Designing REST-APIs: A Comprehensive Guide

2023-07-03

RESTful APIs are the backbone of the modern web. They allow different devices to communicate and share data over the web seamlessly. This post will explore the best practices for designing RESTful APIs.

1. Start with your customer in mind

Before diving into the technicalities, make sure that you always consider your customer. Ask questions like: Who will be using your API? What are their needs? Design your API to be user-centric. You should Understand Your Audience and tailor your API to its intended audience. If you're building an internal tool, don't be shy and talk to the people who will work with your API. Talking to your customer and understanding what the API should be all about is probably the most important part of designing good APIs.

2. Organize your API around resources

An API should always be organized around resources. A resource is an object or representation of something with some associated data, and there can be a set of methods to operate on it. URIs identify resources.

So you shouldn't give your endpoints names like /get-users or /get-products. Instead, you should use the resource name in plural forms, like /users or /products.

Instead of using verbs, you should use HTTP methods to operate on these resources. The HTTP methods you will most likely encounter in your day-to-day life will be: GET, POST, PUT, PATCH, and DELETE. Those methods are used in the following situations:

  • POST: Use this method if the end-user is to send data to the API.
  • GET: Use this method if the end-user is to retrieve data after the API queries the database.
  • PUT: Use this method if the end-user updates existing data in the database.
  • PATCH: Use this method if the end-user needs to correct or replace existing data in the database.
  • DELETE: Use this method if the end-user deletes any information or data from the database.

3. Think about the structure of your API

When your API starts to grow, you must think about how you structure your resources. To do so, you can use sub-resources. Sub-resources are resources that are nested within other resources. For example, if you have a resource called users, you could have a sub-resource called users/1/posts. This would return all posts from the user with the ID 1. Here are some guidelines on how to use sub-resources:

  • Group entities together that are related to each other. For example, if you have a resource called users, you could have a sub-resource called users/user/posts. This would return all posts from the user with the ID 1.
  • Use params to identify sub-resources. For example, if you have a resource called users, you could have a sub-resource called users/1/posts. This would return all posts from the user with the ID 1.
  • Don't nest too deep. Resources should be easy to understand. If you must nest more than two levels deep, consider using a query parameter instead.
  • Use query parameters to filter, sort, or paginate your resources. For example, if you have a resource called users, you could have a query parameter called users?sort=asc. This would return all users sorted by their ID in ascending order. Furthermore, pagination is a great way to reduce the load on your server. Instead of returning all resources simultaneously, you can return them in chunks. For example, if you have a resource called users, you could have a query parameter called users?limit=10&offset=0. This would return the first ten users. You must change the offset to 10 to get the next 10 users. This would return the next ten users.

4. Use versioning to manage breaking changes

We should ensure we don't break any existing clients whenever we change our API. To do so, we should use versioning. Versioning is the process of assigning unique version names or unique numbers to unique states of computer software. Within a given version number category (major, minor), these numbers are generally assigned in increasing order and correspond to new developments in the software.

While there are different ways out there you could version your API, like Query Params, Headers, or Media Type, I prefer to use the URI. So you would have something like https://api.example.com/v1/users and https://api.example.com/v2/users.

5. Use the right HTTP status codes

HTTP status codes are standard response codes given by website servers on the Internet. They are used to communicate with the client about the request's status. There are five classes of HTTP status codes:

  • Informational responses (100 – 199)
  • Successful responses (200 – 299)
  • Redirection messages (300 – 399)
  • Client error responses (400 – 499)
  • Server error responses (500 – 599)

The most common HTTP status codes you are going to encounter are:

  • 200 OK: The request has succeeded.
  • 201 Created: The request has been fulfilled, creating a new resource.
  • 400 Bad Request: The server cannot or will not process the request due to an apparent client error.
  • 401 Unauthorized: The request has not been applied because it lacks valid authentication credentials for the target resource.
  • 403 Forbidden: The server understood the request but refused to authorize it.
  • 404 Not Found: The origin server did not find a current representation for the target resource or is unwilling to disclose that one exists.
  • 500 Internal Server Error: The server encountered an unexpected condition that prevented it from fulfilling the request.

Make sure to use the proper HTTP status codes for your API. This will help your clients to understand what's going on and how to react to it.

6. Use caching to improve performance

Caching is a great way to improve the performance of your API. It allows you to store data in memory and serve it to your clients without having to query the database every time. This can be especially useful if you have a lot of requests coming in at once. You can use caching to reduce the load on your server and improve the performance of your API. Some options for caching are:

  • Redis: Redis is an open-source, in-memory data structure store used as a database, cache, and message broker.
  • Memcached: Memcached is a general-purpose distributed memory caching system.

Conclusion

In this post, we've explored the best practices for API design. We've learned that we should always start with our customers in mind and organize our API around resources. We've also learned that we should use versioning to manage breaking changes and use the proper HTTP status codes. Finally, we've learned that we should use caching to improve performance. While there are many more things to consider when designing an API, these are some of the most important ones. When implementing an API, it's essential to keep these things in mind, but 1.-5. are the most important ones. If you follow these guidelines, you can design a good API that will be easy to use and maintain. Caching and other performance improvements are also essential, but they're not as important as the first five points when implementing our API. I hope you've enjoyed this post and learned something new. If you have any questions or feedback, please don't hesitate to contact me. Thanks for reading!