What are APIs and why are they important?

Toon Vanhoutte, architect at Noest will tell us more about APIs. What are they, what are they for and why are they so important? Toon explains it all.

An API, short for Application Programming Interface, is actually the user interface for the processes that you want to connect and integrate with an application in an automatic way. You can compare it to a restaurant where there are several chefs in the kitchen: one is responsible for the main course, the other for the desserts, etc. As a customer, you don't just step into the kitchen to order your dish from each chef individually. You order from the waiter, the API, who relays your message to the kitchen. The waiter also has a menu, which is the data contract, which states what functionality the API is going to provide. That way, with your API and your data contract, you can communicate smoothly and easily with the kitchen, without having to know the internal kitchen. So the big advantage of APIs is that you introduce a layer of abstraction.

Uber and Airbnb

We live in a world where data needs to be available anytime, anywhere. Typically, many companies put a lot of different types of connections directly on the application. But if you ever want to make a change to that application, it doesn't work anymore because then you have a negative impact on all the applications, teams and sometimes even external parties that depend on that data. If you make your data available through an API, that is the only medium through which you can access that data or that functionality. So you only have to support the front door and you can close the rest.

This of course has the great advantage that you can change the architecture or technology of your application without impacting all the people and processes that are connected to your application. This has the added asset that you can have teams, applications and even companies connect to each other, but with enough abstraction you can make changes and modifications independently. This gives you consistency across companies and APIs and you can even start building partnerships.

This is one of the most important keys to the success of APIs. Today, everything is connected in the public internet and so companies have also managed to build a nice business model based on APIs. Classic examples are Uber and Airbnb: the largest cab company in the world does not have cabs and the fastest growing company in the tourism sector does not have hotel rooms. They did develop a digital business model based primarily on APIs.

Inside-out vs. outside-in

APIs have been around for a while but have experienced a major boost, especially in the last 5 years. This coincided with the switch from companies with 1 or 2 applications - which include all functionalities - to a 'best of breed' approach where you look as a company at which application you can best use for which domain. But then, of course, that data has to be exchanged between all the systems, and so the need arose for standardization and integration of all those connections.

When you start an API story, it is also important not to let it start from a technical point of view but rather from the perspective of functionality. So design your APIs not inside-out, starting from your application, but outside-in, namely from the perspective of the end user and how we can make her or his life easier.

Avoiding pitfalls

Installing APIs obviously also has some pitfalls that can certainly be avoided. The most important one is security. Within the safe confines of your firewall, you are quite comfortable but once you start connecting your applications to the public internet, appropriate security must be provided and companies sometimes forget that. That is why it is very useful to install an API management solution, not only to ensure security but also for other important issues such as onboarding, performance and error management. The API management solution has a central view on all the APIs and acts as a watchdog for all the preconditions.

Before you start with APIs, it's important to take a step back and map out your business. Determine your priorities and decide where APIs can be valuable. And then start thinking outside-in: how can we make our most important business domains available to both external parties and internal teams in a user-friendly and simple way. So first take the temperature before you jump in the deep end.