Building a REST API helps third-party systems and services communicate with your internal applications. In particular, REST APIs are useful for ETL (extract, transform, load) and data integration workflows. They make it easy to exchange information between various websites, databases, and SaaS (software as a service) applications.

That said, how can you make a REST API? Keep reading this all-in-one REST API tutorial to find out.

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What is a REST API?

In computing, an API (application programming interface) is a collection of functions and protocols that enables two software applications or systems to communicate with each other. The API defines a common set of commands, as well as the appropriate way to invoke these commands. 

As such, an API adds a layer of abstraction on top of the “messy” technical details of the API implementation. By adding an abstraction layer, APIs make development less complex and help to clean up the codebase while software components become more reusable and modular.

One good analogy for an API is the menu at a restaurant. The menu represents the possible interactions that you can have with the restaurant (i.e., the types of dishes that you can order). You don’t need to know what’s going on in the kitchen behind the scenes to receive and enjoy your meal. Similarly, when using an API, you don’t need to know the specifics of how the system retrieves the data you want from behind the API — you only care about the answer you get back.

So, what is a REST API? REST (representational state transfer) is a software architectural style commonly used for building web services such as APIs. According to a 2017 study, 83 percent of APIs now use the REST architecture, while 15 percent use the older SOAP protocol.

REST comprises six principles (five mandatory and one optional). An API that complies with these principles qualifies as a RESTful API:

Uniform interface: All clients should be able to interact with the REST API in the same manner, whether the client is a browser, a mobile app, or something else. The REST API is usually accessible at a single URL (uniform resource locator) — for example, “https://api.example.com.”

Client-server architecture: In REST APIs, the client and server are two separate entities. Concerns about the API interface are separate from concerns about how the underlying data is stored and retrieved.

Statelessness: REST requests must be stateless; the server does not have to remember any details about the client’s state. This means that the client must include all necessary information within each API request it makes.

Cacheability: REST servers can cache data by designating it as cacheable with the Cache-Control HTTP header. The cached result is ready for reuse when there is an equivalent request later on.

Layered system: The REST client does not know (and does not need to know) if it is communicating with an intermediary layer in the architecture, or with the server itself.

Code on demand (optional): The client can optionally download code such as a JavaScript script or Java applet in order to extend its functionality at runtime.

How to Make a REST API

Now that we’ve defined REST APIs and gone over the principles and benefits, there’s just one question left: how can you make one?

There are as many ways to build a REST API as there are web development libraries and frameworks. Below are just a few examples:

Python Flask: Python Flask is a web framework written in the Python programming language. A Flask-RESTful extension is a lightweight tool that allows you to spin up REST APIs quickly.

Node.js: The Node.js framework restify, which is used by tech giants such as Netflix and Pinterest, helps you build production-ready REST APIs at scale.

Ruby on Rails: Beginning with Rails 5, Ruby on Rails includes an “API mode” for easily building web APIs.

Spring: The Spring framework for Java provides an in-depth tutorial for making REST APIs.

With so many useful platforms and tools for building REST APIs, there’s little reason to make one from scratch these days. In addition, the question of “how to make a REST API” highly depends on implementation and programming language, which makes it nearly impossible to write a REST API tutorial that covers all the options in detail.

Instead of diving into the technical specifics, we’ll use this space to offer some evergreen best practices for building REST APIs with the tool, framework, or library of your choice:

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JSON vs. XML: JSON and XML are the two de facto standards for sending and receiving data in REST APIs. Web programming languages such as Python, JavaScript, Ruby on Rails, and Java all have tools for parsing and working with XML and JSON. XML is usually the better choice when you need to include metadata and document markup, whereas JSON (being less verbose) is usually preferable for other use cases.

Name your endpoints appropriately: Users of REST APIs typically expect the API to adhere to various naming conventions. Some of these conventions include:

  • Using nouns instead of verbs when naming API endpoints (e.g., “https://api.example.com/users” instead of “https://api.example.com/getUsers”)
  • Using lowercase ASCII characters
  • Separating words with hyphens instead of underscore or camel case (e.g., “https://api.example.com/user-ids” instead of “https://api.example.com/user_ids).

Consider data security: REST APIs may exchange sensitive and confidential information, so data security is essential. Consider using the SSL/TLS protocol for encrypting private data. Also, enforce access control so that users cannot view the information they don't need to access in the first place.

Fail gracefully: Be sure to include error handling in your REST API so that users can understand the cause of the error and potentially correct it. The HTTP error status codes you might use for your REST API include:

  • 400 Bad Request (a client request error, such as bad syntax or an invalid message framing)
  • 401 Unauthorized (the client has not been authenticated)
  • 403 Forbidden (the client is authenticated but not authorized to access the resource)
  • 404 Not Found (the requested resource is not found)
  • 502 Bad Gateway (the server received an invalid response from another server)
  • 503 Service Unavailable (the server is overloaded or under maintenance)

How Xplenty Can Help with REST APIs

 

As mentioned above, REST APIs are helpful for extracting your data from one or more sources and moving it to a centralized repository, often a data warehouse or data lake. But how can you streamline the REST API creation process for data integration?

Xplenty can help. The Xplenty platform is a powerful, feature-rich ETL and data integration tool with a simple drag-and-drop interface and more than 100 pre-built connectors — including a REST API connector.

Related Reading: Xplenty’s REST API Connector

The Xplenty REST API connector is ideal when you’re trying to retrieve data from a third-party website or service, such as YouTube or Instagram. You can also make REST APIs that fetch data from internal systems but do not fully expose the database layer.

Ready to start building REST APIs for your enterprise data with Xplenty? Then contact our team of data experts to discuss your business needs and to start your 14-day pilot of the Xplenty platform.

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