All You Need to Know About API Gateways

API Gateways Deliver Fast, Easy Access to Cloud-Based Applications

What is an API gateway? API stands for Application Programming Interface, and it's a type of software used for cloud-based application access. It takes a user's access request, directs it to the applicable back-end service(s), gathers necessary data, and then combines everything into one package. An API gateway also adds threat protection and even analytics.

The Benefits of Using an API Gateway

With an API gateway, applications have a single entry point regardless of whether it is hosted on the cloud or on-premises, which minimizes workload. It handles all requests originating from remote users and then sends back the needed data.

To illustrate practical usage, a restaurant may have a web application that customers can access via laptops and mobile devices. This allows users to put in a single request and then access and peruse the menu, reviews, pictures, the payment service, and directions. This information comes from a range of back-end services but comes to the user in one place thanks to the API gateway.

Other benefits of using an API gateway include making data available to suit the technology employed by the user. A customer looking at a retail store's site on a web browser will see a different format and more information than one using the same store's mobile app.

API gateways also facilitate real-time communication between cloud-based data services on the front and back end. This supports various web chat, gaming, and stock trading applications.

The Relationship to Edge Microservices

API gateways are sometimes also referred to as 'edge microservices.' They are commonly used in applications developed with modern, cloud-native microservices architecture. These applications often have several facets that have a single function and work independently. A dedicated DevOps team even manages each one. Though the microservices work toward a common end, they have their own specified databases and can be tested and maintained discretely from each other.

Information requests sent to an application with microservices go through a streamlined process handled by the API gateway. This makes it secure, fast, and dependable, even within vast and complex applications.

Any changes made to individual microservices won't affect the other microservices. This allows for scalability and the faster development of new features and upgrades.

Monolithic Apps, Precursor to Microservices

Monolithic applications were the original option before the innovation of microservices. They fit into a framework of all-in-one architecture and are connected to a single database. All components in a monolithic app are interdependent and function as a unit. Changing one means changing all aspects of the application.

Monolithic applications are still in use today, and they use API gateways to interact with third parties, internal users, and approved vendors. They still offer the security and scalability associated with microservices.

How API Gateways Function

You know what purpose they serve, but how do API gateways work, exactly? Acting as an intermediary between microservices and the end-user, they serve three crucial functions:

  • Routing: With each new incoming request, API gateway routing creates multiple requests and then uses a routing map to send the different requests to the correct microservice.
  • Composition: The API gateway gathers the information returned from the microservices in response to the user's request, puts it together, and then sends it back to the user.
  • Translating Protocols: Users send requests via different devices, and API gateways take this into account. They translate the different protocols of these devices, allowing communication between the device and the microservices. Even a WAN (wide area network) and a LAN (local area network) use different protocols and have their own unique requirements. For example, if the client device sent a request using JSON but the microservice returns responses in XML, the API translates in both directions.

What Using API Gateways Does for Your Enterprise

Utilizing API gateways for your microservice applications offers a variety of benefits:

  • Additional security: An API gateway improves security at the back end and prevents exposure of an application's endpoints. Using HTTPS or HTTP protocol and SSL encryption also enhances security and overall performance.
  • Authenticating Users: API gateways help ensure that requests come from legitimate users and not from malicious sources such as hackers. Token-based authentication in web API and other methods prevent viruses and other malware infiltration.
  • Ensuring Correct Requests: Input validation verifies that an API request has all the required information in the correct format before being handed off to a microservice. Requests with missing or incorrect information are rejected.
  • Shorter Response Times: With an API gateway sending requests directly to the right services, traffic and latency are reduced. This means the user gets a response more quickly and has a more positive experience.
  • Load Balancing in Microservices: An API gateway tracks the requests sent to different microservices and balances the load between nodes. This helps to ensure efficiency and application availability, even during high traffic periods where spikes or DOS events may occur.
  • Managing Workloads: With rate limiting, an API gateway monitors traffic levels and limits the number of requests from a single client in a set time. This helps keep workloads manageable and prevents malicious actors from overloading the system.
  • Simplified Billing: One way for businesses to add to their revenue stream is to monetize aspects of their APIs by offering different paid services or products. The API gateway also sends pricing information for these products and services to a billing system where users can make their payments when it handles traffic. Other APIs send revenue to users as part of affiliate marketing or ad revenue share arrangements.
  • Optimization: API gateways can help to optimize API calls with microservices caching. This practice allows cached responses to be stored and used repeatedly as similar requests come in. This decreases cost and improves performance and responsiveness.
  • Accurate Analytics: It is easy to keep track of trends over time with an API gateway since it's already controlling and monitoring inbound traffic. This helps enterprises stay ahead of the curve and detect potential infrastructure problems.
  • Compatibility with Legacy Apps: Many businesses still use older legacy applications that provide crucial services, though these apps were not originally developed to work with API gateways. Tools such as throttling and rate-limiting help manage the requests from these applications without undergoing a time-consuming cloud migration.

Other Considerations When Using API Gateways

While adding an API gateway has many benefits, some challenges arise that need to be considered:

  • Latency: Despite the reduced response time and greater efficiency of using an API, the very process of a request having to pass through an API gateway may increase response time.
  • Microservice Dependency: Any change to microservices also requires an API gateway update to ensure continued smooth performance. Putting design rules in place helps to mitigate this.
  • System Complexity: While an API gateway helps streamline many processes, it is still another system that requires maintenance, attention, and resources. Routing logic may also increase the complexity of communication with microservices.
  • Safety and Security: Security is paramount since an API gateway interacts with multiple parts of your enterprise. A compromised API can have a serious impact on your network and data.
  • Dependable Redundancy: One thing to remember is that if only one API gateway is running, that gateway's failure means the failure of the entire application and not just one facet of the application. Having multiple API gateways and load balancers helps to ensure redundancy.

Using an Open-Source API Gateway

Open-source API gateways save DevOps teams the time and effort of writing code to create alternative sources. Open-sourced gateways are readily available so a new enterprise can get started and scale up quickly as needed.

Using API Gateways and Service Mesh

Service mesh is a part of an app's infrastructure which tracks how different services interact. This helps to optimize communication so that microservices can work more efficiently. Service mesh works on most platforms and architectures to help make almost any system work faster.

>API Gateways and Kubernetes Services

An ingress is a specific object that sets parameters for accessing Kubernetes services from outside a Kubernetes cluster. It also provides load balancing, virtual hosting, and SSL termination. DevOps teams can use it to merge routing. A drawback of Ingress is that it does not have a lot of the same features as API gateways. It doesn't offer authentication, rate-limiting, or security as API does.

API Management vs. API Gateways

If you see the term API management, it is not the same thing as an API gateway. API gateway handles and routes requests, while API management is a broader function that oversees the entire API lifecycle, including the gateway.

The API lifecycle comprises three primary phases. These are the creation of the API, controlling and maintaining security, and consuming via publishing or monetization. API gateways are part of the control phase of the lifecycle.

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