First published: December 31, 2021 @ 6:00 pm
Today, APIs are one of the hottest topics in the developer management community. While they are famous as an important part of the software development lifecycle, most developers are unaware of what exactly an API is.
While some people know APIs only as one of the technologies that they use in their daily work, others are completely unfamiliar with them.
This article will attempt to provide a short introduction to the subject, including the main characteristics and types of APIs.
What is an API?
An API can be a library, a web service, or some other software component. The client application may be a desktop application, a mobile application, or any other type of software.
In some cases, an API can also provide some service for the development process itself. For example, the API can manage and track all changes in the source code. We call this a continuous integration.
How does an API work?
We know these functions and data structures as methods or operations in object-oriented programming terminology.
In contrast with the function calls of the C programming language, which involve pointers to memory locations where they store their results, an API always specifies exactly where it stores its results.
They encode this information in the request parameters that clients send when calling an API from their programs or applications. In response, APIs typically return these request parameters as part of their output.
It is also important to note that APIs do not need the association with a single program or application. We can also associate them with multiple and wide ranges of programs or applications.
For example, in many programming languages, you can add new features to the existing code by simply providing new classes that can build new applications. In this case, the new classes are the APIs that make these new features available to the developers.
What are the main characteristics of an API?
There are several important characteristics of an API that we should consider when creating one.
The most important characteristic is the existence of a contract between the client and the server (the service) which defines how these functions and data structures should work in order to call them from other programs or applications.
This contract may include rules for how clients should send requests, what parameters they should send, what values these parameters must contain, etc.
Another important characteristic is that we do all calls to an API through one specific interface (usually a class) which is accessible through public methods.
For example, you cannot call the weather function of the weather server through any other interface except for its own public methods which are located in its Weather class.
This makes it easier for the client to know exactly what function to call and what data to send in order to get the results.
Finally, it is important that the code implementing an API does not do any kind of work itself. This is because other programs or applications that do their own work will call this code.
We should design the interface provided by the API in such a way that all calls to it are transparent and that they store no information from these calls anywhere on the server.
This makes it much easier for other programs or applications to call this API without knowing anything about its internal implementation.
Why do we need an API?
In order to provide a set of functions and data structures that clients can use, an API must provide these functions and data structures in a standard way. An API must make it possible for all clients to access these functions and data structures in the same way.
In the early days of computer programming, programmers have to write a new program from scratch for each different task they wanted to accomplish.
This is because they write each program from scratch for that specific task. In this case, no standards existed that would allow other programs or applications to call this program from their own programs or applications.
This is why they invented APIs. They allow us to use existing code instead of writing the code from scratch for each different kind of task we want to accomplish.
For example, the weather function provided by the weather server does not have any special properties compared with any other function provided by the server.
However, you can call this function through its public methods using a specific set of parameters or request messages which contain all information about how you want to call this function from your own programs or applications.
Another example would be a spreadsheet application that allows you to access its features through an API instead of having its own custom user interface.
This allows you to use your own custom user interface in your programs or applications instead of having to develop a completely new one.
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