What Are API Gateways and How Do They Work?

Learn how API gateways are assisting businesses in providing faster, simpler, and more secure access to cloud-based data and services.

An API gateway is software that accepts an application user’s request, directs it to one or more backend services, gathers the necessary data, and presents it to the user in a single, integrated package. It also delivers analytics, threat defense layers, and other application security.

The value of an API gateway

Whether the app is hosted in an on-premises data center or the cloud, an API gateway offers a single entry point for all API calls that come into it. It receives remote queries and responds with the needed information.

Consider the web application for a restaurant. Despite all of the information being gathered and sent from separate backend microservices or APIs, a user may input one request and simply access the restaurant’s menu, diners’ photographs and reviews, payment service, and a map to check its location using a laptop or mobile. An API gateway receives and processes their request.

Aside from handling requests, an API gateway adds value by making data available in a format that is compatible with the requestor’s technology. When someone uses a web browser to seek information about a retail store, for example, they are given far more information than when they use a mobile phone to request and view the same store’s data. API gateways can also provide real-time communication between the frontend and backend of an application, such as in web chat, stock trading platforms, and online gaming.

API gateways and microservices

API gateways, often known as “edge microservices,” are commonly utilized in current, cloud-native microservices architecture systems. Many separate, autonomous, single-function components (or microservices) make up these apps, each controlled by its own small, self-contained DevOps team. The microservices are loosely connected, connect to their databases, and can be independently deployed, managed, and tested.

An API gateway provides a simplified manner for receiving and returning data when requests for information come into an application using microservices. It can handle access control as well as transmit data quickly and reliably in big and complicated applications.

Microservices may be introduced, updated, relocated, and modified without affecting the larger program since they run in their separate contexts. API gateways let businesses grow their apps more easily. They can also build new features more quickly, enabling more innovation and a shorter time to market.

API gateways and monolithic apps

There were monolithic apps before there were microservices. These apps rely on services from an all-in-one architecture that is linked to a single database. All of the components are interdependent and work together as a single entity. Changing any part of a monolithic program necessitates rewriting the whole architecture’s code.

There are still a lot of monolithic programs out there. They generally employ API gateways to interact with external third parties, internal users, or partners, while maintaining the same security, scalability, and other advantages that microservices provide.

How do API gateways work?

API gateways provide three main services between a user and a set of microservices:

1. Request routing: When an API gateway gets a new API request, it splits it into many requests, checks a routing map to determine where each request should go, and delivers the requests to the appropriate internal microservice or microservices.

2. API composition: The API gateway composes workflows by aggregating information from several microservices, bundling it, and returning it to the requestor in a composite form.

3. Protocol translation: API gateways recognize that API requests are sent from devices that utilize various API protocols, and they translate those protocols so that client requests and microservices may connect. The gateway converts API protocols from the end-user device’s protocol to the microservice’s protocol, whether it’s a web browser, mobile device, or another endpoint. For example, a wide area network (WAN) and a local area network (LAN) behave differently and require distinct APIs. When information is returned, the gateway modifies it and transmits it to the requestors in a manner that they can understand. If a microservice responds in XML but the request is submitted in JSON, the gateway will automatically translate the response. The HTTP protocol is used by a REST API to request API services.

Benefits of API gateways

Including one or more API gateways in your microservice applications has some advantages:

• Microservices Security: An API gateway acts as a barrier between an application’s backend and the outside world, making it more secure. It implies that an application’s endpoints aren’t exposed, reducing the risk of an attack. For further protection, a corporation might utilize HTTPS or HTTPS encrypted with SSL, which increases efficiency.
• API authentication: By authenticating API calls, an API gateway adds another degree of protection to defend against errors, attacks, and data breaches. Antivirus scanning, decryption and encryption, token translation, validation, and other security operations can all be part of authentication and authorization.
• Input validation: Before an API request is passed on to a microservice, input validation ensures that it has all of the necessary information in the right format. The gateway rejects the request if anything is missing or incorrect. The gateway sends the request once it has been confirmed as correct.
• Faster response time: Because an API gateway sends requests directly to the appropriate services, there are fewer roundtrips and traffic, as well as lower latency and higher overall performance, resulting in a better user experience.
• Microservices load balancing: An API gateway maintains track of requests submitted to various microservices, balances load between nodes for efficiency, and guarantees that the application is online. When significant traffic volumes are predicted, such as during a Black Friday sale or a new product launch, load balancing is crucial to avoid spikes or denial-of-service incidents.
• Rate limiting: To prevent the system from being overloaded with requests and perhaps failing, an API gateway monitors traffic coming in from all sources and restricts how many API calls a client (or malicious bot) may make in a certain time – per second, per day, week, or month — to protect the system from being flooded with requests and possibly crashing.
• Billing for microservices: Some firms monetize their APIs by providing a service to customers or other businesses. The API gateway manages traffic, tracks consumption for certain goods or services, and transmits price data to a billing system that is linked. Direct monetization can take several forms, including customers paying as they use a service or resource, for a certain amount of services, or via tiers (where different services are provided at different levels). Other APIs distribute income to customers through ad revenue sharing, affiliate marketing, or bill credits.
• Microservice caching: API gateways, such as microservices caching, can assist optimize API requests. Backend services can be relieved of unnecessary load by caching API answers. When comparable requests are received, the cached results can be utilized, boosting performance and lowering costs.
• Monitoring and tracking apps’ analytics: Because an API gateway manages all of an application’s incoming traffic, it’s simple to have the software track and report on API use visibility, trends, and other information. The gateway software can also provide traffic logs, which can assist an API provider in identifying and correcting infrastructure issues.
• Extending legacy apps: Businesses continue to employ legacy programs that hold critical data, perform important services, and add value, but they were not designed to work with APIs. Older technology may struggle to handle the growing volume of calls coming in from newer technologies like mobile, SaaS, and IoT apps. They might also be difficult to locate. Instead of undertaking a difficult cloud transfer, a DevOps team may update and expand the capability of a legacy application by adding API functionality, which includes features such as rate limitation and throttling.

