A Beginner's Guide To Understand Application Programming Interface.
Tags: webdev, beginners, api, codenewbie
Published: 2023-09-06 16:32:05

In today's digital age, we always hear about application programming interface or API's in short. What exactly are API's and why are they important in the world of technology? They play a fundamental role in modern software development and the digital services we use daily. In this guide we will demystify API's, explain what they are, how they work and why they matter.

### Table of contents
- [What is an application programming interface](#defination)

- [How an API works](#works)

- [Types of API's](#types)

- [Real world examples of API's](#examples)

- [Advantages of API's](#advantages)

- [Disadvantages of API's](#disadvantages)

- [Conclusion](#conclusion)


## What is an application programming interface <a name="defination"></a>
An application programming interface is a set of rules and protocols that allow different software applications to communicate and interact with each other. It serves as a bridge between two separate software systems enabling them to exchange data and function properly.

## How an API works <a name="works"></a>
**Initialization-** The API provider creates and publishes the API along with docs that describe how to use it.

**Request-** A developer initiates communication by sending a request to a specific endpoint of the API. This request typically includes the following components;

- **endpoint-** The URL that represents the specific resources the developer wants to access.

- **HTTP methods-** specifies the type of action to be performed on the resource such as get, post, put and delete.

- **headers-** contain more information about the request.

- **parameters-** additional data that is needed for the request often passed as query parameters in the URL or as part of the request body.

**Authentication and Authorization-** some API's require authentication to ensure that only authorized users or applications can access their resources. It is typically done using API keys, OAuth tokens and so on. It helps to check the credentials provided in the request to determine if the requester has the necessary permissions.

**Server processing-** the server processes the request based on the information provided which includes understanding the request methods, headers and parameters as well as ensuring proper authentication and authorization if required.

**Response-** after processing the request the server generates a response which includes;

- **data-** the requested data often in a structured format like JSON.

- **HTTP status code-** a code that indicates the outcome of the request eg; 200 for success, 404 for not found and 500 for server error.

- **headers-** additional information about the response such as content type and length.

**Client handling-** the client receives the response from the server and processes it according to the information provided which may involve displaying the retrieved data to the user.

## Types of API's <a name="types"></a>
### Ownership
**Open API's-** they are publicly available to developers with minimal restrictions. They may require registration, use an API key or OAuth tokens. They focus on external users to access data or services.

**Internal API's-** they are designed for internal use within an organization and are hidden from the outside world.

**Partner API's-** they are exposed to business partners and are not publicly available and need specific entitlement to access them.

**Composite API's-** combines different data and services API's. You can use them if you need data from various applications or data sources.

### Architecture
**Representational state transfer(R.E.S.T)-** it is a widely used architectural style that uses standard HTTP methods to interact with resources identified by URLs. REST messages are typically simpler and use lightweight data formats like JSON, XML, YAML, plain text or HTML for data exchange. However, REST does not prescribe a specific data format. REST APIs follow a stateless communication model, meaning each request from a client to a server must contain all the information needed to understand and process the request. REST is more lightweight and is commonly used for public APIs, web services, and mobile applications. It's well-suited for scenarios where simplicity, scalability, and ease of use are important.

### Protocol
**Simple object access protocol(S.O.A.P)-** SOAP is a protocol for exchanging structured information in the implementation of web services. It means that it has a defined set of rules and standards for structuring messages. It specifies how data should be formatted, transmitted, and processed. SOAP messages are typically formatted as XML documents. These XML messages have a specific structure with an envelope, header, and body. SOAP is inherently stateful, meaning it can support complex transactions and operations. It includes features like message sequencing and guaranteed message delivery, which make it suitable for applications that require strong reliability and consistency.  SOAP is often used in enterprise-level applications, web services that require strong security and transaction support.

### System
**Database API's-** They enable communication between an application and a database managment system.

**Web API's-** are API's that deliver requests from web applications and responses from servers using Hypertext Transfer Protocol.

## Real world examples of API's <a name="examples"></a>
**Weather Data-** Weather services like OpenWeatherMap have APIs that developers can use to fetch current weather conditions and forecasts for specific locations.

**Maps and location services-** Google Maps offer APIs that developers use to embed interactive maps and location-based features into their apps.

**Social Media-** Apps like Facebook, Twitter, and Instagram offer APIs that allow developers to integrate their platforms into other apps. For instance, you can log into a website using your Facebook credentials.

**Payment processing-** PayPal and Stripe provides APIs that enable businesses to accept online payments and manage their financial transactions securely.

**News and content-** News outlets like The New York Times offer APIs to access their articles and media content for integration into news apps and websites.

## Advantages of API's <a name="advantages"></a>
**Security-** APIs provide a controlled and secure way to access data and functionality. Authentication, authorization, and rate limiting can be implemented at the API level to protect sensitive information and resources.

**Real-Time updates-** Many APIs offer real-time data and updates, ensuring that applications have access to the most current information.

**Analytics and Insights-** APIs often come with built-in analytics tools that allow developers and businesses to monitor how their services are used. This data can be used to make informed decisions and optimize offerings.

## Disadvantages of API's <a name="disadvantages"></a>
**Latency and performance-**  The performance of your application may be affected by the latency introduced by external API calls. Slow or unreliable APIs can lead to a poor user experience.

**Rate limits-** Many APIs impose rate limits on the number of requests you can make within a specific time frame. This can be a limitation if your application requires frequent or high-volume access to the API.

**Costs-** Some APIs are not free, and their usage can incur costs, which can become significant if your application relies heavily on them. Pricing models for APIs vary, and it's essential to understand the pricing structure before integrating them into your application.

### Conclusion <a name="conclusion"></a>
In essence, APIs serve as intermediaries that enable different software components to collaborate and share data, functionalities, or services seamlessly. They allow developers to focus on building innovative applications without needing to understand all the intricacies of the systems they are connecting to.