REST API: what it is, how it works, advantages and disadvantages

The REST API is one of the most versatile and widely used APIs in the web world, thanks to its power to simplify communication between web applications.

It also represents a secure method for synchronizing applications and exchanging information securely.

Like all APIs, the REST API follows a series of protocols to improve communication between applications and systems. However, to better understand how it works and how it differs from others, you need to understand what an API is.

And in this article, we'll tell you from A to Z what an API is and what benefits it can offer you if you're looking to specialize in web development.

So first things first:

What is an API?

An API, or an Application Programming Interface, is a link interface between two web applications or between two remote systems. 

In other words, an API would be the bridge between two web portals, or the connection where the two applications are integrated. All through a series of protocols and functions.

APIs have been the basis of integration and web applications for quite some time. And they are more than indispensable to the web as we know it.

Social sharing buttons, video integrations in your messaging apps, integrated GPS apps... Everything works through APIs.

What is a REST API and what is it for?

REST (Representational State Transfer) is an architectural style that defines a set of principles for designing distributed systems on the web. A REST API is an API that follows these principles, which makes it perfect for communications in web environments.

In simple terms:

• A REST API is an interface that allows different applications to interact with each other over the web using HTTP (Hypertext Transfer Protocol) requests. 

• Instead of sending information in a specific format, such as XML or JSON, REST requests use HTTP methods to transmit information between systems.

In addition, REST APIs use URIs (Uniform Resource Identifiers) to identify absolutely all resources available on the web, including web pages,

images, videos, documents... 

When you make a request to a given URI, the REST API provides you with all the information you need to work with.

For example, if you want to search for information across your platform, you can make a request to a specific REST API that has the weather information, using a URI like this one: 

https://api.weather.com/clima/London. The REST API returns the weather information in JSON format, which you can then use to display the information in your own application.

APIs can be thought of as a gateway between clients and the resources of an application or web page. 

1. Clients

All those potential users who want to use the Web to access data are called "clients". That is, a person or a computer program that uses the API is called a client. 

Let's go with another example, developers have the possibility to create, for example, programs that allow access to weather information from a weather system. By going directly to the weather website, the same information can be accessed from the browser.

2. Resources

The data that some apps offer to different users are known as resources. Any type of data can be used as a resource, including text, numbers, images, and videos.

The device responsible for providing the resource to the potential client is also called a server. As long as security, control, and authentication are maintained, companies use APIs to share their resources and offer web services. They can also choose which clients have access to certain internal resources thanks to APIs.

RESTful Principles 

1. Uniform interface

Fundamental to any RESTFull web service, it indicates the transfer of data in a standard way. It establishes 4 architectural constraints

1. Every request must identify the resources. 

2. Every client has sufficient information in the representation of the resource so that it can be removed and/or modified according to their needs. This is achieved by sending metadata.

3. Clients obtain information on how to continue with the representation process. This is achieved through the sending of self-descriptive messages by the server, where the metadata of how the client can use them in an ideal way are contemplated.

4. The client receives information about all other resources of interest necessary for the fulfillment of the assigned task. The server does this by sending hyperlinks in the representation so that the client can dynamically discover more resources.

2. Stateless technology

When we speak of "stateless" technology, we’re talking about a communicative method in which the server completes the various requests made by the client, regardless of the previous ones. 

In other words, the client can continue to make requests, since they are "stateless" or separate from the rest. This is what allows the REST API architecture to accomplish all tasks.

3. Layered system

In this type of "layered" architecture, clients are able to communicate with other pre-authorized intermediaries while still receiving a response from the server, despite the "additional" communications.

The security, application, and business logic layers of the RESTful web service can be designed to cooperate across multiple servers to fulfill client requests. The client cannot see these layers.

4. Caching

This type of architecture can be cached, speeding up the processing of some responses in the client's cache or in an intermediary, increasing the response time between client requests.

For example, when entering a page that contains too many images, these can be stored in the cache, so that the next time the user enters the page, the loading speed will be faster.

5. Code on demand

By passing software programming code to the client, REST-style servers can augment or momentarily alter the client's functionality.

Take for example the forms you find on any website. If you fill it out and there’s a mistake, like the wrong phone number, the server detects it and points it out so that the user corrects it.

And what does RESTful mean?

Very simple: it’s the implementation of the REST architecture in your web environment. Or in other words, it’s the REST API in execution.

The RESTful API also involves how the API interacts with other applications and other environments. Also, the responses it receives and the efficiency of its integrations.

But how does a REST API work?

To understand how a REST API works, the first step is to know the HTTP verbs, which are the methods used to send requests and receive responses on the web. The most common HTTP verbs are:

• GET: to request information from a resource.

• POST: to send information to a specific resource.

• PUT: to update the information of a particular resource.

• DELETE: to delete a resource.

A REST API uses these verbs as a starting point to communicate with other applications. All through requests and responses in JSON, and XML, among other formats.

