An API (Applications Programming Interface) is a software intermediary that allows two applications to talk to each other. Beginners who are just starting to develop or even work with APIs should first learn how to use an API from this RapidAPI tutorial and pay attention to the technical details of how an API communicates to services. In this article, we will talk about the technical details of how APIs work. 

Types of APIs

APIs are classified into four different types, RESTful, SOAP, JavaScript, and XML-RCP. RESTful APIs are the most common types used today.

RESTful APIs: These are APIs that use HTTP requests to GET, PUT, POST, and DELETE data.

SOAP APIs: SOAP stands for Simple Object Access Protocol. These are APIs that exchange data in the form of an XML file.

XML-RCP APIs: These are APIs that are called using XML to return XML. However, they are not common today since they were developed further to become SOAP.

JavaScript APIs: These are APIs that are only used with JavaScript and mostly by web developers. They are accessed only by JavaScript.

How do APIs Communicate?

APIs communicate with other applications through the use of the underlying HTTP protocol. HTTP is HyperText Transfer Protocol and is widely used on the internet. The most basic version of making an HTTP request happens when you open a web page on your browser. In the same way, APIs use the HTTP protocol to communicate with other applications. For example, if I have an API called My API that wants to access Twitter features, the API will send an HTTP request to the Twitter servers. It will specify the Twitter feature that it would like to access such as Tweets, in the HTTP request.

HTTP Request Methods

There are four major HTTP request methods used by APIs. They include;

PUT: This request method edits existing data.

GET: A method to fetch data.

POST: This method adds new data.

DELETE: A method to delete data.

After my API above has sent instructions to Twitter, of course using one of the methods above, Twitter servers will then process my request. Twitter will process the instructions and return the data I requested. However, you have to make sure that you have given valid inputs for Twitter to return any data. Unfortunately, the format of the data in the request and how to make the request is not uniform between programming languages. 

API Authentication

APIs ask for authentication when a person is using them. This is important because it offers protection against abuse by users. For example, an API user might make thousands of calls in a minute making the API unstable and slow for all other users. APIs also require authentication from users of the application being accessed. This happens when a user is allowing access to their personal data. For example, in my API above, we asked for permission to access the tweets of a Twitter account. APIs use different types of authentication;

  1. HTTP Basic Access Authentication: This is a basic form of authentication that requires only a username and a password.
  2. OAuth 1.0: This form of authentication works with a unique string that is assigned to a single user. This string is called a token.
  3. OAuth 2.0: This is basically an upgrade to OAuth 1.0, but it is more secure and allows interoperability between different services. It is less complex and uses well known and tested standards.

That basically sums up the technical details of how APIs work for a beginner. With this knowledge, a beginner is now comfortable to dig deeper into APIs with confidence.

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