Mastering Microservice Patterns: Unlocking the Power of the API Gateway

Introduction

This article explains the API Gateway Pattern, its necessity, benefits, and drawbacks. We will also present examples of a microservice application without and with this pattern.

Microservice application Without API Gateway Pattern?

• Clients Apps (Web, Mobile,...) access backend services directly.
• When client apps need data from multiple services, the aggregation of this data will be done in clients apps.
• Authorization, Authentication, rate limit, SSL certificate and load balancing must be handled in each service.
• Every service must expose a public URL to be accessed by client apps.
• Client apps need to handle different protocols like gRPC, restful APIs.

And this makes client Apps and backend services are tightly coupled, make client?apps have a complex logic and make the deployment is complex so that we need API Gateway Pattern to solve these drawbacks.?

Microservice application With API Gateway Pattern?

• Client?apps access backend services through Gateway service using a single protocol and Gateway takes the job of handling different protocols between it and other services.
• When a client app needs data from multiple services, just access Gateway through a single API and Gateway access service and aggregate data and send it back to the client.
• Authorization, Authentication, rate limit, SSL certificate and load balancing are handled in gateway only.

Another Variation for API Gateway Pattern?by making gateway for each client App

• this reduce the complexity of Gateway

Benefits of using API Gateway Pattern?

• Protocol transformation: the gateway is responsible for handling different protocols in service and exposing APIs for clients in restful APIs.
• Caching: the responses can be cached in gateway to reduce latency.
• Simplified Access: Clients have a single point of access to backend services.
• Security: Authorization and Authentication are centralized in the gateway.
• Monitoring, logging: tracing for requests to access microservices are handled in the gateway.

Drawbacks of using API Gateway Pattern?

• When using Gateway as a single entry point to backend services this makes it a single point of failure, so the gateway must be highly available.
• Increase latency for clients due to extra service between clients and backend services.
• Gateway may be a bottleneck for application if it is not scaled.
• Extra service is added to the application and this increases complexity.

Conclusion?

The decision to use the API Gateway Pattern depends on the specific needs of your application. If your application has a small number of services, you might opt to avoid this pattern to simplify the architecture. However, for applications with a large number of microservices, the complexity of direct client access can outweigh the simplicity of using an API Gateway, making it a beneficial choice.