature peut publier les donn\u00e9es de temp\u00e9rature sur le topic home\/temperature<\/code>.<\/li><\/ul><\/li>
            • Subscribe (S’abonner)<\/strong> :
              • Acte de s’abonner \u00e0 un topic pour recevoir les messages publi\u00e9s sur ce topic.<\/li>
              • Exemple : Un affichage peut s’abonner au topic home\/temperature<\/code> pour afficher les donn\u00e9es de temp\u00e9rature.<\/li><\/ul><\/li>
              • QoS (Quality of Service)<\/strong> :
                • Niveau de garantie de livraison des messages.<\/li>
                • QoS 0 : Au moins une fois (non confirm\u00e9).<\/li>
                • QoS 1 : Au moins une fois (confirm\u00e9).<\/li>
                • QoS 2 : Exactement une fois (confirm\u00e9 avec doublon \u00e9vit\u00e9).<\/li><\/ul><\/li><\/ol>

                  Fonctionnement de Base<\/h3>
                  1. Connexion<\/strong> :
                    • Un client (par exemple, un ESP32) se connecte au broker MQTT en utilisant un identifiant unique et, \u00e9ventuellement, un nom d’utilisateur et un mot de passe.<\/li><\/ul><\/li>
                    • Publication<\/strong> :
                      • Le client publie un message sur un topic sp\u00e9cifique.<\/li>
                      • Le broker re\u00e7oit le message et le stocke temporairement.<\/li><\/ul><\/li>
                      • Abonnement<\/strong> :
                        • Un autre client s’abonne \u00e0 un topic.<\/li>
                        • Le broker enregistre cet abonnement.<\/li><\/ul><\/li>
                        • Distribution<\/strong> :
                          • Lorsqu’un message est publi\u00e9 sur un topic, le broker distribue ce message \u00e0 tous les clients abonn\u00e9s \u00e0 ce topic.<\/li><\/ul><\/li><\/ol>

                            Avantages du MQTT<\/h3>
                            1. L\u00e9ger<\/strong> :
                              • Con\u00e7u pour les environnements \u00e0 ressources limit\u00e9es (bande passante, puissance de calcul).<\/li>
                              • Utilise un faible encombrement de donn\u00e9es.<\/li><\/ul><\/li>
                              • Fiabilit\u00e9<\/strong> :
                                • Garantit la livraison des messages gr\u00e2ce \u00e0 diff\u00e9rents niveaux de QoS.<\/li><\/ul><\/li>
                                • \u00c9volutif<\/strong> :
                                  • Peut g\u00e9rer des milliers de clients et de messages simultan\u00e9ment.<\/li><\/ul><\/li>
                                  • Facilit\u00e9 d’impl\u00e9mentation<\/strong> :
                                    • Simplicit\u00e9 du protocole facilite son impl\u00e9mentation dans diverses plateformes mat\u00e9rielles et logicielles.<\/li><\/ul><\/li><\/ol>

                                      Exemple de Code pour ESP32 utilisant PubSubClient<\/h3>

                                      Voici un exemple de code simple pour un ESP32 utilisant la biblioth\u00e8que PubSubClient<\/code> pour se connecter \u00e0 un broker MQTT, publier et s’abonner \u00e0 un topic :<\/p>

