In microservices approach, software is composed of small independent services that communicate over well-defined APIs. Serveless apps are architected such that developers can focus on their core competency—writing the actual business logic instead of responsibilities like operating system (OS) access control, OS patching, provisioning, right-sizing, scaling, and availability. In serverless architecture, by implementing the microservices using AWS APIGateway, AWS Lambda and AWS DynamoDB underlying AWS platform manages those responsibilities for you.

Purpose of this project is to provide serverless microservice implementation using the following technologies.

• AWS Services
  • AWS API Gateway, Lambda and DynamoDB
• Programming Language
  • JAVA 8
• Build Tool
  • Gradle
• Unit Testing
  • Junit, Hamcrest, Mockito

• Create an AWS account [https://aws.amazon.com/]
• Configure AWS CLI [http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-started.html]

Following diagram shows the overall architecture of the Microservice.

APIGateway uses Lambda proxy integration, by doing so requests will be proxied to Lambda.

Please refer following diagram

APIGateway proxied the contents of the client’s HTTPS request to Lambda function for execution. Those contents include request metadata, request headers, and the request body.

Following shows a sample a proxied request for the resource /v1/employee for the POST operation.

{
    "resource": "/v1/employee",
    "path": "/v1/employee",
    "httpMethod": "POST",
    "headers": null,
    "queryStringParameters": null,
    "pathParameters": null,
    "stageVariables": null,
    "requestContext": {
        "path": "/v1/employee",
        "accountId": "",
        "resourceId": "",
        "stage": "test-invoke-stage",
        "requestId": "test-invoke-request",
        "identity": {
            "cognitoIdentityPoolId": null,
            "accountId": "",
            "cognitoIdentityId": null,
            "caller": "",
            "apiKey": "test-invoke-api-key",
            "sourceIp": "test-invoke-source-ip",
            "accessKey": "",
            "cognitoAuthenticationType": null,
            "cognitoAuthenticationProvider": null,
            "userArn": "",
            "userAgent": "Apache-HttpClient/4.5.x (Java/1.8.0_144)",
            "user": ""
        },
        "resourcePath": "/v1/employee",
        "httpMethod": "POST",
        "apiId": "js4o6av9ob"
    },
    "body": "[  \r\n   {  \r\n      \"id\":\"0001\",\r\n      \"type\":\"SWE\",\r\n      \"firstName\":\"XYZ\",\r\n      \"lastName\":\"PQR\",\r\n      \"addressLine1\":\"Address1\",\r\n      \"addressLine2\":\"Address2\",\r\n      \"postalCode\":\"900\",\r\n      \"city\":\"Colombo\",\r\n      \"countryCode\":\"SL\",\r\n      \"country\":\"Sri Lanka\"\r\n   }\r\n]",
    "isBase64Encoded": false
}

This project includes a complete Lambda proxy implementation lambda\lambda-proxy-api using JAVA 8 with unit testing. Lambda function handler will invoke the appropriate invoker based on the request resource and httpMethod.

Using the AWS console create an IAM Role lambda_basic_execution for the Lambda function execution. For this scenario two policies were attached to the role arn:aws:iam::aws:policy/AWSLambdaFullAccess and arn:aws:iam::aws:policy/AmazonDynamoDBFullAccess

Please refer to following diagram.

Using the AWS console create the Lambda fuction lambda-proxy-api.

• Runtime Java 8
• Handler io.lambda.proxy.lambda.LambdaFunctionHandler
• Existing Role lambda_basic_execution

Please refer to following diagram.

Using the Gradle wrapper build a deployable archive of the Lambda function.

$ /{PROJECT_HOME}/lambda-proxy-service/lambda/lambda-proxy-api/./gradlew clean build -x test --refresh-dependencies

{PROJECT_HOME}\lambda-proxy-service\lambda\lambda-proxy-api>gradlew clean build -x test --refresh-dependencies

Deployable archive payload.zip will be created in the following location /{PROJECT_HOME}/lambda-proxy-service/lambda/lambda-proxy-api/build/distributions

D:\workspace\lambda-proxy-service\lambda\lambda-proxy-api>aws lambda update-function-code --function-name lambda-proxy-a
pi --zip-file fileb://build/distributions/payload-1.0.0.zip

Using the AWS console create a DynomoDB table Employee with Hash Key id, with secondary index for type

Following diagram shows the Employee table design