wolfMQTT is an MQTT client that has the capability to connect to the IBM Watson IoT cloud platform broker. This is useful as IBM's cloud platform allows users to potentially offload large amounts of data and/or computation to the cloud that is provided.
wolfMQTT comes ready with an example application titled "wiot" that shows users one way to communicate with the IBM Watson IoT broker. To use this example, all that needs to be done is to build the wolfMQTT library and then execute the wiot example.
An IBM Recipe that shows the process can be viewed here.