There are two aggregation operators used in the priority calculation formula, Sum and Difference. The Sum operator adds the values of all of the elements that it contains. The Difference operator subtracts the sum of all of the values of the subsequent elements from the value of the first element it contains.
Both operators have two attributes, maxValue and weight.
MaxValue Attribute
MaxValue is used to clip the result after the operator aggregation is carried out. After aggregating, the result is also normalized, which is achieved by dividing the result with MaxValue. For example, if we have an element like
<SUM maxValue = 100>
and it has two child elements, each of which evaluate to 80, the pre-normalization value will still be 100 and not 160. After normalization, the final result for this example will be 1. Similarly, there is an implied lower limit or minimum value of zero on these elements.
Weight Attribute
The Weight attribute is used to scale the result after operator aggregation and normalization are carried out. So, as in the example previously described, if the aggregating element was:
<SUM maxValue = 100 weight = 7>
the result after normalization is 1, and after scaling, it becomes 7.
Each of the formulas have an implied maxValue of 10 since each of the four fields in the alert take values in the range 0-10 (inclusive).