What is an API?
An API (Application Programming Interface) is a special protocol that facilitates the interaction of computer programs, allowing the functions of one application to be used inside another. This development was created to make programmers’ work easier. Developers can now use the capabilities of various applications without having to consider the type of code they use or how each one processes requests.
An API is a set of classes, functions, procedures, and standards through which apps can effectively interact with one another. Developers use this mechanism to create a wide variety of systems.
APIs are also universally used to allow programs and applications to interact with operating systems and websites. If an API were to be disabled, then nearly every service on the Internet and most computer programs would stop working.
What types of API are there?
APIs are classified by their architecture and scope. Here are the types based on architecture:
- SOAP API - Simple Object Access Protocol, meaning a simple protocol for accessing objects. The client and server exchange messages using XML. This is a less flexible API that was used a lot in the past but has become less popular today.
- RPC API − These APIs are named after the remote procedure call system. The client executes a function (or procedure) on the server, and the server sends the result back to the client.
- Websocket API is another modern web API development that uses JSON objects to transfer data. The WebSocket API supports two-way communication between client applications and the server. The server can send callback messages to connected clients.
- REST APIs are the most popular and flexible APIs on the web today. The client sends requests to the server as data. The server uses this client input to run internal functions and returns the output back to the client.
APIs are classified by scope into the following types:
- Private APIs are internal APIs of organizations that are used only to connect systems and data within a business.
- Public APIs are open APIs that can be used by anyone. There may be some authorization and cost associated with these API types.
- Partner APIs are only accessible to authorized third-party developers to facilitate partnerships between enterprises.
- Composite APIs combine two or more different APIs to solve complex system requirements or behaviors.
What is an API used for?
When a user visits any page on the Internet, they are interacting with the API of a remote server. This is the part of the server that receives requests and sends responses. The API also allows the user to perform various actions without leaving the application. Most modern products use at least a few APIs offered by third-party developers to accomplish this. Companies also develop their own APIs and sell them as a finished product.
An API allows developers to:
- simplify and speed up the release of new products thanks to ready-made APIs for standard functions
- make development more secure by bringing a number of functions into a separate application where they are then hidden
- simplify the process of establishing links between various services and programs
- save money by not having to develop each software solution from scratch
In addition, APIs make programs more reliable. Developers of new software don’t need to understand the logic of low-level functions and their implementation. Programs constantly perform hundreds of internal tasks without the user noticing and without harming each other.
Using an API can also be quite profitable. For example, services that provide information from weather towers charge for each request for up-to-date weather if their API is used in third-party applications. Other companies could follow this same model when providing their services.
How does an API work?
The architecture of an API is usually best explained from a client-server perspective. The application that sends the request is called the client, and the application that sends the response is called the server. A programmer shouldn’t have to learn the internal mechanisms of this programming interface, as simply uniting the applications into a single system would be enough.
There are numerous ways to interact using an API, from native protocols to standard formats. Requests and returns in formats like HTTP, XML, JSON are often used in settings and for receiving static data. There are three main methods for interacting with an API:
- A process that a program can execute using an API.
- Data that must be transferred to the interface for it to perform its function.
- The data that the program will receive as output after working with the API.
Processing and issuing transmitted data is carried out through a set of hidden functions which use encapsulation (concealing the state of an object from direct external access).
Examples of APIs
There are hundreds of APIs for financial systems, social messaging, payments, e-commerce, cryptocurrencies, and more. The fastest growing API segment deals with the exchange and analysis of data in various applications. Some API examples:
- Quick registration in apps using social media accounts. A special API protocol in social networks like Facebook, Twitter and others give users the opportunity to gain simplified access to the company's products by authorizing their account through quick registration on the site.
- Google. This system uses an API to grant access to developers of various applications and gives them the ability to integrate information across different services. For example, you can find and watch a video from the YouTube platform right in the app.
- Weather Underground, which is owned by IBM, sells access to its weather data API. This information is used by weather applications and services.
- An example of an API in online advertising is an app that uses Google Adwords. To set up and more effectively manage advertising campaigns, special modules are created for improved search engine optimization parameters through information interaction.
- Payment processing in apps and online stores also works through an API. Clicking the “Pay” button transfers the user to the payment system’s resource.