API Gateway Pattern
Imagine you're building an e-commerce application using microservices. Your system has several independent services:
- User Service: Manages user accounts and profiles.
- Product Service: Handles product listings and inventory.
- Order Service: Manages customer orders.
- Payment Service: Processes payments.
- Notification Service: Sends emails and push notifications.
Now consider what happens when a customer opens your application. The frontend needs to communicate with multiple services to fetch product details, retrieve orders, and manage the user's account.
One approach is to let the frontend communicate directly with each microservice. For example:
This might work for a small application, but it creates several challenges as the system grows. The client needs to know where every service is located. If a service changes its address or API structure, the client might need to be updated.
Each microservice must also handle common concerns such as authentication, rate limiting, and request logging. And if the frontend needs data from multiple services, it may have to make several network requests.
The API Gateway Pattern addresses these problems by introducing a single entry point between clients and backend microservices.