FrequencyConstraint Function

Produce a point only after a number of events have been triggered (and consumed). This constraint is mostly useful in conjunction with others.

For an example application that allows login by UID but not by email, we're led to believe it's confusing the users. We want to track if people are repeatedly failing to login due to invalid UIDs.

One way to capture that is by checking if they fail to login 3 times in 90 seconds.

import { FrequencyConstraint, TypeConstraint } from 'full-metal-alchemy'

const metric = {
  constraints: [
    TypeConstraint([ 'login-failed--invalid-uid' ]),

    // 3 times
    FrequencyConstraint(3),

    // within 30 seconds of each other
    ProximityConstraint({
      period: Period.seconds(30)
    })
  ]
}