APIs are often referred to as the front door for applications to access data and business logic from back-end services. An API is essentially an interface that a software provides to other people or programs that allows them to interact with that software.
When creating an API, you need to choose a programming language (j**a, python, php, etc.) to write the API logic, you also need to deploy the API to the server, and monitor the API to ensure that the infrastructure has enough capacity to handle the large number of requests.
API Gateway abstracts these steps away and you don't need to write too much and don't worry about managing the underlying infrastructure, you just need to create API endpoints where clients can send requests.
The major cloud providers offer fully managed API gateway services:
AWS API Gateway.
GCP API Gateway.
Azure API Management.
This article will explain why you should use API gateways, how they work, and we'll look at API gateway examples in real-world applications.
What we'll cover::
1.Why use an API gateway?
2.How API Gateway works.
2.1 Request verification.
2.2 Authorization and Certification.
2.3 Rate Limiting.
2.4 Request Routing.
2.5 Request and Response Translation.
3.Real-world examples.
API Gateway is a fully managed service that makes it easier for developers to create, publish, maintain, monitor, and secure APIs at virtually any scale.
In a cloud computing environment, "fully managed" means that responsibility for the maintenance and management of services rests with the cloud provider, which means that the underlying infrastructure, software updates, security, scalability, availability, and disaster recovery are all managed by the cloud provider.
This abstraction mainly makes the developer's job easier, as they only need to focus on developing the service and don't have to worry about managing it.
In this case, this abstraction comes at the cost of a loss of flexibility, with most cloud providers offering API gateways with a hard limit on the number of requests per second (RPS) processed.
The cost of using managed services such as API Gateway is also higher and must be weighed against the higher number of developer days (number of developers * working days) required to build an API from scratch.
To truly understand the benefits of using API Gateway, let's take a look at the steps you need to follow to design, write, and deploy traditional APIs:
Step 1: Define the requirements and scope
Understand the needs of your target users or systems.
Determine the data and functionality that the API will expose.
Step 2: Design the API
Define API endpoints and methods (get, post, put, delete).
Design the request and response format (typically JSON or XML).
Specify the data model and resources that the API will interact with.
Plan Error Handling and Status**.
Step 3: Develop the API
Select a programming language and framework.
Implement the API endpoints defined during the design phase.
Integrate with databases or other services as needed.
Ensure that security practices, such as input validation and rate limiting, are implemented.
Step 4: Deploy the API
Choose a hosting solution (cloud provider, on-site server).
Set up the deployment environment.
Deploy the API to the server.
Step 5: Monitor and maintain the API
Monitor APIs for uptime, performance, and errors.
Regularly update the API to fix bugs and patch security vulnerabilities.
With API Gateway, you mainly need to focus on steps 1, 2, and 3, and the other steps are mostly abstracted out and handled by the API Gateway.
The main reason to use an API gateway is to simplify the process of developing and maintaining APIs.
API gateways do a lot of things at the same time.
To understand how an API gateway works, let's use an analogy.
API gateways are like ma tre d' (French, meaning maîch waiter), ma tre d' is usually found in high-end restaurants, although it is a profession that is slowly disappearing.
The maître d'affaire is the liaison between the guests and the restaurant staff and is responsible for:
Greetings and seat assignments: The maître d'être d'n' is usually the first person a guest encounters when they arrive at the restaurant. They warmly welcome guests, ask about reservations, and assist guests with seating, taking into account preferences and special requests.
Reservations: The foreman is responsible for managing bookings and ensuring that tables are allocated efficiently. They keep track of available tables and booking times, making the necessary adjustments to meet the needs of their guests.
Manage wait times: During busy periods, the foreman manages the waiting time of guests by providing estimated waiting times and offering alternatives, such as seating guests at the bar or waiting area.
Problem solvingIf any problems or concerns arise during the meal, the foreman should intervene and solve the problem in a timely manner to ensure the satisfaction of the guest.
Handle special requestsIf a guest has special requests or dietary restrictions, the maître d'être d'être will communicate this information to the kitchen and ensure that the guest's needs are met.
In short, a maître d'être d'être de la maître d'être de l'ð (d'être) is a person in a restaurant with multiple talents and responsibilities, and from the following **, we can see how the maître d'être d'être ù is a communicator with the
An API gateway works in a similar way, acting as a communicator between a client and many of the services it may need to access.
Let's look at what an API gateway can do in more detail.
This includes checking incoming requests to confirm that they meet predefined criteria before reaching the backend service.
This may include checking the structure of the request, validating the data type, ensuring that the required parameters are present, and validating the query parameters, headers, and request body against the schema.
By doing so, the API gateway acts as the first line of defense, preventing non-standard or malicious requests from reaching the backend system.
To use a restaurant metaphor, this is similar to a maître d'æ waiting at the door of a restaurant to greet guests, but remember, this is an upscale restaurant, so the maître d'être d'ny makes sure that the guests are dressed in accordance with the restaurant's dress code – similar to validating an incoming API request against a predefined pattern.
