Software or its components do not require a graphical user interface to communicate with each other. Programs use machine-readable interfaces or APIs to exchange information and functionalities. API stands for Application Programming Interface. This article will define APIs and describe how they operate.
What is an API Interface?
Two applications can communicate with each other without user involvement through a software interface called an Application Programming Interface (API). An API is a collection of computer functions and procedures. It is executable software that allows two different software programs to exchange data and interact. APIs enable interaction between products or services without requiring an understanding of how these connections work.
How Do Online API Interfaces Work?
A typical way to describe API operation is through request-response communication between client and server. Any front-end application involving user interaction constitutes the client, while the server handles database operations and backend logic. The API acts as an intermediary layer that facilitates data requests and responses between client and server.
What is API Documentation?
API documentation serves as a reference manual that guides users on API implementation. Designed for human readability—typically by developers—well-crafted, comprehensive, and user-friendly documentation is crucial for ensuring positive developer experiences (DX), which significantly enhances API adoption success.
What is an API Specification?
While often used interchangeably, “API definition” and “API specification” are distinct concepts. An API specification provides detailed understanding of API behavior and relationships with other APIs, explaining operational mechanisms and potential outcomes. The OpenAPI Specification offers an excellent example, with GitHub’s OpenAPI documentation exemplifying how specifications describe API capabilities and expected results.
Why Do We Need APIs?
Key reasons for using APIs include:
- As denoted by the acronym API (Application Programming Interface), they enable data sharing and communication between disparate software systems.
- Facilitate efficient integration of content across websites and applications.
- Provide adaptable access to application components, enhancing information and service delivery.
- Enable automated content generation and publication.
- Allow customization of frequently accessed materials and services for users and businesses.
- Support software evolution by anticipating future changes.
Key API Features:
- Delivers valuable services (data, functionalities, audience access)
- Facilitates business model planning
- Promotes rapid adoption, adaptability, and simplicity
- Enables measurement and management
- Provides robust developer support
API Types:
- Open APIs: Publicly accessible without restrictions (e.g., Google’s OAuth API), also called Public APIs.
- Partner APIs: Require specific authorization/licenses for access.
- Internal APIs: Private interfaces developed for organizational internal systems to enhance team productivity.
- Composite APIs: Combine multiple data and service APIs.
API Communication Levels:
- High-Level APIs:
- Typically REST-based with developer-friendly abstractions
- Focus on executing specific functions
- Low-Level APIs:
- Offer granular control with lower abstraction levels
- Enable detailed hardware or application module operations
Summary
- API (Application Programming Interface) enables data exchange between software programs.
- APIs support business model planning and exist in five primary forms:
1) Open API
2) Partner API
3) Internal API
4) Low-Level API
5) High-Level API - Web APIs can be implemented through web servers/browsers, categorized as:
- Client-side APIs
- Server-side APIs
- Common API testing tools include: Ping API, vRest, and Postman.