What are APIs ?

APIs, or Application Programming Interfaces, are tools that allow two software programs to communicate with each other by following a set of rules and protocols. Think of them as bridges between different systems. For instance, when you use a weather app on your phone, it retrieves data from the weather department’s database via APIs to give you daily forecasts.

What does API stand for ?

API stands for Application Programming Interface. In this context, "Application" refers to any software with a particular function, and "Interface" is the way in which two programs interact. This interaction is essentially a contract that defines how they send requests and receive responses.

Workings of APIs

APIs follow a client-server architecture. The client, or the requesting application, asks for data, while the server, the provider of that data, responds. For example, in the case of the weather app, the app on your phone is the client, and the weather department's database is the server.

There are four different ways that APIs can work.

Soap APIs
These use the Simple Object Access Protocol, where client-server communication happens via XML. Although it's older and less flexible, it was widely used in the past.

RPC APIs
RPC stands for Remote Procedure Call. In these APIs, the client asks the server to execute a specific function, and the server returns the result.

WebSocket APIs
These are more modern and allow real-time, two-way communication using JSON objects. This makes them more efficient than some older types, like REST, as they allow servers to send messages to clients without waiting for a request.

REST APIs
REST, or Representational State Transfer, is the most commonly used API type today. It allows clients to send data to a server using standard HTTP methods like GET, POST, PUT, and DELETE. The server processes the request and sends back the data. A key feature of REST APIs is statelessness, meaning each request from the client is treated independently, without the server storing any previous client data.

Why use APIs ?

Integration
APIs simplify the process of connecting new software with existing systems. Instead of building everything from scratch, developers can rely on APIs to reuse existing functionality, speeding up development.

Innovation
APIs allow for rapid innovation by enabling businesses to implement new features and services without rewriting entire systems. By making updates at the API level, companies can respond to industry changes faster.

Expansion
APIs also allow businesses to collaborate with partners more easily, sharing services and inventory across systems.

Ease of maintenance
Since APIs serve as intermediaries, any internal changes in one system don’t affect the other system. This separation makes it easier to update and maintain each system independently.

Different types of APIs

Private
These are restricted to internal use within an organization. They allow different systems and data within the company to communicate but aren't accessible to the public.
Public
Public APIs are open for anyone to use. Some may require authorization or come with costs, but they are generally available to developers outside the organization..
Partner
Partner APIs are accessible only to select external developers. They help facilitate business-to-business collaborations by allowing controlled access to certain services or data.
Composite
These APIs combine multiple APIs to handle more complex functions or tasks. They are useful when systems need to perform multiple operations in a single request.

What are API endpoints ?

API endpoints are the specific touchpoints where communication between systems occurs. These include server URLs, services, and other digital locations where data is exchanged. API endpoints play a crucial role for businesses for two primary reasons:

Security
Endpoints can be vulnerable to attacks, making them a critical point for potential breaches. Monitoring API activity is essential to detect and prevent misuse.
Performance
High-traffic API endpoints can become bottlenecks, slowing down system performance. Proper optimization and monitoring help avoid these issues.

How to secure APIs ?

Securing APIs is essential to protect against unauthorized access and misuse. Two key methods to secure REST APIs are::

Authentication tokens
These tokens are used to verify the identity of the user making the API request, ensuring they have permission to access the service. For instance, when you log into an email service, authentication tokens verify your identity and grant you secure access.s.

API keys
API keys identify and authorize the application making the request. Although not as secure as tokens, API keys provide a way to monitor usage and track how often the API is accessed. You may have noticed a long string of characters in your browser URL—this is often an API key used for internal API calls.

How to create an API ?

Creating a well-designed API that developers will want to use involves careful planning and execution. Here are five key steps to building a reliable API:
1. Plan the API
Start by outlining the API's functionality and design using specifications like OpenAPI. Consider different use cases early in the process to ensure it meets current development standards.
2. Build the API
Developers create a prototype using boilerplate code to test the core functionality. Once it's verified, the API is customized to meet specific internal needs.
3. Test the API
Testing is crucial to identify bugs and ensure security. Tools can be used to simulate cyberattacks and assess performance under various conditions.
4. Document the API
While APIs can be self-explanatory, thorough documentation helps developers understand how to use them effectively. APIs with well-written documentation tend to be more widely adopted.
5. Market the API
APIs can be listed in API marketplaces, where developers can discover, purchase, and sell APIs. Monetizing an API is possible through these platforms, similar to how retail marketplaces work.

What is API testing?

API testing focuses on validating the functionality, performance, and security of the API. Common strategies include:

• Sending multiple requests to API endpoints to assess performance under load.

• Writing unit tests to check business logic and ensure accurate data handling.

• Conducting security tests to simulate attacks and identify vulnerabilities.

How to use an API?

To integrate and use an API, follow these steps:

• Register with the API provider and receive an API key, which is necessary for making requests.

• Use an API client to structure requests easily, including your API key for authentication. If you don’t have a client, you can manually craft the request using documentation and execute it in a browser.

• Once familiar with the API syntax and structure, you can implement it directly into your code, integrating it with your application’s features.