Serverless eliminates the need to plan for infrastructure and let's you focus on your application.

Following are optimization katas you should be aware of while building a serverless applications

• The Lean function
  • Concise logic - Use functions to transform, not transport (utilize some of the integration available from the provider to transport), and make sure you read only what you need
  • Efficient/single purpose code - avoid conditional/routing logic and break down into individual functions, avoid "fat"/monolithic functions and control the dependencies in the function deployment package to reduce the load time for your function
  • ephemeral environment - Utilize container start for expensive initializations
• Eventful Invocations
  • Succinct payloads - Scrutinize the event as much as possible, and watch for payload constraints (async - 128K)
  • resilient routing - Understand retry policies and leverage dead letter queues (SQS or SNS for replays) and remember retries count as invocations
  • concurrent execution - lambda thinks of it's scale in terms of concurrency and its not request based/duration based. Lambda will spin up the number of instances based on the request.
• Coordinated calls
  • Decoupled via APIs - best practice to setup your application is to have API's as contracts that ensures separation of concerns
  • scale-matched downstream - make sure when Lambda is calling downstream components, you are matching scale configuration to it (by specifying max concurrency based on downstream services)
  • secured - Always ask a question, do I need a VPC?
• Serviceful operations
  • Automated - use automated tools to manage and maintain the stack
  • monitored applications - use monitoring services to get holistic view of your serverless applications

Whether to reduce your infrastructure costs, shrink the time you spend on ops tasks, simplify your deployment processes, reach infinite scalability, serverless cuts time to market in half.

Serverless computing is a cloud computing execution model in which the cloud provider dynamically manages the allocation of machine resources. Pricing is based on the actual amount of resources consumed by an application, rather than on pre-purchased units of capacity.

Serverless is a toolkit for deploying and operating serverless architectures.

The term ‘Serverless’ is confusing since with such applications there are both server hardware and server processes running somewhere, but the difference to normal approaches is that the organization building and supporting a ‘Serverless’ application is not looking after the hardware or the processes - they are outsourcing this to a vendor.

Some of the Serverless Cloud Providers are

...

Anything that triggers an Lambda Function to execute is regarded by the Framework as an Event. Most of the Serverless Cloud Providers support following Events

• Http
• PubSub Events
• scheduled

AWS supports processing event generated from AWS Services (S3/Cloudwatch/etc) and using aws as a compute engine is our first choice.

This example creates a backend for ‘persons’ collection which uses DynamoDB NoSQL database service also provided by Amazon.

AWS Lambda SDK provides pre-defined interface com.amazonaws.services.lambda.runtime .RequestHandler to implement our lambda function.

public class LambdaInfoApiHandler implements RequestHandler<Map<String, Object>, ApiGatewayResponse> {

  private static final Logger LOG = Logger.getLogger(LambdaInfoApiHandler.class);
  private static final Integer SUCCESS_STATUS_CODE = 200;


  @Override
  public ApiGatewayResponse handleRequest(Map<String, Object> input, Context context) {
    
  }
}

handleRequest method is where the function code is implemented. Context provides useful information about Lambda execution environment. AWS Lambda function needs a deployment package. This package is either a .zip or .jar file that contains all the dependencies of the function.

serverless.yml contains configuration to manage deployments for your functions.

• Node.js v6.5.0 or later.
• Serverless CLI v1.9.0 or later. You can run npm install -g serverless to install it.
• An AWS account. If you don't already have one, you can sign up for a free trial that includes 1 million free Lambda requests per month.
• Set-up your Provider Credentials. Watch the video on setting up credentials

• cd serverless
• mvn clean package
• serverless deploy --stage=dev --verbose

Based on the configuration in serverless.yml serverless framework creates following resources

• CloudFormation stack for S3 (ServerlessDeploymentBucket)
• IAM Role (IamRoleLambdaExecution)
• CloudWatch (log groups)
• API Gateway (ApiGatewayRestApi)
• Lambda function
• DynamoDB collection

The command will print out Stack Outputs which looks something like this

endpoints:
  GET - https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/info
  POST - https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person
  GET - https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person/{id}
  

CurrentTimeLambdaFunctionQualifiedArn: arn:aws:lambda:us-east-1:xxxxxxxxxxx:function:lambda-info-http-endpoint-dev-currentTime:4
ServiceEndpoint: https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev
ServerlessDeploymentBucketName: lambda-info-http-endpoin-serverlessdeploymentbuck-2u8uz2i7cap2

access the endpoint to invoke the function.

Use the following cURL commands to test the endpoints

curl -X GET \
  https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/info \
  -H 'cache-control: no-cache'

curl -X POST \
  https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person \
  -H 'cache-control: no-cache' \
  -H 'content-type: application/json' \
  -d '{
	"firstName": "Thor",
	"lastName": "Odinson",
	"address": {
		"addressLineOne": "1 Odin ln",
		"addressLineTwo": "100",
		"city": "Asgard",
		"state": "country of the Gods",
		"zipCode": "00001"
	}
}'

curl -X GET \
  https://xxxxxxxxx.execute-api.us-east-1.amazonaws.com/dev/api/person/{id} \
  -H 'cache-control: no-cache'

• serverless docs
• Serverless Architectures
• Serverless Black Belt