When it comes to the interaction between the client (for example, a web application) and the server, it is impossible to bypass two popular approaches: REST API and GraphQL. Both of them solve the same task — data transfer between the client and the server, but they do it in different ways. To understand their differences, let's sort everything out using simple analogies.

What do the library and API have in common?

Imagine that you are in a library. You want to take a book, but you can't just walk into a warehouse and start looking for it. Instead, you contact a librarian who knows where the books are stored and can quickly find the one you need. The librarian in this case is the API (Application Programming Interface). It acts as an intermediary between you (the client) and the books (the server).

The API helps applications "communicate" with each other by providing clear rules for requests and responses. For example, when you open a weather website, your browser sends an API request to the server to get up-to-date temperature data. Without the API, such interaction would be much more difficult to organize.

Now that we understand what an API is, let's compare two popular approaches: REST and GraphQL.REST API: How does it work?

REST (Representative State Transfer) is an architectural style that relies on standard HTTP methods: GET (get data), POST (create data), PUT/PATCH (update data) and DELETE (delete data).

Let's return to the analogy with the library. Imagine that you have a list of predefined shelves where books are stored. If you need a specific book, you approach the librarian and say: "Give me the book from shelf No. 3." The librarian takes it out and hands it to you. This is similar to the REST API: you have fixed "shelves" (endpoints), and you request data from there.Example:GET /users — get a list of all users.GET /users/1 — get information about a user with an ID

1.POST /users — create a new user.REST is convenient because it is predictable and easily structured. However, it has limitations. For example, if you need to get data from several "shelves" at the same time, you will have to make several requests. This can be inefficient, especially if the data is needed urgently.GraphQL: how does it work?GraphQL is a more flexible approach. Instead of relying on fixed endpoints, GraphQL allows the client to specify exactly what data it needs. Let's return to our library. Now imagine that you can tell the librarian, "I need chapter 5 from the book 'History of Art,' as well as the first two pages from the book 'Physics for Beginners.'" The librarian collects everything you asked for and gives it to you in one package.In GraphQL, you send a single query in which you describe what data you want to receive. The server analyzes this request and returns only what you requested. This is especially useful if you need to collect data from different sources or if you want to minimize the amount of data transferred.

Query example in GraphQL:

graphqlCopy123456789101112{user(id: 1)

{nameemailposts

{titlecomments

{text}}}}

This request receives the user's name and email address, the titles of his posts, and the texts of comments on these posts — all in one request.When to use REST?

REST is great for projects where:The data structure is relatively simple and stable.We need predictability and standardization.The development is carried out by a small team, and there is no need for complex server configuration.For example, if you are creating a blog or an online store, the REST API would be a great choice. It is easy to implement and well documented.When to use GraphQL?GraphQL is ideal for projects where:

The data is complex and interconnected (for example, social networks).

Clients only need to receive certain parts of the data.T

We try to minimize the number of requests to the server.

For example, if you are developing a mobile application where it is important to save traffic and download time, GraphQL will be a great solution.

Both approaches have their advantages. REST is a classic that works like a Swiss watch in most cases. GraphQL is an innovation that offers more flexibility and control over data. The choice between them depends on your needs: if simplicity and standardization are important, choose REST; if flexibility and efficiency are needed, pay attention to GraphQL.

Whatever technology you choose, the main thing is to understand its principles and apply it correctly in practice. After all, just like in a library, success depends not only on books, but also on how you search for them!