mqtt_util.hpp File Reference

Utilities for receiving and sending MQTT commands. More...

#include <ArduinoJson.h>
#include <string>
#include "SDReader.hpp"

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Functions
void	process_command (string command, string message)
	Process a command execute it.
void	callback (char *topic, byte *message, unsigned int length)
	Called when MQTT message is passed to the device by the broker.

Detailed Description

Utilities for receiving and sending MQTT commands.

Utilities and interface for receiving MQTT messages from the broker. Also used to request data logged to the uSD card from the device.

1. defines a basic callback to attach to the MQTT client object to handle received messages.
2. defines a function to check and take proper action on commands received via MQTT.

Author

Garrett Wells

Function Documentation

callback()

void callback	(	char *	topic,
		byte *	message,
		unsigned int	length
	)

Called when MQTT message is passed to the device by the broker.

Prints command and message to serial interface, then parses the MQTT packet and processes the command.

Commands are defined as a anything published to the datagator/cmd/# topic tree. The # symbol is an MQTT regex glob symbol that matches all MAC addresses. It tells the DG to subscribe to all commands published to ALL DGs.

The command is only processed in process_command(...) if the MAC address in the topic, such as datagator/cmd/AC:45... matches the MAC of this DG.

Parameters

[in]	topic	The topic the message was published on
[in]	message	The message in the MQTT packet
[in]	length	The length of the message

process_command()

void process_command	(	string	command,
		string	message
	)

Process a command execute it.

Checks the command, if the command matches one of the known commands, then the message is processed. The message contains details about how the command should be carried out.

Parameters

[in]	command	The command as a string.
[in]	message	The body/message sent with the command.