How does web API design work?

3 min read
Updated: Sep 15, 2019

Many APIs claimed to use a RESTful approach. We didn’t have any other choice than to believe them at first, but a detailed examination showed that many of them hadn’t fulfilled the requirements of the RESTful design.

The first person who dealt with the RESTful design was Dr. Fielding, who exposed RESTful design constraints in his doctoral thesis. According to him, RESTful design carries six constraints within. Three constraints are well known and visible, while the other three aren’t. We will discuss them in the following paragraphs.

A uniform interface

A uniform interface is the most accurate proof of a server and client are segregation. This will provide the independent application evolution, without the need for services, models, and actions along with the API layers. A client communicates with the server by using one language only. A uniform interface is the provider of this easy way of communication, which is independent of the backend architecture. Communication flows through by using HTTPS resources and via the URI.

An optional constraint

This constraint is probably the least known, as it is optional. Demanding the code will provide easy delivery of the code and its applets by using the applications’ API. This way you can create a strict code-independent smart application. When the doctor wrote about this constraint 18 years ago, the developers doubted in his words. However, today’s trend of developing AI enabled applications showed that the doctor had right and that we all need this constraint more than ever.

A layered system

A layered system might seem complicated at first, but it is actually very simple. Every layer is responsible for a specific set of the rules and has a special function. This might remind you of a Model View Controller.

The controller in a layered system focuses on the incoming actions, while the layers work independently, maintaining mutual communication. RESTful API design functions the same, as each segment is hierarchy-organized. This further produces a scalable and modular architecture.

Developers can easily encompass the legacy system through the layered systems if needs. This way, they have the option to move some of the frequently used functions from one library into another, shielding common parts of the design at the same time. Meaning – the system has the ability to take systems in and out of the system. The layered system promotes flexibility, but it requires loose models.

One more feature of the layered systems is their security. The layered system prevents possible attacks directly at the proxy layer. If it was oppositely, the attacks could be able to get into the server’s architecture. Any critical data about the architecture is well hidden behind a firewall, which keeps the client from communication with the ingenious server.

A word for the end

The constraints we discussed above are widely known as the Representational State Transfer or REST. Each of them is associated with another, creating a powerful, complex, and flexible programming interface. These constraints exactly make it possible to develop applications the way we do it today.


Sophia Rodreguaze


Sophia is the contributing editor at She writes about anything and everything related to technology.

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