Fledge SimpleExpression notification rule plugin

An expression based notification rule plugin:

The configuration items are:

• "asset" is the asset name for which notifications will be generated.
• "expression" is the expression to evaluate in order to send notifications

Note this plugin is designed to work with a single asset name.

Example:

{
    "asset": {
            "description": "The asset name for which notifications will be generated.",
            "name": "modbus"
    },
    "expression": {
            "description": "The expression to evaluate",
            "name": "Expression",
            "type": "string",
            "value": "humidity > 50"
    }
}

Expression is composed of datapoint values within given asset name.

There is no need to provide datapoint names because names and values are dynamically added when "plugin_eval" is called.

If the value of expression is true, then the notification is sent.

Expression may contain any of the following...

• Mathematical operators (+, -, *, /, %, ^)
• Functions (min, max, avg, sum, abs, ceil, floor, round, roundn, exp, log, log10, logn, pow, root, sqrt, clamp, inrange, swap)
• Trigonometry (sin, cos, tan, acos, asin, atan, atan2, cosh, cot, csc, sec, sinh, tanh, d2r, r2d, d2g, g2d, hyp)
• Equalities & Inequalities (=, ==, <>, !=, <, <=, >, >=)
• Logical operators (and, nand, nor, not, or, xor, xnor, mand, mor)

The plugin uses the C++ Mathematical Expression Toolkit Library by Arash Partow and is used under the MIT licence granted on that toolkit.

Build

To build Fledge "SimpleExpression" notification rule C++ plugin, in addition fo Fledge source code, the Notification server C++ header files are required (no .cpp files or libraries needed so far)

The path with Notification server C++ header files cab be specified only via NOTIFICATION_SERVICE_INCLUDE_DIRS environment variable.

Example:

$ export NOTIFICATION_SERVICE_INCLUDE_DIRS=/home/ubuntu/source/fledge-service-notification/C/services/notification/include

$ 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 ..