API Gateway Communication

API Gateway is the front-door for outside users. API Gateway contain all the routing rules which developer setup before. The http-request coming which from outside is passed into specific request-handler according to routing rule. Then http-payload is transform into event-payload inside the request-handler according to request-mapping rules. Finally API Gateway send the event to event-bus , All the functions whose listening for that event, able to get the message. Then process it.