DMN Lambda

DMN

DMN™(Decision Model and Notation™) is an OMG standard to develop complex rules engine. This standard provides some graphical components designer can use easily for building complex rule system. Designer is mainly a business analyst, because DMN is a low-code standard.

Requirements

• AWS Account with Lamdba Function Grant

Compile

This sample uses Maven configuration file. Execute the command below to compile/build.

mvn clean package

Deploy

Here is the command to deploy the DMN Lambda function to AWS.

sam deploy  --confirm-changeset -t src/main/aws/sam.tmpl.yaml

This command will create all stuffs into AWS infrastructure for executing the Lambda.

Lambda URL

To retrieve URL Lambda.

export AWS_STACK_NAME=dmn-lambda-sam

aws apigatewayv2 get-apis --output json --query "Items[?Tags.\"aws:cloudformation:stack-name\"=='${AWS_STACK_NAME}'].ApiEndpoint | [0] "  | jq -r

You should get this kind of output.

https://AAABBBDDDCCCC.execute-api.AWS_REGION.amazonaws.com

Execute this command once for exporting DMN_LAMBDA_URL to bash env

export DMN_LAMBDA_URL=`aws apigatewayv2 get-apis --output json --query "Items[?Tags.\"aws:cloudformation:stack-name\"=='${AWS_STACK_NAME}'].ApiEndpoint | [0] "  | jq -r`

CURL Execution

Execute a curl command

curl ${DMN_LAMBDA_URL}/KYC -X POST  -H 'Accept: application/json'  -H 'Content-Type: application/json'   --data-raw '{"PEP":true,"Amount":100000,"Fiscal Residency":"FR"}' | jq

{
    "Amount Rule": "HIGH",
    "Level to Int": "function Level to Int( Level )",
    "Max Level": "function Max Level( list of Level )",
    "KYC": {
        "Score": "HIGH",
        "Level": 150
    },
    "Fiscal Residency Rule": "LOW",
    "Amount": 100000,
    "Int to Level": "function Int to Level( Int )",
    "PEP Rule": "HIGH",
    "PEP": true,
    "Fiscal Residency": "FR",
    "Level to Score": "function Level to Score( Level )"
}

Newman (Postman) Execution

A Postman collection is available inside src/main/postman folder. Newman provides a command line tool to execute a postman collection. Don’t forget to pass some AWS Credential too.

newman run  src/main/postman/KYC-DMN.postman_collection.json  --env-var DMN_LAMBDA_URL=${DMN_LAMBDA_URL} --env-var  AWS_ACCESS_KEY_ID=${AWS_ACCESS_KEY_ID} --env-var AWS_SECRET_ACCESS_KEY=${AWS_SECRET_ACCESS_KEY} --env-var  AWS_DEFAULT_REGION=${AWS_DEFAULT_REGION} --verbose

Here is the Newman output.

newman

KYC-DMN

→ Call DMN
  POST https://AAABBBDDDCCCC.execute-api.AWS_REGION.amazonaws.com/KYC
  200 OK ★ 229ms time ★ 721B↑ 534B↓ size ★ 12↑ 5↓ headers ★ 0 cookies
  ┌ ↑ raw ★ 52B
  │ {"PEP":true,"Amount":100000,"Fiscal Residency":"FR"}
  └
  ┌ ↓ application/json ★ text ★ json ★ utf8 ★ 352B
  │ {"Amount Rule":"HIGH","Level to Int":"function Level to Int( Level )","Max Level":"function Max Level( list of Level )","KYC":{"Score":"HIGH","Level":150},"Fiscal Residency Rule":"LOW","Amount":1000
  │ 00,"Int to Level":"function Int to Level( Int )","PEP Rule":"HIGH","PEP":true,"Fiscal Residency":"FR","Level to Score":"function Level to Score( Level )"}
  └
  prepare   wait   dns-lookup   tcp-handshake   ssl-handshake   transfer-start   download   process   total
  78ms      9ms    37ms         24ms            58ms            89ms             8ms        481µs     307ms

  ✓  response must be valid and have a body

┌─────────────────────────┬────────────────────┬───────────────────┐
│                         │           executed │            failed │
├─────────────────────────┼────────────────────┼───────────────────┤
│              iterations │                  1 │                 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│                requests │                  1 │                 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│            test-scripts │                  2 │                 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│      prerequest-scripts │                  1 │                 0 │
├─────────────────────────┼────────────────────┼───────────────────┤
│              assertions │                  1 │                 0 │
├─────────────────────────┴────────────────────┴───────────────────┤
│ total run duration: 394ms                                        │
├──────────────────────────────────────────────────────────────────┤
│ total data received: 352B (approx)                               │
├──────────────────────────────────────────────────────────────────┤
│ average response time: 229ms [min: 229ms, max: 229ms, s.d.: 0µs] │
├──────────────────────────────────────────────────────────────────┤
│ average DNS lookup time: 37ms [min: 37ms, max: 37ms, s.d.: 0µs]  │
├──────────────────────────────────────────────────────────────────┤
│ average first byte time: 89ms [min: 89ms, max: 89ms, s.d.: 0µs]  │
└──────────────────────────────────────────────────────────────────┘