Authentication is the process of verifying the identity of the user or service making the request, typically through credentials such as a username and password, token, or API key.
Once authenticated, authorization determines which resources or actions the authenticated entity has access to or perform.
API gateways are typically integrated with identity providers and support various authentication and authorization mechanisms, such as OAuth, JWT, API keys, and more. They ensure that only legitimate, authorized requests pass through the backend service.
Authentication focuses on "who", while authorization focuses on "permissions".
For the foreman who greets guests into a restaurant, identity verification involves the guest proving that they are who they say they are, usually by presenting some form of identification with a ** that matches their face.
Authorization will involve checking if they have a reservation, which means they have the right to enter the restaurant to order.
Rate limiting involves controlling the number of requests a user or service can make within a specified time frame, and is typically defined as a limit on the number of requests per second (rps).
Rate limiting helps avoid overloading backend services and ensures that they are still available. Rate limiting is also used as part of your cost control strategy, as you'll be charged for each request you send to the API gateway.
API Gateway can enforce different rate limiting policies based on the user, service, or endpoint accessed.
Using our restaurant analogy as an example, imagine that we have guests in our restaurant who are all verified, certified, and authorized to enter the restaurant. But these guests are especially hungry and thirsty, and constantly order food and drinks. At some point, this becomes unmanageable for restaurants. The cooks and waiters were overworked and unable to take any new orders, the plates and cutlery were running out, and the food in the kitchen was running out.
Chefs can step in and limit the number of orders a customer can make, for example, by limiting the number of entrées or wines that can be ordered per hour, and a limit limit can ensure that the restaurant is not overloaded and can still serve new customers.
The API gateway manages the routing of incoming requests to the appropriate backend service based on various criteria such as URL paths, HTTP methods, headers, or query parameters. It's an integral part of a microservices architecture, where different services handle different parts of APIs.
Going back to our previous restaurant metaphor, depending on the purpose of the guests, the maître d'être d't direct them to the right person or place – diners lead to waiters, guests who just want to drink lead to the bar, and people who ask to book restaurant events lead to the event coordinator.
This involves modifying requests and responses as they pass through the API gateway.
For requests, this could mean adding, removing, or modifying headers, rewriting URLs, or even changing the request body. For responses, this may involve changing the state**, modifying the head, or transforming.
This capability allows the API gateway to act as an intermediary that can translate requests and responses to meet the needs of clients and back-end services.
Back-end services can also perform this kind of request and response translation. The decision about which component (API gateway or backend service) to do the conversion is subjective. However, API gateways are often an ideal place to centralize this transformation with minimal effort, rather than making custom transformations in each backend service.
For example, if a restaurant guest is not gluten tolerant, then their order must be changed to ensure that the meal does not contain any gluten.
The logic of this order switching can be achieved by the foreman clearly indicating which ingredients should be excluded from the menu before sending the order to the chef, or in the kitchen by the foreman simply telling the chef that the guest has ordered a gluten-free dish and asking him to modify the order accordingly.
A microservices architecture is an approach to developing software that breaks down large applications into smaller, independent components called microservices. Each microservice is a self-contained unit with a specific function or responsibility within a broader application.
The following diagram shows a simple microservices architecture for a basic e-commerce application.
Client: These are different clients that interact with the e-commerce platform. They can be mobile apps, web browsers, or any other third-party applications.
API Gateway: Serves as a single point of entry for all types of clients, routing requests to the appropriate microservice based on the nature of the request (user-related, product-related, order-related).
services: These are eCommerce-specific examples of microservices. Each service handles different aspects of the business logic, such as user profiles, product catalogs, and order processing.
Databases: Each microservice has its own dedicated database, ensuring data isolation and service independence.
In this example, the API gateway is:
Make sure that every customer's request goes throughValidation
Make sure customers get it before they do something like ordering or writing a product reviewAuthentication and authorization
Rate limitingrequests to ensure that the service is not shut down due to malicious behavior of sending a large number of requests.
Depending on different criteria, such as URL paths, HTTP methods, headers, or query parameters, it willThe client requests the routeto the appropriate back-end services.
ProcessingRequest and response transformation。For example, a response from a Product Service might have a complex format and extensive detail. The API gateway converts this response into a format that is more suitable for mobile applications. This could involve simplifying the data, converting it to a lighter format, or extracting only the essential information needed for the mobile app.
API Gateway is a fully managed service that makes it easier for developers to create, publish, maintain, monitor, and secure APIs at almost any scale, and because it's fully managed, it abstracts the work required to manage and maintain the underlying infrastructure – which is handled by the cloud provider providing the service.
The API gateway acts as a middleman between the client and the many services that need to be accessed, and it handles request validation, authentication and authorization, rate limiting, request routing, and request response translation.
It is particularly useful in microservices architectures as a central entry point for managing, processing, and routing incoming requests to the appropriate microservices, and plays a vital role in simplifying client interactions and providing a central interface to a set of microservices.