Challenges of API gateways

While there are several advantages to using an API gateway, there are also some disadvantages:

• Response time: While queries traveling more efficiently reduce the delay and response time, the additional step of passing via an API gateway might increase response time.
• Dependencies: Any time a company adds, alters, or removes a microservice, the API gateway must be updated. With an application that has grown from a few to a large number of microservices, this can be difficult. Creating API design rules, on the other hand, can help with this.
• Complexity: Routing logic can make microservice communication more difficult. Another system that must be designed, implemented, and maintained is the API gateway.
• Security: Because an API gateway interacts with so many aspects of an organization’s systems, its failure can have a significant influence on the security of an application.
• Reliability: If there is only one API gateway and it goes down, the entire program goes down. Using load balancers and several API gateways can assist avoid this problem.

Open-source API gateways

DevOps teams may use an open-source API gateway to add new API sources without having to write code. An open-source API gateway has several advantages, including the ability to start small and scale up rapidly, the ability to develop and adapt quickly, and the ability to provide transparency to users.

API gateways with service mesh

Service mesh is an infrastructure layer that offers a consistent mechanism for services to interact inside a system. It may be utilized with microservices architecture and on any platform, including VMs, containers, Kubernetes, Docker, or serverless applications. Using an API gateway in conjunction with a service mesh improves API security and delivery speed.

API gateways and ingress

Ingress is a Kubernetes object that defines the rules for accessing Kubernetes services from outside the cluster. It enables a DevOps team to combine routing and load balancing into a single resource, as well as SSL termination and name-based virtual hosting.

It does not, however, provide some of the other API gateway capabilities, such as authentication, security, rate restriction, and so on. API gateways have greater configuration, security, and flexibility than ingress.

What is the difference between API management and API gateways?

While an API gateway stands in front of APIs, managing, routing, and securing API requests, API management encompasses the complete API lifecycle and includes API gateways. Another way of looking at API gateways is as API administration tools.

The API lifetime is divided into three phases: producing (developing and documenting the API), controlling (implementing security), and consuming (publishing and monetizing your APIs). API gateways are part of the control phase of the API lifecycle, and they protect APIs and data.

API gateways and IBM

APIs will continue to represent a small portion of your organization’s application modernization and transformation.

When it comes to addressing such needs, more automation would be beneficial. In an ideal world, it would begin with simple, measurable initiatives that you could then expand and improve for additional processes and portions of your company.

Working with IBM gives you access to AI-powered automation solutions, such as prebuilt workflows, that may help you speed innovation by making every process smarter.

Take the next step:

• Create, securely expose, manage, and monetize APIs across cloud computing platforms with IBM API Connect®, a straightforward and scalable API design platform.
• In the Solution Developer: IBM API Connect program, you’ll learn how to construct developer communities, publish and distribute APIs, and interact with them through a self-service portal.
• API Connect may also be used in conjunction with other automation features in IBM Cloud Pak® for Integration, a hybrid integration solution that offers a fully automated and closed-loop lifecycle for a variety of corporate integration types.
• Explore the IBM Sterling Supply Chain Business Network B2B API Gateway for safe connections between you, your clients, and your partners for Business to Business API connections.
• Take our integration maturity assessment to measure your degree of integration maturity across crucial dimensions and see what steps you can take to get to the next level.
• Download our agile integration guide to learn more about the benefits of integrating solutions using a container-based, decentralized, microservices-aligned strategy.

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