Data Source Sample Plugin

A data source definition is a class which provides a get_reading() method and a constructor which accepts a config parameter. The get_reading() method must return one or more instances of the Reading() class or None. In this example, create a file called iotrelay_sample_source.py and enter the following code.

# iotrelay_sample_source.py

import random
from iotrelay import Reading


class DataSource(object):
    def __init__(self, config):
        self.config = config

    def get_readings(self):
        return Reading('sample', random.randint(1, 100))

IoT Relay uses setuptools to find plugins registered in the iotrelay group. Datasources should use the entry-point name source. In the same directory as iotrelay_sample_source.py, the following code should be placed in setup.py.

# setup.py

from setuptools import setup


setup(name='iotrelay-sample-source',
      install_requires=['iotrelay'],
      py_modules=['iotrelay_sample_source'],
      entry_points={
          'iotrelay': ['source=iotrelay_sample_source:DataSource']
      }
)

Install the source plugin by typing:

$ python setup.py install

Data Handler Sample Plugin

Like the previous example, create a new directory with two files:

# iotrelay_sample_handler.py

class Handler(object):
    def __init__(self, config):
        self.config = config

    def set_reading(self, reading):
        print(reading)


# setup.py

from setuptools import setup


setup(name='iotrelay-sample-handler',
      install_requires=['iotrelay'],
      py_modules=['iotrelay_sample_handler'],
      entry_points={
          'iotrelay': ['handler=iotrelay_sample_handler:Handler']
      }
)

Install the handler plugin by typing:

$ python setup.py install

Plugin Configuration

The minimal source plugin used in this example does not require any configuration. The ‘reading types’ option in a handler’s configuration specifies which reading types a handler will receive. In order to receive readings from the ‘iotrelay-sample-source’ plugin, the ‘reading type’ option in the iotrelay-sample-handler would be ‘sample’. This corresponds to the reading_type attribute set by the Reading constructor when get_readings() was called.

The section names correspond directly to the plugin names, as defined in setup.py.

; ~/.iotrelay.cfg

[iotrelay]

[iotrelay-sample-source]
[iotrelay-sample-handler]
reading types = sample

Any options specified in each plugins section will be passed to that plugin’s constructor during initialization.