eclipse-paho/paho.mqtt.embedded-c

Free

Paho MQTT C client library for embedded systems. Paho is an Eclipse IoT project (https://iot.eclipse.org/)

FreeFree tier

Type

Open Source

Company

Eclipse Foundation

Visit Website GitHub (38 stars)

About eclipse-paho/paho.mqtt.embedded-c

Eclipse Paho MQTT C/C++ client library designed for embedded platforms. Part of the Eclipse IoT project, it provides three sub-projects: MQTTPacket (low-level C library for MQTT packet serialization/deserialization), MQTTClient (higher-level C++ client with pluggable networking support for platforms like Linux, Arduino, and mbed), and MQTTClient-C (a C equivalent of the C++ client for platforms not supporting C++). The library is dual-licensed under EPL and EDL, allowing flexible use and distribution. Build via CMake with automated testing on Travis-CI. Includes samples, Doxygen documentation, and debug tracing via the MQTT_DEBUG preprocessor definition.

Key Features

Three sub-projects: MQTTPacket (low-level serialization), MQTTClient (C++ with pluggable networking), MQTTClient-C (C equivalent)

Dual-licensed under EPL and EDL for flexible use and distribution

Pluggable networking support in C++ client: Linux, Arduino, mbed

CMake-based build system with automated Travis-CI testing

Debug tracing of MQTT packets via MQTT_DEBUG preprocessor definition

Porting guide and sample code provided for integration

Doxygen configuration files for API documentation

Pros & Cons

Pros

Lightweight and minimal dependencies, especially MQTTPacket
Supports both C and C++, accommodating diverse embedded toolchains
Part of the well-established Eclipse Paho project with community support
Dual-license (EPL/EDL) eases integration into proprietary projects
Documentation including samples, porting guide, and Doxygen

Cons

MQTTPacket requires user to implement network I/O; no built-in transport
C++ client may not be suitable for platforms lacking C++ compilers
Limited to MQTT protocol; no support for other IoT messaging protocols

Best For

Embedded IoT devices requiring MQTT communicationResource-constrained platforms (Arduino, mbed) wanting a lightweight MQTT clientLinux-based embedded systems needing C or C++ MQTT supportPrototyping and production use in Eclipse IoT ecosystem

FAQ

What are the main sub-projects in this library?

There are three: MQTTPacket (low-level serialization/deserialization), MQTTClient (higher-level C++ with pluggable networking), and MQTTClient-C (a C equivalent of MQTTClient).

What license is used?

The library is dual-licensed under the Eclipse Public License (EPL) and Eclipse Distribution License (EDL). You can choose which license to use.

Which platforms are supported?

The C++ client includes networking implementations for Linux, Arduino, and ARM mbed. The C client is designed for platforms not supporting C++. The low-level MQTTPacket can be used on any platform with a C compiler.

How do I build the library?

Use CMake: create a build directory, run cmake .., then make. A Travis-CI configuration is included for automated build testing on Linux.

Is there debugging/tracing support?

Yes, set the MQTT_DEBUG preprocessor definition to enable debug tracing of MQTT packets sent and received.