To see the youtube video where I explain the topic, please click here.
What Are APIs?
An API (Application Programming Interface) is basically a function over the internet, made over HTTP (the protocol that normal web requests use). It allows for certain functionality to happen, where the function exists somewhere on the internet and can be called from anywhere as long it's in the proper format has has correct authentication.
Common examples of API usage is for filling in content any time it's necessary in a website or app, or providing your API users with information from your database or some function to make it easy for them. For example, many times when websites load content (for example, item listings on Amazon), the pages aren't hard coded in HTML to load the details of specific items. Instead, the items exist as resources in a database, and an API is used to speak to that database to fill in HTML of the loaded web page based on a number of factors for the user. Another example is Google providing people access to their Google Maps API so they can use it for their apps or websites.
APIs are very important and get used for basically any website or app that need some special work done (including speaking to a database or doing a special task).
Consuming an API
An API can be called by simply using a URL, much like you'd use in your web browser.
If an API exists on the internet, there are three parts to properly
The URL path, parameters, and request body can all be customized to accept certain information for the request that you wish to make. (For example, for Google Maps API, we may choose to ask the API to give us an address if we give it latitude and longitude coordinates.) The implementation of the API is up to the developer. To see best practices, see this stack overflow question.
HTTP Methods (GET, POST, PUT, DELETE)
These methods get defined when you create your API.
Again, they're not actually part of some code or some magical rule that governs API servers...they're just convention. You could still make a deletion on a GET request, but that'd be considered poor practice. It's still possible.
What an API Returns
There are two things that an API returns after making a request. The first is a response code. There are a bunch of response codes for different situations, and this website does a good job of going over them.
The most important response codes are:
The other thing an API returns is the content that was requested, called the response body. This usually comes in json format, but unpopularly, it may also come in XML format.
Making an API
An API is created writing some functionality in a programming language (typically Java and NodeJS are most popular), and putting that code onto a server that sits there waiting for requests. Pretty simple, right?
There are a few things that you should do if you want to create an API:
Let's Create Our Own API
This blog post was the introduction to a series on APIs! We're going to, from start to finish, create our own APIs using Java and NodeJS, following all the steps along the way.
The next step is to plan an API project and create the Swagger documentation. Click here to see the next article in this series, where we do that.
For the youtube video on the Introduction to APIs, watch it here:
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