What Is a REST API?
November 20, 2020

What Is a REST API?

API Lifecycle Management

REST APIs are everywhere. Spend any amount of time working with APIs, or reading API documentation, and you will certainly come across the term REST API or RESTful API.

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What Is a REST API?

A REST API is an application programming interface (API) that uses a representational state transfer (REST) architectural style. The REST architectural style uses HTTP to request access and use data. This allows for interaction with RESTful web services. 

The concept of REST was introduced in 2000 by Roy Fielding, a noted computer scientist who has influenced the development of many WWW standards. REST was, and remains, a core architectural principle for the web in general.

It has gained traction as an alternative to WS* and SOAP-based web services for consumption within mobile devices, the "internet of things", and many open-web consumer-facing use cases.

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Why Are REST APIs Popular?

REST APIs are popular because they are user-friendly and easy-to-understand. REST is now considered the standard protocol for web APIs. And REST APIs are often used instead of SOAP APIs. Compare SOAP vs. REST APIs >>

Why Use REST APIs?

REST APIs are similar to SOAP in architectural terms.

REST works on top of the HTTP transport. It takes advantage of HTTP’s native capabilities, such as GET, PUT, POST and DELETE. When a request is sent to a RESTful API, the response (the “representation” of the information “resource” being sought) returns in either the JSON, XML or HTML format. A RESTful API is defined by a web address, or Uniform Resource Identifier (URI), which typically follows a naming convention.

In contrast to SOAP, REST is easier to work with and more flexible:

  • No expensive tools needed in order for interaction with web services.
  • Shorter learning curve.
  • More efficient (XML, used in SOAP messages, is longer than REST’s message formats).
  • Faster, with less processing required.

You can even use REST APIs with GraphQL.

Whether you're using REST or SOAP API, it's important to consider the complete API lifecycle

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6 REST API Architecture Constraints

A true REST API architecture does have constraints. 

Uniform Interface

The fundamental design to any RESTful system, which differentiates between a REST API and non-REST API. This constraint simplifies the architecture by providing a uniform way of interacting with a given server (irrespective of device or application type).

Client Server

This constraint essentially says that servers and clients should only know resource URLs, and that's all. There are no dependencies. Any can be developed and replaced independently so long as interface between them is unaltered. 


This constraint, by definition, means all client-server interactions are stateless. Every request is treated as new, with no sessions nor history. If the end-user requires a stateful application, then each request from the client then must contain all necessary information to service the request.


Caching in REST should be applied to resources when applicable. This can be implemented on both the server or client side. 

Layered System

REST enables using a layered system architecture, where perhaps the APIs are deployed on one server, data is stored on another, and requests are authenticated on yet another. 

Code on Demand

This optional constraint means that you are able to, upon need, provide executable code to the client.

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What Is a REST API Example?

Here's an example of a REST API. Imagine that MyWidgets.com, a fictional online store selling widgets, wanted to allow a mobile app to have access to its product catalog database. And you want to create an API

It might create a RESTful API with a URL of http://api.mywidgets.com/ catalog. The mobile app developer could pull the catalog onto the app by writing an HTTP request of “GET” to this URL.

To get a specific item from the catalogue, the developer would write GET to a version of the API that contained the product number, such as the following: http://api. mysoles.com/catalog/[sku].

When the RESTful API received the HTTP request, it would return the product information in JSON or some other web standard format.

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Maximize Your REST APIs

To maximize REST APIs, you need an API platform like Akana

Create and Publish

Akana makes it easy to create and publish REST APIs. This means you can deploy APIs faster and accelerate your time-to-market.

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Connect to Mainframe Applications

With Akana, you can even connect to mainframe applications. Sola by Akana is a mainframe API platform. Using Sola's REST Designer makes it quick and easy to access any API in your portfolio using REST protocols.

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Manage and Monitor

With Akana, you can also easily manage and monitor APIs throughout their lifecycle. This means you can improve API performance. 

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Monetize and More

With Akana, you can monetize your APIs — and so much more. This means you can increase your revenue and overall API ROI

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Get Started With Akana

See for yourself why Akana provides the best platform to manage your REST APIs. Start your free 30-day trial today.


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