Internet of Things Relay: Giving Voice to Your Things
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README.rst

IoT Relay: Giving Voice to Your Things

Release v1.2.2

In greater and greater numbers, "things" are capable of gathering data about their environment. These things have an interface to retrieve the measurements being taken but contain no way of pushing this data to the Internet. For example, home weather stations often contain only a USB interface and no network capability. Other devices may have network capability, such as ZigBee®, but still don't have a direct way to send data to Internet connected hosts.

Internet of Things Relay is an application and framework for gathering data from sources and relaying it to destinations. It is somewhat like publish/subscribe except that it's geared more toward devices that are unable to initiate a connection (they must be polled to get at their data).

IoT Relay provides basic setup and matches data sources with interested handlers. The rest of the work is left to plugins.

Installation

IoT Relay is available via PyPI.

$ pip install iotrelay

It is also necessary to create an (initially empty) ini-style file: ~/.iotrelay.cfg.

[itorelay]

Plugins

Before IoT Relay can do anything useful, it needs plugins. There are plugin types: source and handler. Source plugins generate data. Handler plugins handle or do something with data that source plugins produce. These definitions are intended to be open-ended. Although IoT Relay was developed with the intention of relaying time-series type data between remote sources and remote destinations, a handler could instead view each datum as an event and trigger some action. Likewise, data source plugins do not have to simply pass the data they are collecting. They may process the data in some way before making it available to interested handlers.

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.

Running IoT Relay

Start IoT Relay with the following command:

$ iotrelay

License

IoT Relay is licensed under The BSD 2-Clause License.