To define the conditions for triggering your alerts, several operators and functions are available to help you create the necessary trigger expressions.
Expression with Basic Operators
An expression can be made up of a single metric or a set of metrics linked together by operators.
Here is a list of the basic operators you can include when configuring your expressions :
Note : When entering your expressions, keep in mind that the decimal separator is the period (not the comma).
Advanced Functions
Functions allow for more complex evaluations. Below is the list of supported functions.
Function "If"
Purpose : The If function allows you to evaluate a condition and return a specific value based on the result of that evaluation. You can use it to set up alerts based on these values.
Definition : If(condition, trueValue, falseValue)
condition : The equation to evaluate.
trueValue : The value returned if the condition is true.
falseValue : The value returned if the condition is false.
Usage for Alerts :
To set up an alert, you must specify when it should be triggered, based on the result returned by the "If" function. For example :
If you want to be alerted when the function returns trueValue :
Set up the alert with the following expression:
If(condition, trueValue, falseValue) = trueValueIf you want to be alerted when the function returns falseValue:
Set up the alert with the following expression :
If(condition, trueValue, falseValue) = falseValue
Valid expression example :
Function "ifthen"
Purpose : Allows you to return a specific value if a condition is true.
Definition : ifthen([condition], [trueValue])
condition : The equation to evaluate.
trueValue : The value returned if the condition is true.
Usage for Alerts :
To set up an alert, use this function to define when it should be triggered.
For instance :
If you want to be alerted when the condition is true :
ifthen(condition, trueValue) = trueValue
Valid Expression Example :
Function "rand"
Purpose : Generates a pseudo-random number greater than or equal to 0.0 and less than 1.0.
Definition : rand()
Usage for Alerts : You can include this function in your alert expression.
Valid Expression Example with the rand() function :
Here, the user will be alerted if the sum of the value returned by their metric and a random number (rand) is greater than 200.
Function "watchdog"
Purpose : Monitors the state of data-emitting equipment (Indabox, eWon, etc.).
Definition : bool Watchdog(string [idMetrique], int [duration], bool [watchValueChange])
Functionality : If the metric [idMetrique] has not been updated for [duration] seconds, the function returns True. If the parameter [watchValueChange] = true, it also monitors changes in value between two writes. Specifically, if the last two values written to [idMetrique] are the same, the function returns True.
Equation format :
result = ( [LastRefresh] < [Now] - [Duration] ) OR ( [watchValueChange] AND [PreviousValue] = [CurrentValue] )
Usage for Alerts :
This function triggers an alert when:
The metric hasn't been updated in a certain amount of time.
If "watchValueChange" is enabled, no change in value has been detected between two writes.
Valid Expression Example :
