/*
* This is an advanced example that demonstrates using fact priorities to optimize the rules engine.
*
* Usage:
* node ./examples/05-optimize-runtime-with-fact-priority.js
*
* For detailed output:
* DEBUG=json-rules-engine node ./examples/05-optimize-runtime-with-fact-priority.js
*/
let accountData = {
washington: {
company: 'microsoft',
status: 'terminated',
ptoDaysTaken: ['2016-12-25', '2016-04-01'],
createdAt: '2012-02-14'
},
jefferson: {
company: 'apple',
status: 'terminated',
ptoDaysTaken: ['2015-01-25'],
createdAt: '2005-04-03'
},
lincoln: {
company: 'microsoft',
status: 'active',
ptoDaysTaken: ['2016-02-21', '2016-12-25', '2016-03-28'],
createdAt: '2015-06-26'
}
}
/**
* mock api client for retrieving account information
*/
function getAccountInformation(accountId) {
var message = 'loading account information for "' + accountId + '"'
console.log(message.dim)
return new Promise((resolve, reject) => {
setImmediate(() => {
resolve(accountData[accountId])
})
})
}
let RuleEngine = require('json-rules-engine');
let engine = new RuleEngine.Engine();
/**
* Setup a new engine
*/
/**
* - Demonstrates setting high performance (cpu) facts higher than low performing (network call) facts.
*/
let microsoftRule = {
conditions: {
all: [{
fact: 'account-information',
operator: 'equal',
value: true
}, {
fact: 'date',
operator: 'lessThan',
value: 1467331200000 // unix ts for 2016-07-01; truthy when current date is prior to 2016-07-01
}]
},
event: { type: 'microsoft-employees' }
}
engine.addRule(microsoftRule)
/**
* Register listeners with the engine for rule success and failure
*/
let facts
engine
.on('success', event => {
console.log(facts.accountId + ' DID '.green + 'meet conditions for the ' + event.type.underline + ' rule.')
})
.on('failure', event => {
console.log(facts.accountId + ' did ' + 'NOT'.red + ' meet conditions for the ' + event.type.underline + ' rule.')
})
/**
* Low and High Priorities.
* Facts that do not have a priority set default to 1
* @type {Integer} - Facts are run in priority from highest to lowest.
*/
let HIGH = 100
let LOW = 1
/**
* 'account-information' fact executes an api call - network calls are expensive, so
* we set this fact to be LOW priority; it will only be evaluated after all higher priority facts
* evaluate truthy
*/
engine.addFact('account-information', (params, almanac) => {
// this fact will not be evaluated, because the "date" fact will fail first
console.log('Checking the "account-information" fact...') // this message will not appear
return almanac.factValue('accountId')
.then((accountId) => {
return getAccountInformation(accountId)
})
}, { priority: LOW })
/**
* 'date' fact returns the current unix timestamp in ms.
* Because this is cheap to compute, we set it to "HIGH" priority
*/
engine.addFact('date', (params, almanac) => {
console.log('Checking the "date" fact...')
return Date.now()
}, { priority: HIGH })
// define fact(s) known at runtime
facts = { accountId: 'washington' }
engine.run(facts).catch(console.log)
/*
* OUTPUT:
*
* Checking the "date" fact first..
* washington did NOT meet conditions for the microsoft-employees rule.
*/
/*
* NOTES:
*
* - Notice that the "account-information" fact was never evaluated, saving a network call and speeding up
* the engine by an order of magnitude(or more!). Swap the priorities of the facts to see both run.
*/
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