At a glance

An application programming interface - or API for short - is the established technical term for a programming or application interface. Such interfaces are usually used to integrate applications at source code level into software systems. In short, two programs communicate with each other via an API. The exchange of information between the software system and the application is usually completely standardized in real time.

Differentiation API vs. UI

An API is clearly distinguished from a UI (User Interface). The user interface serves the human user of an application to exchange data with a program. After entering data in the frontend, the user receives an answer or a result of the program from the backend. In contrast to a user interface, an API does not communicate with a real person, but enables standardized data exchange between the backend of a software and another software.

Classification into four API types

The concept of an API is something abstract and is used in development in many different places. What unites the different forms of APIs is the communication between two non-human "partners". For example, software on a PC can communicate with the hardware via an API, two programs on a PC can communicate with each other, or servers on the Internet can communicate with each other. These different characteristics are briefly described here using the four API types:

• Function-oriented API: The communication of function-oriented APIs is realized by the exchange of functions and function parameters.
• File-oriented API: The file-oriented APIs exchange information using file system calls (open, read, write, or close).
• Object Oriented API: Object-oriented APIs work via so-called interface pointers, which allow greater flexibility.
• Protocol Oriented API: Protocol-oriented APIs can be implemented regardless of operating system or hardware.

Advantages of APIs

There are some advantages to using APIs. One of the most serious advantages is the outsourcing of large software to individual program modules. Thus, individual functions of extensive software can be outsourced into manageable program modules. This outsourcing into fragments of the entire software makes the interface easier to maintain, which in turn leads to less susceptibility to errors. In addition, an API is provided at a central location, but can be used decentrally. This makes APIs particularly interesting for various cloud models that enable users to use services without their own hardware.

Application examples web API

In order to illustrate the sense and purpose of an API, here are some application examples of APIs. At this point the Web-APIs are in focus. An application example for a web-based API is Google Maps, which is part of the big Google cosmos. If the operator of a shop in a shopping street wants to integrate the map service on his website in order to be found by his customers, he does not have to have access to all Google services. By providing the Google Maps API, the store operator can easily use the Google Maps interface for his site, allowing him and his customers to benefit from the map service.

In addition, APIs on the web can also be used to authenticate users. Here, too, Google provides a suitable example: since many users use the services of the provider and have a login with all important user data, this data can also be used for other pages through an API. This can be, for example, an online shop that wants to offer its customers the easiest possible way to authenticate themselves. Thanks to the interface to Google, the shop operator can integrate the Google API into his shop for authentication. The customer saves the creation of a new login for the shop and can identify himself in the shop simply with a click via the Google interface.

ROBIOTIC API as the wire to the network operators

The application examples mentioned are open APIs, i.e. interfaces that are publicly accessible and can be used. In contrast to the open API, there are also closed or private APIs that are not accessible to everyone. These closed APIs can only be used by selected individuals who have previously been granted permission to use them. We at ROBIOTIC use such closed APIs to connect our customers' systems to the systems of the leading network operators via an interface. Here you can find out more about data transmission via mobile radio for your IoT projects that can be used anywhere in the world.