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                                      #include \n#include \n\nconst char* ssid = \"your_SSID\";\nconst char* password = \"your_PASSWORD\";\nconst char* mqtt_server = \"broker.hivemq.com\";\n\nWiFiClient espClient;\nPubSubClient client(espClient);\n\nvoid setup_wifi() {\n  delay(10);\n  Serial.println();\n  Serial.print(\"Connecting to \");\n  Serial.println(ssid);\n\n  WiFi.begin(ssid, password);\n\n  while (WiFi.status() != WL_CONNECTED) {\n    delay(500);\n    Serial.print(\".\");\n  }\n\n  Serial.println(\"\");\n  Serial.println(\"WiFi connected\");\n  Serial.println(\"IP address: \");\n  Serial.println(WiFi.localIP());\n}\n\nvoid callback(char* topic, byte* payload, unsigned int length) {\n  Serial.print(\"Message arrived on topic: \");\n  Serial.print(topic);\n  Serial.print(\". Message: \");\n  String messageTemp;\n\n  for (int i = 0; i < length; i++) { Serial.print((char)payload[i]); messageTemp += (char)payload[i]; } Serial.println(); } void reconnect() { while (!client.connected()) { Serial.print(\"Attempting MQTT connection...\"); if (client.connect(\"ESP32Client\")) { Serial.println(\"connected\"); client.subscribe(\"home\/temperature\"); } else { Serial.print(\"failed, rc=\"); Serial.print(client.state()); delay(5000); } } } void setup() { Serial.begin(115200); setup_wifi(); client.setServer(mqtt_server, 1883); client.setCallback(callback); } void loop() { if (!client.connected()) { reconnect(); } client.loop(); \/\/ Publier un message static unsigned long lastMsg = 0; unsigned long now = millis(); if (now - lastMsg > 2000) {\n    lastMsg = now;\n    String msg = \"25.3\";\n    Serial.print(\"Publishing message: \");\n    Serial.println(msg);\n    client.publish(\"home\/temperature\", msg.c_str());\n  }\n}\n<\/pre>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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                                      Conclusion<\/h5>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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                                      Le protocole MQTT est id\u00e9al pour les applications IoT en raison de sa l\u00e9g\u00e8ret\u00e9, sa fiabilit\u00e9 et sa simplicit\u00e9. Il permet une communication efficace entre des milliers de dispositifs connect\u00e9s, m\u00eame dans des environnements \u00e0 faible bande passante. La compr\u00e9hension et l’utilisation de MQTT avec des microcontr\u00f4leurs comme l’ESP32 et l’ESP8266 facilitent le d\u00e9veloppement d’applications IoT robustes et \u00e9volutives.<\/p>
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                                      Domotique – informatique – \u00e9lectronique – dictionnaire – projets<\/strong><\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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                                      Copyright 2024<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"
                                      MQTT Communication MQTT (Message Queuing Telemetry Transport) Le MQTT (Message Queuing Telemetry Transport) est un protocole de messagerie l\u00e9ger con\u00e7u pour les communications machine-\u00e0-machine (M2M) et l’Internet des objets (IoT). Il est particuli\u00e8rement utile dans des environnements o\u00f9 la bande passante est limit\u00e9e, la latence \u00e9lev\u00e9e ou la fiabilit\u00e9 critique. Voici un aper\u00e7u d\u00e9taill\u00e9 de […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_eb_attr":"","ocean_post_layout":"","ocean_both_sidebars_style":"","ocean_both_sidebars_content_width":0,"ocean_both_sidebars_sidebars_width":0,"ocean_sidebar":"","ocean_second_sidebar":"","ocean_disable_margins":"enable","ocean_add_body_class":"","ocean_shortcode_before_top_bar":"","ocean_shortcode_after_top_bar":"","ocean_shortcode_before_header":"","ocean_shortcode_after_header":"","ocean_has_shortcode":"","ocean_shortcode_after_title":"","ocean_shortcode_before_footer_widgets":"","ocean_shortcode_after_footer_widgets":"","ocean_shortcode_before_footer_bottom":"","ocean_shortcode_after_footer_bottom":"","ocean_display_top_bar":"default","ocean_display_header":"default","ocean_header_style":"","ocean_center_header_left_menu":"","ocean_custom_header_template":"","ocean_custom_logo":0,"ocean_custom_retina_logo":0,"ocean_custom_logo_max_width":0,"ocean_custom_logo_tablet_max_width":0,"ocean_custom_logo_mobile_max_width":0,"ocean_custom_logo_max_height":0,"ocean_custom_logo_tablet_max_height":0,"ocean_custom_logo_mobile_max_height":0,"ocean_header_custom_menu":"","ocean_menu_typo_font_family":"","ocean_menu_typo_font_subset":"","ocean_menu_typo_font_size":0,"ocean_menu_typo_font_size_tablet":0,"ocean_menu_typo_font_size_mobile":0,"ocean_menu_typo_font_size_unit":"px","ocean_menu_typo_font_weight":"","ocean_menu_typo_font_weight_tablet":"","ocean_menu_typo_font_weight_mobile":"","ocean_menu_typo_transform":"","ocean_menu_typo_transform_tablet":"","ocean_menu_typo_transform_mobile":"","ocean_menu_typo_line_height":0,"ocean_menu_typo_line_height_tablet":0,"ocean_menu_typo_line_height_mobile":0,"ocean_menu_typo_line_height_unit":"","ocean_menu_typo_spacing":0,"ocean_menu_typo_spacing_tablet":0,"ocean_menu_typo_spacing_mobile":0,"ocean_menu_typo_spacing_unit":"","ocean_menu_link_color":"","ocean_menu_link_color_hover":"","ocean_menu_link_color_active":"","ocean_menu_link_background":"","ocean_menu_link_hover_background":"","ocean_menu_link_active_background":"","ocean_menu_social_links_bg":"","ocean_menu_social_hover_links_bg":"","ocean_menu_social_links_color":"","ocean_menu_social_hover_links_color":"","ocean_disable_title":"default","ocean_disable_heading":"default","ocean_post_title":"","ocean_post_subheading":"","ocean_post_title_style":"","ocean_post_title_background_color":"","ocean_post_title_background":0,"ocean_post_title_bg_image_position":"","ocean_post_title_bg_image_attachment":"","ocean_post_title_bg_image_repeat":"","ocean_post_title_bg_image_size":"","ocean_post_title_height":0,"ocean_post_title_bg_overlay":0.5,"ocean_post_title_bg_overlay_color":"","ocean_disable_breadcrumbs":"default","ocean_breadcrumbs_color":"","ocean_breadcrumbs_separator_color":"","ocean_breadcrumbs_links_color":"","ocean_breadcrumbs_links_hover_color":"","ocean_display_footer_widgets":"default","ocean_display_footer_bottom":"default","ocean_custom_footer_template":"","_jetpack_memberships_contains_paid_content":false,"ocean_post_oembed":"","ocean_post_self_hosted_media":"","ocean_post_video_embed":"","ocean_link_format":"","ocean_link_format_target":"self","ocean_quote_format":"","ocean_quote_format_link":"post","ocean_gallery_link_images":"on","ocean_gallery_id":[],"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2603","post","type-post","status-publish","format-standard","hentry","category-bienvenue","entry"],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/posts\/2603","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/comments?post=2603"}],"version-history":[{"count":43,"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/posts\/2603\/revisions"}],"predecessor-version":[{"id":3282,"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/posts\/2603\/revisions\/3282"}],"wp:attachment":[{"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/media?parent=2603"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/categories?post=2603"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.domotic.phdata.fr\/domotic\/wp-json\/wp\/v2\/tags?post=2603"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}