Fledge "scale-set" C++ Filter plugin

Selectively apply a set of scale and offset values to data readings.

A JSON document configures the set of scale factors and offset values to add to readings. Each scale and offset value is associated with a regular expression whcih is matches against the asset name of the reading in the asset. Optionally a datapoint regular expression may also be given, this is used to match the datapoint within a matching asset.

Caution, if multiple regular expressions match a single asset and datapoint then all of the scale and offset values will be applied to the asset/datapoint.

Configuration

The filter supports the following configuration items:

enable

A switch to control if the filter should take effect or not

factors

A JSON document which contains an array of scale factors to apply. Each element in the arary is a JSON object with the following properties:

asset

A regular expression that should match the asset name

datapoint

A regular expression that should match the data point within the asset

scale

The scale factor to apply to the matching asset and data point

offset

An offset value to apply to the matching asset and data point

{ "factors" : [
     {
       "asset"     : "environment",
       "datapoint" : "temperature",
       "scale"     : 1.8,
       "offset"    : 32
     },
     {
       "asset"     : "environment",
       "datapoint" : "humidity",
       "scale"     : 0.1,
       "offset"    : 0
     }
  ]
}

Build

To build Fledge "scale-set" C++ filter plugin:

$ mkdir build
$ cd build
$ cmake ..
$ make

• By default the Fledge develop package header files and libraries are expected to be located in /usr/include/fledge and /usr/lib/fledge
• If FLEDGE_ROOT env var is set and no -D options are set, the header files and libraries paths are pulled from the ones under the FLEDGE_ROOT directory. Please note that you must first run 'make' in the FLEDGE_ROOT directory.

You may also pass one or more of the following options to cmake to override this default behaviour:

• FLEDGE_SRC sets the path of a Fledge source tree
• FLEDGE_INCLUDE sets the path to Fledge header files
• FLEDGE_LIB sets the path to Fledge libraries
• FLEDGE_INSTALL sets the installation path of Random plugin

NOTE:

• The FLEDGE_INCLUDE option should point to a location where all the Fledge header files have been installed in a single directory.
• The FLEDGE_LIB option should point to a location where all the Fledge libraries have been installed in a single directory.
• 'make install' target is defined only when FLEDGE_INSTALL is set

Examples:

• no options

  $ cmake ..

• no options and FLEDGE_ROOT set

  $ export FLEDGE_ROOT=/some_fledge_setup

  $ cmake ..

• set FLEDGE_SRC

  $ cmake -DFLEDGE_SRC=/home/source/develop/Fledge ..

• set FLEDGE_INCLUDE

  $ cmake -DFLEDGE_INCLUDE=/dev-package/include ..

• set FLEDGE_LIB

  $ cmake -DFLEDGE_LIB=/home/dev/package/lib ..

• set FLEDGE_INSTALL

  $ cmake -DFLEDGE_INSTALL=/home/source/develop/Fledge ..

  $ cmake -DFLEDGE_INSTALL=/usr/local/fledge ..