This is the Reference architecture for RESTful microservices.

1- Clients send request our microservices by making HTTP API calls.

Ideally, our clients should have a tightly bounded service contract to our API

in order to achieve consistent expectations of microservice responsibility.

2- Amazon API Gateway hosts RESTful HTTP requests and responses to customers. In this scenario, API Gateway provides built-in authorization, throttling, security, fault tolerance, request/response mapping, and performance optimizations.

3- AWS Lambda contains the business logic to process incoming API calls and leverage DynamoDB as a persistent storage.

4- Amazon DynamoDB persistently stores microservices data and scales based on demand. Since microservices are often designed to do one thing well, a schemaless NoSQL data store is regularly incorporated.

https://medium.com/aws-serverless-microservices-with-patterns-best/building-restful-microservices-with-aws-lambda-api-gateway-and-dynamodb-614209bcad7