Application Programming Interface
Application Programming Interfaces, known by the acronym API, have shaped our digital environment. Their history begins in post-war England, within the laboratories of Cambridge. Maurice Wilkes and David Wheeler, two little-known pioneers, developed a modular program library for the EDSAC computer. These British researchers stored their creations on punched tapes in a simple metal cabinet, accompanied by a catalog detailing their use. This modest arrangement constitutes the first documented trace of an API.
Wilkes and Wheeler formalized their work in 1951 in the book The Preparation of Programs for an Electronic Digital Computer. This book marks the conceptual birth of standardized interfaces between computer components, well before their current denomination.
The term “API” made its first scientific appearance in 1968 in the work of Ira Cotton and Frank Greatorex. Their paper “Data structures and techniques for remote computer graphics,” presented at an AFIPS conference, described ways to abstract the specifics of graphics peripherals. Fortran programmers then used subroutine calls to free themselves from hardware constraints.
The 1970s saw the concept extend to data systems. In 1974, CJ Date published “The Relational and Network Approaches: Comparison of the Application Programming Interface,” integrating these interfaces into the ANSI/SPARC architecture of database management systems. This scientific contribution considerably broadened their scope of application.
The network computing of the 1980s transformed developers’ needs, who now faced accessing libraries on different machines. APIs evolved to support remote procedure calls. This period saw the birth of interfaces promoting compatibility between disparate platforms.
The Internet revolution of the 1990s pushed APIs toward data exchange between applications via standardized protocols. Carl Malamud proposed in 1990 a definition that has endured through the ages: a coherent set of services made available to a programmer to accomplish specific tasks. This decade laid the groundwork for emerging web services.
The year 2000 was significant with Roy Fielding’s doctoral thesis, Architectural Styles and the Design of Network-based Software Architectures. This work established REST as the reference protocol for communications between connected systems. Also in 2000, Salesforce presented the first modern API at the IDG Demo conference, thus inaugurating a new technological era.
During this decade, online services multiplied. Salesforce, eBay, and Amazon innovated by exploiting HTTP to disseminate machine-readable data, formatted in JSON or XML, via web APIs. From small players to industrial giants, companies massively adopted the model based on the cloud and APIs. Amazon played a pioneering role by requiring that all shared digital resources have an API.
From 2010 onward, the explosion of social networks catalyzed API evolution. Organizations sought cost-effective solutions to create adaptable applications. These interfaces simplified integration with external services such as payment processors or customer relationship systems. The arrival of Kubernetes around 2015 accelerated the transition toward distributed architectures composed of autonomous microservices, each with its own API.
The 2020 health crisis intensified our dependence on web services, multiplying the use of programming interfaces. Their role extended to connected objects and the creation of artificial intelligences. Organizations deployed their applications across different cloud providers, placing APIs at the center of communication between services.
Currently, evolution focuses on two major axes. Security is a priority given the growing vulnerabilities of distributed systems. The zero trust principle is becoming standard, systematically verifying authentication and authorizations, including for internal requests. Rate limiting mechanisms protect against denial-of-service attacks, while observability detects and resolves incidents.
API governance establishes in parallel rules for their design, deployment, and maintenance within organizations. The objective is to guarantee their consistency, security, and scalability in harmony with business strategy.
APIs have revolutionized the way developers create applications, with increasingly sophisticated abstractions. What began as a simple exchange between two computers in a British university laboratory today forms the backbone of 21st century digital systems, particularly in the distributed universe of cloud computing.