APIs are increasingly present on the web today, and are used every day in computer systems – even if we don’t see it. When you compare the prices of your plane tickets, look at the menu of a restaurant online or look at the weather on your smartphone, you use an API.
But what do these three letters really mean?
What is an API?
An Application Programming Interface is a set of functions, data types and constants, available on a software library. An API exposes, makes certain data or features accessible. It can be public and therefore accessible to all, or private. When it is private, it has a key, “API key” that allows its user to identify itself as having the right to access its information.
TheREST “Representational State Transfer” API is now the most widely used type of API. REST is a type of architecture used for APIs that centralize shared services. TheREST API is designed to be naturally flexible, and must be “stateless,” meaning the server has no information about the customer’s status between requests. Each application to the API is strictly independent.
What's the use of an API?
An API allows a data source and an application to communicate with each other. This concept of an application programming interface makes it easier for developers to work. Developers in charge of the application development project can use an existing API, developed and programmed by others and thus exploit it in the context of new applications or features, without having to redevelop the source of the information. It gives them an interface that gives them access to the features of another program.
As you can see, the API is the intermediary that allows two fully independent computer systems to interact with each other, automatically, without human intervention.
Why use apIs?
TheAPI has many advantages such as saving time generated by using it. Indeed, this tool facilitates the work of developers who increase their efficiency by recovering a program or a program brick developed upstream. The goal is to exploit them within their own programs and features. In addition, theAPI is very practical because it uses a universal language. When transmitting data from one system to another, theAPI does not need to be “translated” into the appropriate language, however different it may be. Agnostic language, also called neutral language, is called its greatest strength.
What steps are needed to create an API?
Let’s take the example of an API needed to create a movie ticket booking app. The purpose of this app is to display:
- movies on view
- Proposed sessions
- The number of places left, etc.
The first step is to organize the data, and to define the major entities of the project, that is, its resources.
In this example, the resources are:
As a result, the relationship between these resources must be established.
- a director can be associated with several films
- a film is associated with a director
- a room can broadcast several sessions
- a film can be shown in multiple cinemas
- a film can be shown over several screenings
- a movie can have multiple fares
Once the links are established, it is necessary to define the possible actions for each resource. And… The API is created!
To better understand how it is then used, let’s talk about the application/API relationship.
How do apps consume APIs?
The relationship between the application, the “customer” and the API is a two-way exchange. The app initially uses an API to retrieve, delete or add specific information. TheAPI,upon receipt of this request, analyzes the criteria submitted to it and searches for the information. Once the search is complete, theAPI sends a response to the app via a JSONfile, with its response always accompanied by a status code indicating whether the action was done, or not.
In conclusion, you will understand, APIs are now indispensable in the development of digital applications, and have many advantages that we enjoy on a daily basis.
They save developers considerable time and make their work easier by making information available to them publicly or privately.
In addition, they affect their efficiency at work by rapidly implementing new features, reprogramming, adding a function, etc.
They allow for better interoperability between different systems programmed in different languages.
Finally, the strength of APIs lies in the infinite number of implementation possibilities:
- public list of convenience stores
- transport schedules
- price comparison
- online booking sites
All these implementations are all improvements for users of digital tools.