Fledge "change" Filter plugin

A filter used to only send information about an asset onwards when a particular datapoint within that asset changes by more than a configured percentage. Data is sent for a period of time before and after the change in the monitored value. The amount of data to send before and after the change is configured in milliseconds, with a value for the pre-change tiem and one for the post-change time.

It is possible to define a rate at which readings should be sent regardless of the monitored value changing. This provides an average o the values of the period defined, e.g. send a 1 minute average of the values every minute.

This filter only operates on a single asset, all other assets are passed through the filter unaltered.

Configuration Items

asset

The asset to monitor and control with this filter. This asset is both the asset that is used to look for changes and also the only asset whose data is affected by the triggered or non-triggered state of this filter.

trigger

The datapoint within the asset that is used to trigger the sending of data at full rate. This datapoint may be either a numeric value or a string. If it is a string then a change of value of the defined change percentage or greater will trigger the sending of data. If the value is a string then any change in value will trigger the sending of the data.

change

The percentage change required for a numeric value change to trigger the sendign of data. If this value is set to 0 then any change in the trigger value will be enough to trigger the sending of data.

preTrigger

The number of milliseconds worth of data before the change that triggers the sending of data will be sent.

postTrigger

The number if milliseconds after a change that triggered the sending of data will be sent. If there is a subsequent change while the data is being sent then this period will be reset and the the sending of data will recommence.

rate

The rate at which to send averages if a change does not trigger full rate data. This is defined as a number of averages for a period defined in the rateUnit, e.g. 4 per hour.

rateUnit

The unit associated with the average rate above. This may be one of "per second", "per minute", "per hour" or "per day".

Build

To build Fledge "rate" 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 ..