MQTT & Pubsubclient

 MQTT & Pubsubclient

Introduction

• Basic Concepts
• Design Principles
• Example Uses
• Terminology and acronyms
• Background and History

The MQTT Protocol

• MQTT Protocol
• Conventions (generally agreed, but not formalised)
• URI Scheme

Developing Applications

• Setup and testing with brokers
• APIs and examples (see also the Libraries page)
• Techniques i.e. “how do I…?”
• Coding ideas, wanted applications, bounties, etc

Documentation & Reference

• Questions
• Technical articles
• Blog post and podcasts etc
• Useful presentations
• Server support

Some links to articles and tutorials can be found via the legacy Documentation page. — FIXME these should move into the [technical articles](technical articles) and [blog posts](blog posts) pages

The legacy Frequently Asked Questions page also has some useful material if you are getting started. — FIXME these should be migrated into the questions page

WHAT IS PUBSUBCLIENT?

It is a library provides a client for doing simple publish/subscribe messaging with a server that supports MQTT.

Limitations

• It can only publish QoS 0 messages. It can subscribe at QoS 0 or QoS 1.
• The maximum message size, including header, is 128 bytes by default. This is configurable via MQTT_MAX_PACKET_SIZE inPubSubClient.h.
• The keepalive interval is set to 15 seconds by default. This is configurable via MQTT_KEEPALIVE in PubSubClient.h.
• The client uses MQTT 3.1.1 by default. It can be changed to use MQTT 3.1 by changing value of MQTT_VERSION inPubSubClient.h.

Download

The latest version of the library can be downloaded from GitHub.

Documentation

The library comes with a number of example sketches. See File > Examples > PubSubClient within the Arduino application.

Full API Documentation