The simplest way to answer “what is an API gateway?” is that it’s a traffic manager for data that applies policies, authentication, and general access control to keep data secure. An API gateway gives you control-access over your back-end systems and optimizes communication between external clients and backend services. API gateways ensure the scalability and availability of your services by routing requests and responses to and from the appropriate services. API gateways maintain a secure connection between data and APIs while managing API traffic and requests.
Much the same way phone line operators once received a call and then connected it accordingly, an API gateway receives API calls from consumers and directs them to the correct microservices using request routing, composition, and protocol translation. One of the most common reasons API gateways are useful is because they can route to multiple back-end services and aggregate results. This is an effective alternative to the one-size-fits-all API and results in a better user experience.
API gateways are designed with security in mind from the ground up. There are several key functions that an API gateway can perform. An API gateway serves as an inline proxy point of control over APIs, verifies the identity of API requests, regulates which traffic is authorized to access backend services, meter the flow of traffic, log all transactions and enforce governance, and provides an extra layer of security for backend services that power APIs.
An API gateway authenticates API calls so that they are authenticated once at the gate before being routed to potentially multiple services. Authentication reduces latency and ensures consistent processes across the application. API gateways can call out to other systems to verify the identity of requestors and assess the risk level of any incoming API consumers. The risk-assessment of an incoming API can be delegated to a third-party application if necessary.
The more that microservices are used, the more valuable API gateways are becoming. Microservices allow for the deconstruction of an application into coupled services, making it easier to develop, deploy, and maintain different functions within an application. The trouble with microservices is that they make it challenging for customers to quickly and securely access the application. API gateways solve this issue by serving as a single entry point for requests. This is essential to businesses that experience high call traffic from mobile applications such as Uber or backend application Google Maps.
Making microservices accessible through an API gateway means faster, simpler, more secure access to your services. Digital business models can benefit greatly from implementing API gateways. Presenting APIs and backend systems in a single interface offers better security, results in simpler code writing, decreased latency, faster access to microservices, a decrease in workload or load balancing, and a comprehensive collection of metrics. Using an API gateway is a smart way to conceal how your application is partitioned from the requestor because they no longer need to know the locations of individual services.
It’s far easier and faster to test and release new versions of an API when you can run them simultaneously using an API gateway. Requestors experience the lowest possible latency for API requests while backend services are load-balanced to withstand traffic spikes.
API gateways are commonly used in modern architectures to manage API requests, aggregate responses, and enforce service level agreements. They’re also essential to protecting APIs by providing an additional layer of security to access points. The more that APIs are connected with the digital ecosystem of applications, developers, partners, and customer experiences, the more valuable they become.