What does Application Programming Interface (API) Mean?
APIs are applications that enable efficient and uncomplicated communication between products and services. They are a set of definitions and protocols that tell systems how to react and what information to retrieve when a particular request is made. To understand how APIs work, it is vital to know the standard vocabulary used to describe their architecture.
- Client – refers to the application that sends the request
- Server – refers to the application that answers that request.
- API call / API request – refers to the messages that clients send to request a service or information from a server.
In a world defined by connectivity, efficient communication is critical.
APIs can be considered contracts between two parties that stipulate how the server reacts when the client sends a request in a particular form. Since the communication terms are clearly defined, the client does not need to know how the server is built to formulate the request. Similarly, the server does not need to understand the client’s internal functioning to ensure that the client can correctly process its answer.
Why are APIs so popular? APIs have gained widespread use because they are incredibly useful in simplifying communication. In a world defined by connectivity, efficient communication is critical. Since API requests always return a predictable answer, APIs are a secure way of sharing data while maintaining control of the assets. APIs’ success also lies in the fact that they simplify the complex internal functioning of systems by abstracting them into only the necessary terms. To enable the efficient development of APIs, different protocols have been invented that standardize how communication among systems occurs.
API technology has been around for a while. Its appearance can be traced back to one of the first computers, the EDSAC, during the 1940s. The EDSAC was equipped with a library catalog with notes or protocols on how to incorporate each subroutine into the program. This library catalog would now be considered an API. The term appeared for the first time in the 1968 paper Data structures and techniques for remote computer graphics.
The start of the new century and the dawn of the internet took the implementation of APIs to the next level. The internet brought the need to handle remote procedural calls, so the first web APIs were born. In the early 2000s, three key enterprises started using APIs for their services:
- February 2000: Salesforce presented its API for its automation services
- November 2000: eBay launched its eBay API and its Developers Program.
- July 2002: Amazon opened its Amazon Web Services to allow private people to integrate Amazon content into their websites.
Nowadays, APIs keep revolutionizing the way applications and systems work. API technology is one of the fuels behind the revolution of cloud-based technology. Cloud applications work under the principle of collaboration. Companies outsource their infrastructure, platform, and software needs and combine ready-made implementations to personalize them. This collaborative approach would be unthinkable without efficient ways of communication between systems.
Types of Protocol Specifications for APIs
SOAP APIs (Simple Object Access Protocol)
This XLM-based protocol has played a central role in implementing web services. It uses application layer protocols, notably the HTTP (Hypertext Transfer Protocol), that are installed in almost all operative systems.
RCP APIs (Remote Procedure Calls)
This type of protocol focuses on the implementation of distributed applications. They are designed to run remote workloads while making the call work as a local procedure.
This protocol has the peculiarity of enabling two-way communication and interaction between client and server. For example, the server can send data or content to a client without waiting for a request. Their two-way communication brings higher efficiency to the process.
REST APIs (Representational State Transfer)
REST APIs also use HTTP for the requests and transfer of data. One of the main features of REST APIs is their statelessness. Statelessness means that the server does not save any data from the requests made by the client, so their state does not change.
Types of APIs according to their use
Private APIs are used as internal tools in an enterprise to connect systems and transfer data within a company.
Public APIs are open for anyone to use. However, their usage might imply fees or require authorization.
Partner APIs are used in B2B applications and are accessible only with corresponding authorization.
Composite APIs integrate different APIs to enable handling complex processes.
API endpoints are the points in the system where information is sent or received. They receive special attention because, being the final points of the system, they are vulnerable to attack. Moreover, API endpoints can be responsible for causing bottlenecks when they involve high-traffic processes. Therefore, constant monitoring of API endpoints is recommended.
Web APIs allow the exchange of information between a web server and a web browser. Nowadays, most web APIs work under the framework of REST APIs.
An API gateway is a tool that helps manage, aggregate, and correctly fulfill a series of API calls. It is a gateway between the client and a collection of backend services. It helps deal with the complexity that real-life applications have. When a request enters, the API gateway will break it into different modules that the system can handle individually.
API integrations are processes that ensure the seamless automatization of API requests. API integrations are handy because they eliminate the need for human intervention.
Authentication tokens are ways in which the system checks the identity of the user and whether they have the use to request the type of API call that they want to access. Authentication tokens are a standard way of ensuring the security of the system.
API Keys are another security measure implemented in the context of APIs. They are also used for verifying the application or program making the request.
API management is a series of tasks related to the creation and maintenance of an API. API management includes controlling access, ensuring security, maintaining performance, reporting, and if applicable, monetarization.
An API marketplace is a platform specialized in offering APIs. Like in other marketplaces, in API marketplaces, people can upload their products (the APIs) for consumers to find and use (some of them for a fee).