How to configure PublishMQTT and ConsumeMQTT processors

[#1]

1) Enable MQTT extension

Please reference https://github.com/apache/nifi-minifi-cpp/blob/master/README.md

cmake -DENABLE_MQTT=TRUE ..

2) Common Processor Properties

Broker URI: The URI to use to connect to the MQTT broker

Session state: Whether to start afresh or resume previous flows, default to true

Client ID: MQTT client ID to use

Username: Username to use when connecting to the broker

Password: Password to use when connecting to the broker

Keep Alive Interval: Defines the maximum time interval between messages sent or receive, default to 60 sec

Connection Timeout: Maximum time interval the client will wait for the network connection to the MQTT server, default to 30 sec

Quality of Service: The Quality of Service(QoS) to send the message with. Accepts three values 0, 1, 2

Topic: The topic to publish or subscribe the message

3) PublishMQTT Processor Properties

Retain: Retain MQTT published record in broker, default to false

Max Flow Segment Size: Maximum flow content payload segment size for the MQTT record

4) Relationships

success: Any FlowFile that is successfully sent to/received from MQTT will be routed to this Relationship

failure: Any FlowFile that cannot be sent to MQTT will be routed to this Relationship

5) Please refer to https://www.eclipse.org/mosquitto/download/ for MQTT broker

6) Please refer to http://www.eclipse.org/paho/clients/c/ for libmqtt extension

7) Please refer to http://mqtt.org/ for latest MQTT spec