What is API? Definition, Types, Functions, and Examples

API stands for Application Programming Interface. It is a set of functions or services that can be utilized by another program to access data or features from the said program.

Several major companies that focus on product integration typically leverage API functions to enhance work efficiency. For instance, Google Maps utilizes APIs to access location data from Google Search.

This enables Google Maps users to view their current location on the map without needing to download location data locally.

If you are curious about this term, the article below will discuss what is API, its functions, types, examples, and API architecture. Therefore, make sure to follow each discussion thoroughly.

What is API (Application Programming Interface)?

In short, the Application Programming Interface (API) allows various applications or programs to interact with each other, expanding functionalities and enabling integration across platforms.

Interestingly, the entire interaction process can occur without sharing the internal implementation details of each program.

If you're still confused, let's delve further into what is API with the following analogy.

The implementation of APIs is widespread, even in programs or applications you frequently use daily, such as the weather detector on your phone.

To provide weather details, the application needs actual data from a third-party service. In this case, the API serves as the interface facilitating communication between the weather forecasting application and the authoritative external service.

However, as a user, you don't need to know how the service collects data, how its database is organized, or other technical details.

Similar to the analogy above, a developer typically doesn't need to understand the workings or technical explanations of a specific application/program but only needs to choose the required API tools.

The Differences Between API and Web Service

Application Programming Interface are often equated with a web service. However, in reality, these two components have significant differences. To understand the distinctions between API and web service, you can refer to the following table:

How Does Application Programming Interface Work?

Once you understand the general concept, it's also important to grasp how this Application Programming Interface operates. 

In general, the functioning of an API involves a series of steps or processes that enable two (or more) applications to communicate with each other. Below for more detailed information:

1. Request

The process begins when an application, known as the client, requests another application, referred to as the service provider, through the Application Programming Interface . 

This request typically contains information such as the type of operation requested (e.g., retrieve data, add data, delete data) and may provide parameters or required data.

2. Processing Request

Upon receiving the request, the API service provider processes it according to their internal rules and logic. 

This process usually involves activities such as retrieving or manipulating data, executing specific operations, or returning specific results.

3. Providing Response

Once processing is complete, the service provider then sends a response back to the client. This response contains the requested operation results, the requested data, or other relevant information. 

Additionally, the response may include status codes to indicate whether the request was successful or unsuccessful.

4. Processing and Forwarding Response

Subsequently, the client receives the response and processes it according to their needs. Processing may involve displaying data to the user, using the data in subsequent operations, or other actions depending on the client application's functionality.

API Architecture

Application Programming Interface is a crucial component in data exchange, closely tied to architectural principles based on its operational methods. 

Based on the tempo and purpose of creation, they are categorized into four main architectures:

1. SOAP (Simple Object Access Protocol)

SOAP APIs primarily transmit data over networks. Generally, SOAP architecture is widely used in internal data transfer processes that require advanced security measures.

2. Websocket

A modern web API using JSON that supports two-way communication, both between applications and between clients and servers.

3. REST (Representational State Transfer)

This API architecture is considered one of the most flexible and widely used among software developers. This API function is to send data or requests from the server to the client with a lightweight and easily operable guideline.

4. RPC (Remote Procedure Calls)

RPC API is one of the simplest architectures, involving strict protocols to ensure minimal errors and efficient calls. 

Despite its strict protocol, RPC still facilitates developers to execute code on the server without being physically present at the same location.

API Function in Software Development

Now that you understand what is API, how it works, and its architecture, it's time to delve into the various API functions in software development. 

• APIs ease the overall development process, particularly in applications classified as super apps, such as e-commerce platforms, online transportation service providers, and many more.
• It simplifies the integration of data from authoritative sources into software, eliminating the need to create breakthroughs.
• Reducing the server workload, consequently minimizing the potential for server downtime.
• It allows developers to isolate and test different parts of applications separately, enabling each component to be tested and updated independently.

API Types 

Overall, Application Programming Interfaces can be categorized into four types based on their usage and architecture. Some widely applied API types include:

1. Partner API

Partner API is designed for specific external parties or business partners. In this context, external parties typically have specific permissions or interests to access specific data or services from the API provider.

API Examples: Company A, having product data, can provide a Partner API to Company B to access and display that product information on Company B's website.

2. Open API

Open API, also known as a public or external API, is a type of programming interface available to the general public. 

This type provides access to specific functionalities or data without requiring special approval. Authentication and authorization levels are typically low.

API Examples: Twitter API allows external developers to create third-party applications that can access tweet data or other API functions easily.

3. Internal API

Internal API is a programming interface built for the internal needs of an organization or company.

This type is usually used to facilitate communication between various internal components without granting access to third parties outside the organization.

API Examples: A large technology company might have an Internal API connecting security services, user management, and other systems internally.

4. Composite API

This type combines or aggregates data from various sources into a single response. This type can be used to create a sequence flow from two or more relevant applications, alleviating server or system workload and process complexities.

API Examples: Combining data from different sources to create a unified response for a specific application flow.

Endpoint in Application Programming Interface?

An API endpoint is the URL used to access or interact with an API. In the context of software development, this endpoint serves as a specific digital location where requests can be sent, and responses can be received.

Each API endpoint typically represents specific functionality or services that developers or clients can access. Here are some key points related to API endpoints:

• Unique Address: Each endpoint has a unique address indicating the specific location where certain services or data can be accessed. Example: https://api.example.com/products/123.
• HTTP Methods: This endpoint is usually associated with specific HTTP methods such as GET, POST, PUT, or DELETE. These methods determine the action to be taken on the resource related to the endpoint.
• Authentication and Security: They enhance system resilience against attacks, making steps like authentication (identity verification) and authorization (determining access rights) crucial.

That concludes the explanation of what an API is, its functions, and how it works, along with explanations of each architecture in the software development process.

Application Programming Interface plays a crucial role in supporting interaction and integration between various applications and services. 

By providing standardized rules and protocols, it enables developers to build complex applications by combining and leveraging services from various sources.

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