pyramid

JSON-based Business Rules Engine

Installing

npm install pyramid-rules-engine

Modules

pyramid contains serveral modules - loader, validator, stores, loggers, operators, rules.

Loader

Loader is responsible for loading data files such as data objects and input json file. If data is not found, the rule engine would stop immediately and throw related errors.

Validator

Validator is responsible for validating the input source loaded by Loader. The scope includes rule properties, rule id and rule conditions.

Rule Properties

Properties such as id, name, when are mandatory.

Rule ID

Rule ID must be unqiue.

Rule Conditions

Rule conditions are objects defined in when. Each object can contain other nested objects.

$AND and $OR

If you want to define a condition with a logical operators such as AND and OR. You have to use an array with the attribute $and and or. Each array could only contain two objects. Nested objects are also supported.

Condition

A condition is an an object with three attributes - fact, operator and value

fact: The target attribute which is being used to evalute. It has to be started with a data object, such as $$bankruptcy.amountOwed. Another example for a data object is inside another object would be $$applicant.$$applicantAddress.zipcode.

``operator`: Please refer to Operators below.

value: The value is used to compare with the one in input file.

A condition will be evaluted and return a boolean indicating if the condition is met with the defined criteria.

Stores

Stores is responsible for centralizing stores such as DATA_OBJECTS_STORE, RULES_STORE, INPUT_FILE_STORE and RESULT_STORE

Loggers

Loggers is responsible for logging. Two loggers are available.

Normal Logger:

logger('Normal Logger');

Error Logger:

errorLogger('Error Logger');

Operators

Operators is responsible for performing mathematical operations. Six operators are available which are ==, >=, <=, >, < and !=.

Rules

Rules is responsible for initializing the rule engine, process and evalute the defined rules based on the input file and return the result.

Configuration

• Create a file named pyramid.cfg
• Define the paths for DATA_OBJ_DIR, RULES_DIR and INPUT_FILE
• Example:

{
    "DATA_OBJ_DIR": "../example/loan-application/data_objects/",
    "RULES_DIR": "../example/loan-application/rules/",
    "INPUT_FILE": "../example/loan-application/input.json"
}

Define data object

• Create a file with an extension .data under DATA_OBJ_DIR
• A data object has to be started with $$
• Example:

{
    "$$applicant": {
        "type": "object",
        "value": {
            "age": "number",
            "applicantAddress": "$$applicantAddress"
        }
    }
}

Define rule

• Create a file with an extension .rule under RULES_DIR
• Example: Sample Rule

{
    "id": 1,
    "name": "checkApplicantAge",
    "description": "Check applicant age ",
    "when": [
        {
            "fact": "$$applicant.age",
            "operator": ">=",
            "value": 25
        }
    ]
}

• Example 2: Complex Rule

{
    "id": 0,
    "name": "Loan Application",
    "description": "Check if loan application is approved or rejected ",
    "when": [
        {
            "$and": [
                {
                    "fact": "$$applicant.age",
                    "operator": "<=",
                    "value": 25
                },
                {
                    "$or": [
                         {
                            "fact": "$$bankruptcy.amountOwed",
                            "operator": "==",
                            "value": 100000
                        },
                        {
                            "fact": "$$incomeSource.amount",
                            "operator": ">=",
                            "value": 30000
                        }
                    ]
                }
            ]
        },
        {
            "fact": "$$applicant.$$applicantAddress.zipcode",
            "operator": "==",
            "value": "5223"
        },
        {
            "fact": "$$coApplicant.name",
            "operator": "==",
            "value": "Milena Sears"
        }
    ]
}

Define input file

• Create a file with an extension .json as INPUT_FILE
• Example:

{
    "applicant": {
        "name": "Zayna Wainwright",
        "age": 24,
        "occupation": "N/A",
        "applicantAddress": {
            "address": "2752  Star Route",
            "zipcode": "60634"
        }
    }, 
    "bankruptcy": {
        "amountOwed": 3000
    },
    "incomeSource": {
        "amount": 35000
    },
    "coApplicant": [
        {
            "name": "Milena Sears",
            "applicantReferralCode": "CA1234"
        },
        {
            "name": "Clement Simpson",
            "applicantReferralCode": "CA2345"
        }
    ]
}

Run

node pyramid.js <PYRAMID_CFG_PATH>

Example

The example can be found in folder example

Example Result

------------------------------------------------------------------------
[INFO] Load Initialization
------------------------------------------------------------------------
[INFO] Loading Configuration file
[INFO] Loading Data Objects: ../example/loan-application/data_objects/
[INFO] Loading data object ../example/loan-application/data_objects/applicant.data
[INFO] Loading data object ../example/loan-application/data_objects/applicantAddress.data
[INFO] Loading data object ../example/loan-application/data_objects/bankruptcy.data
[INFO] Loading data object ../example/loan-application/data_objects/coApplicant.data
[INFO] Loading data object ../example/loan-application/data_objects/coApplicantObject.data
[INFO] Loading data object ../example/loan-application/data_objects/incomeSource.data
[INFO] Loading Rules ../example/loan-application/rules/
[INFO] Loading rule file ../example/loan-application/rules/checkApplicantAge.rule
[INFO] Loading rule file ../example/loan-application/rules/loanApplication.rule
[INFO] Loading Input File ../example/loan-application/input.json
------------------------------------------------------------------------
[INFO] Validator Initialization
------------------------------------------------------------------------
[INFO] Validation Finished. No errors found
------------------------------------------------------------------------
[INFO] Rule Engine Initialization
------------------------------------------------------------------------
[INFO] Processing Rule 1 - Check Applicant Age
[INFO] Processing Rule 0 - Loan Application
------------------------------------------------------------------------
[INFO] Rule Engine Result Summary
------------------------------------------------------------------------
[INFO] Rule 1 (Check Applicant Age) : SUCCESS
[INFO] Rule 0 (Loan Application) : FAILURE