uMQTT is a micro - micro as in lightweight - MQTT client library and accompanying tool kit that supports debugging of MQTT packets. The uMQTT library is equally suited for use on low powered embedded devices along with power hungry servers, and as such, provides a consistent API for developing a wide range of MQTT devices and applications.

uMQTT provides a client MQTT library that, though the uMQTT API, provides full MQTT support to new or existing applications.

The core of the uMQTT library is contained in the uMQTT.c and uMQTT.h files, with the following files providing additional support:

uMQTT_client.c inc/uMQTT_client.h

• Basic client functions.

uMQTT_linux_client.c inc/uMQTT_linux_client.h

• Extended client functions that implement Linux support.

uMQTT_helper.c inc/uMQTT_helper.h

• uMQTT helper functions - mostly for printing.

uMQTT provides a number of standard applications as defined below.

uMQTT provides two Linux client applications:

Application to publish messages to a given topic to an MQTT broker.

The following command provides further information.

bin/uMQTT_pub --help

Application to subscribe to topics on an MQTT broker.

The following command provides further information.

bin/uMQTT_sub --help

Tool that takes a packet/packets as a command line argument, decodes and prints details of the packet in human readable form.

The following command provides further information.

bin/uMQTT_print_packet --help

Tool for generating MQTT packets on the command-line. Packets are entered as arguments, before being encoded and printed in both hex and raw binary form.

The following command provides further information.

bin/uMQTT_gen_packet --help

Provides a number of basic unit tests designed to ensure the core uMQTT library functions correctly - albeit, incomplete.

Prints all packets supported by the uMQTT_library - all MQTT packets - and confirms that these match what is expected.

Tests the publish functionality of the uMQTT library. uMQTT_pub_test takes a single, optional, argument, the broker IP address. If this is omitted, the test will attempt to connect to a broker on localhost.

Tests the subscribe functionality of the uMQTT library. uMQTT_sub_test takes a single, optional, argument, the broker IP address. If this is omitted, the test will attempt to connect to a broker on localhost.

Test scripts are located in scripts/tests/ and provide additional functional testing, such as memory leak testing.

Bash script that test the libraries ability to generate MQTT packets.

Perl script that tests a number of the existing binaries for memory leaks and general memory errors, using valgrind. This script takes a single, optional, argument, the broker IP address. If this is omitted, the test will attempt to connect to a broker on localhost.

On Linux based platforms, building the uMQTT tool kit is as simple as typing make. Binaries are then created in the bin/ folder.

make debug builds the uMQTT tool kit with debug included. This also enables debug printing.

make docs builds the Doxygen documentation, which can be viewed by pointing a browser at docs/html/index.html.

The following platforms have been tested:

• Linux
• Contiki
• AVR

Currently, uMQTT does not support QoS levels greater than 0, and excrypted authentication, although, support for these features are underway.