APIs
- Computer Science Department
API stands for Application Programming Interface. It's a set of rules and protocols for building and interacting with software applications. An API defines methods of communication between various software components. It specifies the data format, conventions, and protocols for requests and responses in communication.
APIs allow different software systems to communicate with each other and share data and functionality. They serve as an interface between different software programs and facilitate their interactions, similar to the way the user interface facilitates interaction between humans and computers.
There are several types of APIs:
Web APIs or HTTP APIs or REST APIs: These are designed to communicate with web services and use HTTP methods for interaction. They allow the creation, reading, updating, and deletion of resources, often modeled in JSON or XML format. They are accessible via HTTP protocol and can be used by any client that conforms to the API's structure and rules.
SOAP APIs: SOAP (Simple Object Access Protocol) is a messaging protocol that allows programs running on disparate operating systems to communicate with each other. Unlike REST APIs, which are stateless, SOAP APIs are stateful with specifications for both the request and the response.
Library or Framework APIs: These are a set of classes, functions, and procedures that an application can call to perform specific tasks. For example, the Java API provides a collection of classes, interfaces, and methods for commonly used data structures, operations, and system-level tasks.
Database APIs: These APIs allow communication with a database from a server by using a programming language. These APIs define the correct way for a developer to write a program that requests services from a database. For instance, http://ADO.NET in .NET Framework, JDBC for Java, etc.
Operating System APIs: An Operating System API allows the application to interact with the operating system by using certain system calls. For example, an OS API might allow an application to create a file, start a print job, or open a network connection.
APIs are used for a variety of tasks. They can be used to fetch data from a server, update or delete existing data, run complex queries, upload files, process images, send emails, and much more. They are crucial in microservices architecture where each microservice communicates with others via APIs. They are also heavily used in cloud computing for programmatic access to cloud resources.