An API Gateway is the programming element that orchestrates and coordinates how various requests are processed in a microservice architecture. It sits at the front of the API and acts as a single entry point into a system allowing multiple APIs to function cohesively and offer a smooth experience to the user. Typically, an API Gateway handles a request by invoking several microservices and aggregating the results to identify the best path. And since a gateway is responsible for protocol translations, using an API kind of front-end programming is vitally essential for computer applications (clients) that are built with microservices that utilize multiple, disparate APIs.
An API Gateway features an HTTP server where routes are associated with a FaaS function or a microservice. When the API Gateway receives a request, it checks up to see which services are needed and combines them to form a synchronous experience for the user. It maps the request’s parameters to the input arguments of the service or function, to establish a high starting point. The most critical role of the API Gateway is to facilitate reliable processing of all API calls. Additionally, it also helps to provide enterprise-grade security, design API specs, and manage APIs centrally.
Since developers are required to update the API Gateway when a new microservice is added or removed, it is vitally essential for the updating process to be as lightweight as possible. Therefore, when evaluating API gateways, developers should consider which outstanding features that have been added by the vendor to differentiate their product from the rest.
Additional Tasks are implemented on the API Gateway
Besides the routing task, an API gateway also allows the implementation of other tasks such as:
1. Load Balancing
Load balancing is a technique that is designed to distribute workloads uniformly to optimize work efficiency and maximize network capacity. An API Gateway keeps track of all requests and attains a perfect balance when loading them to different nodes of a particular service.
An API Gateway can also help authenticate API calls from outside, thereby help to improve security and lower the network latency.
3. Request Dispatching and Service Discovery
By receiving calls and waiting for results from all services, a gateway can combine results and send them back to the client, thereby simplifying the communication process between the client and a microservice. Additionally, it can determine the necessary response time for all requests, and route the priority API calls to the most expedited responding node.
4. Acting as a Circuit Breaker
An API Gateway can also aid in rectifying a partial failure through what is referred to as circuit breaker pattern. This is when the gateway curtails data transfer to a failing component when a specific threshold has been reached. This gives developers enough time to evaluate the logs, fix the hitch, or update the components.
5. Facilitating Cache Management
Cache management is another common API Gateway feature. Typically, an API Gateway will allow you to configure cache settings to improve API performance and reduce the traffic it sends to your back end. Learn more about caches and how they pertain to APIs.
Why Use an API Gateway?
The most significant benefit of using API gateways is that they permit developers to encapsulate the internal structure in several ways. Besides accommodating requests, gateways can be utilized to call multiple back-end services and aggregate the results. Developers can also use API gateways for the following reasons:
- They enhance the security of your microservices
- They facilitate the support for combining communication protocols.
- They help mock or virtualize services to assist in integration testing or validate design requirements.
- To decrease microservice complexities and maintain focus on the core tasks at hand.
API Gateway Example
A perfect example of an API Gateway is the Netflix API. Because the Netflix streaming service is available on a diverse range of devices including smartphones, blue-ray players, and televisions, their attempt to use a one-size-fits-all API style proved futile. Therefore, they had to use an API Gateway that implements a separate API for every device.