What is a RESTful API?

Is a RESTful API a lazy program or one that initiates a rest state? If you’re interested in the web and how the various technologies behind it work, you will want to know about RESTful API.

What is API?

An API is an Application Programming Interface that can be many things to many programmers. Essentially, API is the middleman that allows you to plug one program into another.

Many programmers and developers will hide their core code to stop others from stealing their hard work. If they want other programs to work with their program, they also have to make some code available to allow that interaction. That’s where APIs come in. A developer can create APIs that allow other programs to interface with their creations and provide extra features and interactions.

An API gets written with a particular structure that gets formatted a certain way so that the resource understands, and it also doesn’t use too many resources. Numerous websites, programs, and platforms use APIs, such as Facebook, YouTube, Google Maps, Android, and iOS. Additionally, the most notable software almost always uses a programming interface. An API is a valuable way of adding features without releasing how your program’s code and structure.

How are APIs used?

If you wanted to build a set of camera filters for a phone, you would use Apple’s or Android’s camera API to utilize their camera’s functions rather than build your own.

The alternative would be to create camera software for each OS, which is a lot of work. Instead, you create an API that can communicate with the existing camera software and then send your filter data to and from it.

APIs can also be used to access system resources, interface with other systems, provide value-add features to browsers, and more. Just remember that an API is a piece of code that talks to other programs, and you should be okay.

Another example of how APIs get used is Google Maps. If you want to add a Google Map to your website, showing your location, you set up a Google Maps API with an HTTP GET query to pull the map from Google.

This way, you get what you want without Google having to do anything or allow access to the internals of its mapping platform.

By using an API, Google Maps servers can satisfy millions of queries in a short period of time without overloading the map server. The API queries get correctly structured to satisfy needs using the fewest resources. The RESTful API ensures nothing can be written to the database and leaves no trace, leaving the map server to move on to the next query.

RESTful API Defined

REST stands for REpresentational State Transfer. A RESTful API is used to transfer data from one resource to a client. As an example, a search engine uses a type of RESTful API.

You enter a search term and the engine queries the servers. The serves transfer the correlating data to your browser for you to use. This is how RESTful API works.

You already know that an API allows external programs to interface with other specific applications. A RESTful API allows an independent program to communicate with a completely separate database, like in the search engine example above.

How RESTful API Works

What makes a RESTful API work is that it is stateless and cacheable. Stateless means the query made by a RESTful API has no impact on the database. Additionally, the query is not (always) logged. Nothing is stored in the database and cannot write to the database. It is essentially a read-only procedure.

Being cacheable means the API client can store the information for future use so it doesn’t have to query the database every single time.

For the web, the API will likely use the HTTP method to process a request. The common HTTP methods are GET, POST, PUT, and DELETE. In the search engine example, the RESTful API would use the HTTP method to GET your search query data from the search engine database in order to display the search results.

Another example would be a Twitter user search. If you put the URL www.twitter.com/realDonaldTrump into a browser, the browser will use HTTP to GET Donald Trump’s data from Twitter and display it to you. As Twitter usernames are unique, the query will return the details to your browser.

The RESTful API is a rather elegant way of sharing information without impacting server performance or giving too much away. This tutorial just scratches the surface of how they work and integrate into the web, but it should give you the basic idea of how RESTful APIs work.