API Gateway, Zuul

https://www.youtube.com/watch?v=1vjOv_f9L8I

An API gateway is a vital component in any microservice architecture. - An Edge Service
1 Microservice acts as a Gateway for rest of microservices

API Gateway is an abstraction layer - a FACADE

If We have microservices URL and those URLs are directly used by Client UI Developers

it would create issues later if we would like to change them in future.

So, We can have a FACADE Layer which would abstract real URLS

This can be achieved by Using API Gateway - A kind of Edge Service

Netflix has an open source library for this purpose called "Zuul"

API Composition - Making 1 Microservice out of many other

Single Point of Entry

Monitoring System for Requests/Responses

External Contract  ----------> Zuul Gateway ------> Internal Rest API

 

Advantages

• Monitoring 
• Authentication

Disadvantages & Mitigation Steps

• Little bit Slow - 1 Additional Network Hop 
• Single Point of Failure - You need to have multiple redundant Zuul Gateway  to overcome it
• Backend for Frontend - Different Backend for Android, Apple, Web - Layers - Different API Gateway for Different Types of Frontend

Works on Filter Based Design Pattern
PreFilter
PostFilter
etc