Now, suppose you want to develop an API for your website, in this case, an API to find products for your users. Or even a marketplace or e-commerce. 

In this API, if you’re looking for information about a camera or a computer, you can make a GET request to the REST API, using a URI specific to your computer. The REST API returns the product information in JSON or XML format, which we can use in our application.

In addition, REST APIs often use authentication via access tokens, which allow applications to authenticate with the API before making any requests. 

This helps ensure the security and privacy of data being transmitted between applications.

What is the difference between APIs and REST APIs?

The main difference between an API and a REST API is the way they communicate with each other. 

An API can communicate using any protocol, data format and architecture that suits your needs. On the other hand, a REST API is based on a set of architectural principles that define how it should be designed and function.

In other words, REST is a specific web architecture model.

A REST API follows a set of architectural principles that are based on the web and uses the same standards, such as HTTP and URIs. 

This allows REST APIs to be interoperable and to easily interact with other applications on the web.

Also, REST APIs are often simpler and easier to use than other APIs. All thanks to the principles and standards based on intuitive and globalized usage.

5 Advantages of REST APIs

A REST API offers many advantages over other types of APIs. Some of the main 

Advantages are:

1. Interoperability 

REST APIs are based on the same standards used for the web. Same language, same code and architecture. They are highly interoperable and can easily interact, synchronize and integrate with other applications.

As a result, APIs are part of the entire web environment, from blogs and social networks to CMSs and development platforms.

2. Flexibility

REST APIs can communicate using any data format. In other words, they can be adapted to almost any application on the web regardless of its format, language or architecture.

3. Scalability

REST APIs are highly scalable. They can handle thousands, millions, and billions of data simultaneously without affecting performance.

In other words, they can process huge blocks of information while the two websites, connected through the REST API work seamlessly. 

4. Security

REST APIs typically use authentication via access tokens,

Tokens are much more difficult to crack as they are unique. In addition, they can be supplemented with other authentication methods to double the security standards.

In this way, both security and data privacy are almost impassable to hackers and information gatherers.

5. Ease of use

REST APIs are simpler and easier to use than other APIs.

You can become familiar with the REST API fairly quickly regardless of your level of web development and programming. 

In fact, you'll find it intuitive and easy to use even if you don't have any web development experience, as long as you learn languages like HTML, Python, or JavaScript.

And once you have more experience, its functions, and add-ons will be even easier to use. 

What are the disadvantages of a REST API?

Although REST APIs have many advantages, they also have some disadvantages that you should be aware of, especially if you are looking to specialize in web development. Some of the main disadvantages are:

1. Increased design complexity.

Although they are easier to use, the design of a REST API can be more complex than other APIs, especially if you are not familiar with web architecture. 

The REST API uses architectural principles that you need to be familiar with in order to develop your API.

2. Web connection

All changes to your REST API must be executed on the web and only on the web. It’s impossible to edit the API from your desktop without an internet connection, unlike HTML web files, for example. You must always connect to make the slightest change.

A REST API requires an Internet connection to function, which means it may be less useful in offline environments.

3. Variable performance and flexibility

On the other hand, REST APIs can have slightly lower performance than other APIs, depending on the servers and their internet speed.

And in some cases, a REST API may be less flexible than other APIs because of the architectural principles it must follow. 

In other words, although its architecture is quite versatile and can be synchronized with other applications, the development of this architecture is less flexible.

Despite its unfavorable points, REST APIs are a must-have for web developers and companies worldwide. 

This is the API of choice for millions of companies and development teams, so knowing about it will give you access to countless opportunities. 

At the same time, we recommend you to complement your repertoire of tools with other API models, as well as programming languages. 

You can start with HTML and JavaScript and their different formats, such as Node.JS JSON, and if you want to go a step further, you can delve into Python and more complex languages such as C and C++.

Also, if you want to become a web development specialist, we invite you to check out our trainings and bootcamps.

What does the client request in the RESTful API consist of?

Every request from the client to the interface must contain certain essential elements:

1. Unique number of resources

Using specific resource identifiers, the server recognizes each resource. It usually uses a uniform resource locator or URL to identify resources in REST services. The path to the resource is specified by the URL.

When visiting any web page, a URL is similar to the website address that is entered into the browser. The endpoint of the request, also known as the URL, provides the server with clear instructions about the client's needs.

2. Method

Almost all developers using RESTful APIs choose to use hypertext transfer protocols, better known as HTTP. This method is one of the most effective for informing what the server should do with each resource. It’s composed of 4 common aspects

• GET: Used to access resources at the server's specified URL.

• POST: Used to send data to the server by clients.

• PUT: Used by clients to update resources on the server.

• DELETE: Used by clients to delete resources.

3. HTTP headers

All metadata that is transmitted between the client and the server is contained in the request headers. 

One can say that the request header sets out what the request and response formats are, to provide details on the status of the request.