Introduction to the API Gateway Pattern

A phone app opens its home screen. To draw that one screen it needs the user profile, a list of recommendations, the unread notification count and the current subscription state. In a microservices system those four things live in four services, on four addresses, each with its own error format.

Without help, the app has to know all four addresses, call each one, and handle each one's failures. Add a fifth service and every client has to be changed.

What is the API Gateway Pattern? It puts one service in front of all the others. Clients send every request to that one address