API Architecture Explained in 5 Mins or Less

An API or Application Programming Interface is an essential component of most software architectures. It paves the way for different software or services to talk to each other efficiently.

APIs provide a sense of abstraction by exposing a bunch of required functionalities and abstracting sensitive or private data. Authentication and authorization allow you to secure your APIs from unauthorized access or tampering with data.

Software developers leverage various APIs to build, test & optimize software systems in a structured manner. It allows them to interact with a software system through a set of pre-defined rules or protocols.

What Are API Gateways?

In a software system, in most cases, there isn’t just one single API that handles every service a software provides; rather, there are a bunch of APIs talking to each other collaboratively to send data to the client.

An API gateway, as the name suggests, acts as an entry point for various API requests and routes them to their particular API service or a microservice. This transfers the load to send multiple API requests from the client to the API gateway, improving client performance.

For example, a food delivery application has a bunch of microservices for restaurants, users, vendor ratings, delivery partner ratings, routing algorithms, map service, and much more. So, it would make much more sense for the client, i.e., the end user application, to request a single API, and then that API gateway routes requests to relevant microservices.

Another great benefit you get when implementing an API gateway is security. You can set up multiple authentication and authorization systems to prevent attackers from exploiting resources.

Building Blocks of an API Architecture

There are several building blocks of an API architecture, some of which are listed here:

#1. API Interface

An API interface clearly defines the methods or functionalities that can be accessed without revealing their implementation details. It defines a set of rules and methodologies that must be used to retrieve or modify resources.

For example, in a RESTful API, you have HTTP methods such as GET, PUT, POST, DELETE, etc., to interact with resources.

#2. Route Controllers

Controllers play a key role in API gateways as they handle all the API traffic from multiple clients and route them to a relevant API service.

On top of it, controllers can also perform request validation, response handling, authentication, etc.

#3. Data Access Models

Every resource in a database has a certain type of structure or shape, and it is better to define that structure beforehand for validation purposes. It is also known as a schema. The payload coming from the client can be validated against the schema and then added to the database.

It prevents any invalid or tampered data from entering the database.

Components of an API Architecture

• API Services: These are services that provide access to a particular resource or a set of resources. Multiple API services are required in a large-scale application. These services are decoupled from each other and manage resources independently.
• Documentation: API documentation is necessary for developers to understand the effective use of API and the methods it exposes. The documentation can include a list of endpoints, best practices, request formats, error handling, etc.
• Analytics & Monitoring: An analytics dashboard is a key component because it provides metrics such as API traffic, error rates, and performance, among many other insights.

Commonly used API Design Architectures

REST – Representational State Transfer

REST is an API architectural style that uses the HTTP protocol and enables stateless communication between the client and the server.

In REST, the resources are identified by URLs, which have specific endpoints for every resource. REST relies on HTTP methods such as GET, PUT, POST, etc. to modify and create resources. The APIs which implement REST architecture are known as RESTful APIs.

SOAP – Simple Object Access Protocol

SOAP is a messaging protocol based on XML. Messages in SOAP are encoded in XML documents and can be transferred from a SOAP sender to a SOAP receiver. There can be one or more services through which the message can pass before reaching the receiver.

The main difference between SOAP and REST is that REST is an architectural design relying on HTTP, but SOAP is itself a protocol that can use various underlying protocols such as HTTP, SMTP, etc. The response data format in SOAP is XML.

gRPC – Google Remote Procedure Call

Remote Procedure Call (RPC) is a technique in which a function on a remote server is called by a client as if it was called locally. gRPC is an open-source framework developed by Google. It uses proto-buffers (protocol buffers) which is a language-agnostic way to write and encode structured data.

The data in proto-buffers is compiled by a gRPC compiler, making it interoperable. For example, if the client code is written in Java and the server code in Go, then the data specified in proto-buffers is compatible with both languages.

GraphQL

GraphQL is an open-source query language and runtime for building APIs. It allows clients to access multiple resources by hitting a single entry point or endpoint. A particular resource is not tied to a particular endpoint. You get what you specify in the request query.

You need to define a strongly typed schema for a particular query and a resolver function that will get executed for that query. In order to modify resources, there is a mutation query that you need to specify in GraphQL.

API Architecture Deployment – Best Practices

No matter how well you design your API architecture, if it fails in production, it’s of no use. It must deliver according to real-world scenarios. Here are some key practices to make the API architecture ready for production:

✅ Use API gateway

API gateway aids in the effective routing of API queries. An API gateway can also handle security and validation.

✅ Perform API Testing

Prior to launch, make sure your API has undergone comprehensive functional, integration, and performance testing. Frameworks for automated testing can aid in streamlining this procedure.

✅ Focus on Scalability

Create a scalable API architecture that can manage rising traffic demands. To dynamically alter the number of API instances based on demand, think about employing auto-scaling techniques.

✅ Choose Hosting Wisely

Consider hosting providers that give scalable solutions to cope with rising traffic and customer demand. Be on the lookout for features like load balancing, auto-scaling, and the flexibility to assign more resources as necessary.

Make sure the hosting provider can match the performance specifications of your API, especially during periods of high demand. Also, explore serverless options if that fits your business needs.

How to Choose the Appropriate API Architecture?

Selecting an API architecture depends on the following considerations:

• Business Requirements: Analyze the business goals that need to be fulfilled with the API and understand the application flow.
• Use Cases: Asking the question of why you need an API in the first place will help you a lot. Figuring out different use cases will help you better design or select an API architecture.
• Scalability: Again, understanding the business requirements and use cases will help you design a scalable API architecture that is also performant.
• Developer Experience: Make sure the API architecture is easy to grasp so that the new, onboarded developers can easily understand it without any hassle.
• Security: Probably the most important aspect of API architecture is security. Ensure your API architecture is secure enough and compliant with privacy laws.

Next, we will explore learning resources to improve your API architecture design skills.

Learning Resources

#1. Mastering API Architecture: Design, Operate, and Evolve API-Based Systems

This book will help you learn API fundamentals and explore practical ways to design, build, and test APIs.

Preview	Product	Rating	Price
	Mastering API Architecture: Design, Operate, and Evolve API-Based Systems		$39.51	Buy on Amazon

It also teaches you how to operate, configure and deploy your API system. This book covers everything from API gateways, service mesh, security, TLS, and OAuth2 to evolving existing systems.

#2. Software Architecture: REST API Design – The Complete Guide

If you are interested in learning about RESTful APIs and how they are designed, this course on Software Architecture is for you.

It covers authentication, authorization, documenting REST APIs, and various performance techniques to further optimize your API design. What’s great about it is that it covers HTTP basics and the Postman API testing tool.

#3. REST API Design, Development & Management

Tutorials on various API management platforms, such as Swagger, Apigee, and Mulesoft, are the key highlight of this course. This course is for those who want to explore applications of REST APIs and are interested in architecting them.

#4. Designing RESTful APIs: Learn to Design API from Scratch

Creating a REST API from scratch is what you’ll get from this course on Designing RESTful APIs. Requests, response, API design, and operations are some useful topics that are covered. If you are a beginner who is still learning the basics of REST, then I think you should go for it.

Final Words

You may choose the best API architecture in accordance with your business goals and technical goals by taking into account the integration needs, performance considerations, security requirements, and future scalability and extensibility.

Next, kickstart your software testing career with these courses and resources.