Cumulocity MQTT Python agent

A simple python agent connecting to Cumulocity via MQTT

Prerequisites

1. Install python 3.x
2. Install libraries from requirements.txt
3. Create a folder ".c8y-agent" in your home directory and copy the agent.ini from the config folder there
4. Set the correct bootstrap password (If you do not know it ask [email protected])
5. Upload the smartrest.json to the SmartREST templates in your tenant (you can use the import functionality)

Running the agent

The agent can be started

python main.py start

stopped

python main.py stop

and restarted

python main.py restart

You can also run the agent with debug which will not create the daemon and run it in the process directly

python main.py debug

Bootstrapping

The agent uses normal device bootstrap. The serial that is used for bootstrapping is printed at the start of the agent. The credentials are later stored in the agent.ini file. To re-register the agent to a different tenant you can simply delete those lines.

Extending the agent

The agent knows three types of classes that it will automatically load and include from the "agentmodules" directory.

1. Sensors

    class Sensor:
      __metaclass__ = ABCMeta
   
      def __init__(self, serial):
        self.serial = serial
   
      '''
      Returns a list of SmartREST messages. Will be called every iteration of the main loop.
      '''
      @abstractmethod
      def getSensorMessages(self): pass
   

   Sensors are periodically polled by the main loop and published.

2. Listeners

    class Listener:
      __metaclass__ = ABCMeta
   
      def __init__(self, serial, agent):
        self.serial = serial
        self.agent = agent
   
      '''
      Callback that is executed for any operation received
      '''
      @abstractmethod
      def handleOperation(self, message): pass
   
      '''
      Returns a list of supported operations
      '''
      @abstractmethod
      def getSupportedOperations(self): pass
   
      '''
      Returns a list of supported SmartREST templates (X-Ids)
      '''
      @abstractmethod
      def getSupportedTemplates(self): pass
   

   Listeners are called whenever there is a message received on a subscribed topic.

3. Initializers

    class Initializer:
      __metaclass__ = ABCMeta
   
      def __init__(self, serial):
        self.serial = serial
   
      '''
      Returns a list of SmartREST messages. Will be called at the start of the agent
      '''
      @abstractmethod
      def getMessages(self): pass
   

   Initializers are only called once at the start of the agent.

You can take a look at the two example modules for how it can be used.

Log

The logfile can be found in the .c8y-agent directory that you created

Notes

I tested the agent so far only under Ubuntu 16.04 x64 with python 3.5.2