Bridging Data over Sockets
==========================

This example creates two separate instances of the datalogd process, and bridges a data connection
between them using :class:`~datalogd.plugins.socket_datafilter.SocketDataFilter`\ s. In this case
the running processes are on the same computer, but the connection can be made across a network
connection by selecting the correct host addresses.

A socket connection must have one server and at least one client, so one instance is configured to
start a server listening on an address (the local loopback address) and port, and the other instance
is configured as a client to connect to that port.
A 

The server configuration is:

..  literalinclude:: ../../../recipes/socket_server.config
  :language:  none
  :caption: ``recipes/socket_server.config``

.. container:: toggle

  .. container:: header

    .. code-block:: none

      $ datalogd -c recipes/socket_server.config

  .. code-block:: none

    INFO:main:Initialising DataLogDaemon.
    INFO:DataLogDaemon:Loaded config from: recipes/socket_server.config
    INFO:pluginlib:Loading plugins from standard library
    INFO:DataLogDaemon:Detected source plugins: NullDataSource, PicoTC08DataSource, RandomWalkDataSource, SerialDataSource
    INFO:DataLogDaemon:Detected filter plugins: NullDataFilter, AggregatorDataFilter, CoolingPowerDataFilter, CSVDataFilter, FlowSensorCalibrationDataFilter, JoinDataFilter, KeyValDataFilter, PolynomialFunctionDataFilter, SocketDataFilter, TimeStampDataFilter
    INFO:DataLogDaemon:Detected sink plugins: NullDataSink, FileDataSink, InfluxDB2DataSink, LoggingDataSink, MatplotlibDataSink, PrintDataSink, PyqtgraphDataSink
    INFO:DataLogDaemon:Initialising node r:RandomWalkDataSource(walkers=[[100, 10]])
    INFO:DataLogDaemon:Initialising node s:SocketDataFilter(role=server, host=127.0.0.1, port=4567)
    INFO:DataLogDaemon:Initialising node l:LoggingDataSink()
    INFO:DataLogDaemon:Connecting r:RandomWalkDataSource -> s:SocketDataFilter
    INFO:DataLogDaemon:Connecting s:SocketDataFilter -> l:LoggingDataSink
    INFO:main:Starting event loop.
    INFO:SocketDataFilter:Server started on ('127.0.0.1', 4567)

At the moment, nothing will happen, as no client(s) have connected. Open another terminal window and start a new instance using the client configuration:

..  literalinclude:: ../../../recipes/socket_client.config
  :language:  none
  :caption: ``recipes/socket_client.config``

.. container:: toggle

  .. container:: header

    .. code-block:: none

      $ datalogd -c recipes/socket_client.config

  .. code-block:: none

    INFO:main:Initialising DataLogDaemon.
    INFO:DataLogDaemon:Loaded config from: recipes/socket_client.config
    INFO:pluginlib:Loading plugins from standard library
    INFO:DataLogDaemon:Detected source plugins: NullDataSource, PicoTC08DataSource, RandomWalkDataSource, SerialDataSource
    INFO:DataLogDaemon:Detected filter plugins: NullDataFilter, AggregatorDataFilter, CoolingPowerDataFilter, CSVDataFilter, FlowSensorCalibrationDataFilter, JoinDataFilter, KeyValDataFilter, PolynomialFunctionDataFilter, SocketDataFilter, TimeStampDataFilter
    INFO:DataLogDaemon:Detected sink plugins: NullDataSink, FileDataSink, InfluxDB2DataSink, LoggingDataSink, MatplotlibDataSink, PrintDataSink, PyqtgraphDataSink
    INFO:DataLogDaemon:Initialising node r:RandomWalkDataSource(walkers=[[1.0, 0.1]])
    INFO:DataLogDaemon:Initialising node s:SocketDataFilter(role=client, host=127.0.0.1, port=4567)
    INFO:DataLogDaemon:Initialising node l:LoggingDataSink()
    INFO:DataLogDaemon:Connecting r:RandomWalkDataSource -> s:SocketDataFilter
    INFO:DataLogDaemon:Connecting s:SocketDataFilter -> l:LoggingDataSink
    INFO:main:Starting event loop.
    INFO:SocketDataFilter:Connection established to ('127.0.0.1', 4567).
    INFO:LoggingDataSink:Data received:
    INFO:LoggingDataSink:  {'type': 'randomwalk', 'id': '0', 'value': 40.0}
    INFO:LoggingDataSink:Data received:
    INFO:LoggingDataSink:  {'type': 'randomwalk', 'id': '0', 'value': 50.0}
    INFO:LoggingDataSink:Data received:
    INFO:LoggingDataSink:  {'type': 'randomwalk', 'id': '0', 'value': 50.0}
    INFO:LoggingDataSink:Data received:
    INFO:LoggingDataSink:  {'type': 'randomwalk', 'id': '0', 'value': 40.0}

Similarly, on the server instance, you should see the data sent by the client being logged to the terminal window.