https://hackernoon.com/build-a-realtime-serverless-graphql-api-with-websockets-on-aws-d9e553a997

With the release of AWS AppSync we finally have the ability to create realtime serverless apps on AWS. Previously you were forced to spin up EC2 instances in order to create websocket connections as they are not supported by AWS Lambda.

In the tutorial you’ll learn how to build a simple GraphQL API using AWS AppSync. Then you’ll write a client app in vanilla javascript (no frameworks) that receives realtime updates via websockets. Let’s get started!