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What is a REST API and How Does It Work?

Angela Stringfellow

Last updated on

Integrations are the lifeblood of the internet. They’re the reason why you can buy something on Amazon, share photos on Instagram, or catch up on news through CNN. Most applications rely on APIs, or application programming interfaces, to communicate with each other and accomplish tasks behind the scenes.

At their core, APIs standardize how different applications talk to each other. There are different types of APIs that developers can use, such as notification APIs to send notifications to users from apps or websites and email APIs to send large volumes of transactional emails or marketing emails. Multiple APIs may be involved in some processes. For example, to send push notifications, developers must use both a notification API and a push API.

REST API is a popular option for applications like Facebook, YouTube, Twitter, Google, and much more. In fact, REST API is the unofficial standard for most applications. Whether you have a multinational enterprise or a small startup, it’s important to understand what REST API is, its six principles, and its benefits.

What is a REST API?

An API integrates two different applications so they can work together, even though they’re separate programs. If you want to retrieve information from another application, an API is the bridge that allows communication between both applications. For example, Facebook uses Instagram’s API to automatically share your Instagram posts to Facebook.

REST, or representational state transfer, is a type of API that developers can use to connect different applications. It’s also known as a RESTful API.

Created by Roy Fielding in his dissertation in 2000, REST isn’t a protocol or a standard, but a set of rules for how applications communicate with each other. REST APIs are a common way to connect applications because their unique architecture means they’re faster and more lightweight than other APIs.

How Does a REST API Work?

To understand how a REST API works, it’s important to know which parties are involved in a RESTful API:

  • Client: The client is the user or the application accessing an API. As a client, you’re using the API to request information.
  • Resource: The resource is the information that the API gives to you, the client. For example, when you pull up someone’s Instagram profile, that’s a resource. Every resource comes with its own unique resource identifier, or URI. Because every URI is unique, the API knows exactly which resource to give to you.
  • Server: The server is the application that receives a request from a user or application. The server houses all of the resources that the client needs to access. Because you don’t want to give users direct access to your server, you can use an API to interact with the client without granting direct access to your database.

A REST API will send an HTTP request to the server to create, read, update or delete records. REST API can send the information in multiple formats including JSON (which is the most popular), HTML, XLT, Python, PHP, or plain text.

In practice, let’s say you’re developing an app that integrates with Facebook. You can create a REST API with Facebook for your users to request information on a Facebook user, which is a resource. Facebook then gives you the resource, which includes data like the user’s photo, status updates, and more. The REST API will package this data in a consistent, clear way that your application can put to work more quickly than it could with other APIs.

The 6 Principles of REST APIs

Not sure if an API is RESTFul? Your API must meet the mandatory first five criteria of REST APIs (the sixth is optional).

1. Client-Server Separation

REST only allows the client and the server to interact in one way. With REST APIs, only the client can initiate the request. This is beneficial because it decouples the client and server, keeping both applications independent from each other.

2. Uniform Interface

RESTful APIs require you to follow a specific protocol, or formatting method, for your requests. Uniformity is critical here so the two applications can work together with fewer errors. By standardizing communication, there’s no need to translate requests with a RESTful API, which makes them much faster.

3. Statelessness

To qualify as a RESTful API, every interaction needs to be independent. The server should process every client request as a new request. It shouldn’t remember anything that the client asked for in previous requests. In development, this is beneficial because it significantly reduces the memory required for you to operate a server.

4. Layered System

A client and a server don’t always have a direct line to each other. There are intermediaries between them that distribute traffic and keep both applications secure. However, REST API requires you to build the API so that you can’t even tell if you’re communicating with the application or through an intermediary—the extra layers shouldn’t affect the interaction.

5. Cacheability

Caching happens when you store media or data on a client device instead of on your own server. RESTful APIs are so fast because they require the client to store data locally. This means the data can load much more quickly the next time the client returns to your site or application.

6. Code on Demand (Optional)

The final principle of RESTful APIs is optional, but it’s still important. With this principle, you can use the API to send code to the client as a reply. The requirement is that this can only execute this on-demand, as needed.

The Benefits of RESTful APIs

A REST API isn’t always the best choice for an API, but it’s very common. Done well, a REST API is beneficial because it’s:

  • Simpler than other APIs: APIs like SOAP and XML-RPC have stricter requirements for developers. REST has fewer requirements, which means it’s lighter, faster, and more scalable for developers. Its simplicity and ease of use is the reason why so many developers use RESTful APIs for mobile apps.
  • Better for the user experience: Users are demanding better experiences. If you want to meet these demands and become more competitive, you should use RESTful APIs to deliver smarter, faster experiences for your users.
  • Easier to control: RESTful APIs help you maintain a greater degree of control over your data. This allows you to clearly define who has the power to do what within your application.

Simplify Your Notification System with MagicBell’s RESTful API

REST APIs allow developers to connect applications with fewer delays and resources, which ultimately makes for a smoother, faster user experience. As long as you follow the five mandatory principles of RESTful APIs, you still have the freedom to customize the API as needed for your next project.

Use MagicBell’s extensible REST API to send notifications to your users and to retrieve notifications that you’ve sent to users in the past. With a single request, MagicBell delivers notifications to your users no matter where they are – including push notifications, email notifications, and in-app notifications – while syncing notifications across devices and tabs so you don’t ever notify a user twice.