Collection formula structure

Use this information to understand the syntax for writing the collection formulas easily. A collection formula is a calculation that is performed against raw SNMP data. It is a combination of functions, conditions, and standard mathematical operations.

Collection formula structure

All collection formulas must have the extension .formula. If a formula file has more than one formula, save it with the extension .formulas.

Name of the formula
Typically, formula names follow a dot notation that includes the following structure:
<resource_group>.<metric_name>.<units>.formula
For example:
  • Environment.Temperature.Level.Celcius.formula
  • Network.Outbound.Broadcast.pps.formulas
function
Built-in functions that can be used in the collection formula language that can perform a calculation on the metrics and return a value. See Common functions.
when clause
Filter condition to pick from the specified values or to compare the expression to determine the value. It contains a set of key value pairs.
when resource.type == 'card' && resource.vendor =='Huawei'
Note: All string values must be in single quotation marks.
resource type
Typically, the when condition must specify the resource type from which to poll that is followed by other conditions. For example:
when resource.type == 'interface' && number(resource.ifSpeed)>429496729

SNMP bulk get

In collection formulas, for those OIDs that return arrays of values, append Array as suffix. For example:
nqaJitterStatsAvgJitterDS.octets = average(value(NQA_MIB.nqaJitterStatsAvgJitterDSArray)) when resource.vendor == 'Huawei'
Where, NQA_MIB.nqaJitterStatsAvgJitterDS is the OID. When bulk get is used on the OID, then use the suffix Array as NQA_MIB.nqaJitterStatsAvgJitterDSArray.
  • The expression, value(NQA_MIB.nqaJitterStatsAvgJitterDSArray) returns an array of values.
  • To access the first element in the list, use value(NQA_MIB.nqaJitterStatsAvgJitterDSArray)[0].
  • You can also use more advanced JavaScript array methods such as .reduce() can be used on Java.from(value(NQA_MIB.nqaJitterStatsAvgJitterDSArray)).
  • Predefined functions such as max, min, sum, count, and average can also be used with these arrays.
  • CPU.Utilization.Percent.formula
    CPU.Utilization.Percent = value(CISCO_PROCESS_MIB.cpmCPUTotal5minRev) when resource.type == 'cpu' && resource.vendor =='Cisco'
  • Network.Inbound.Broadcast.pps.formulas
    Network.Inbound.Broadcast.pps = positive(delta(IF_MIB.ifHCInBroadcastPkts))/duration(IF_MIB.ifHCInBroadcastPkts)*100 when resource.type == 'interface' && number(resource.ifSpeed)>4294967295
Network.Inbound.Broadcast.pps = positive(delta(IF_MIB.ifInBroadcastPkts))/duration(IF_MIB.ifInBroadcastPkts)*100 when resource.type == 'interface' && number(resource.ifSpeed)<4294967295