Functionality of API and their Types
Tags: functionality, apigateway, api, programming
Published: 2023-11-09 10:40:58


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**What is an API?**

Application Programming Interface or API is a set of rules and communication protocols allowing different applications to communicate. They act like a middle layer that processes data transfers between systems, enabling companies to share their application data and functionality with third-party developers, businesses, and internal departments. 

APIs help businesses connect their different applications, saving time and breaking down silos that hinder collaboration and innovation. For developers, API documentation simplifies application integration by providing a communication interface between applications.

**How do APIs work?**

Let’s take a look at third-party payment systems to understand the functionality of APIs. When a user buys a product online, APIs are used to connect to a third-party payment system like PayPal. The API retrieves information via a request that contains a request verb, headers, and sometimes a request body. The API then transfers the request to their external program or web server and waits for a response. Once the server sends the requested information, the API transfers it to the product website. APIs exchange data within the computer or application, making it a seamless connection for the user. 

**Types of APIs**

APIs are categorized into three basic types 

1. WEB APIs (Web Services) are open-source interfaces that can be accessed using HTTP protocols. 
2. LOCAL APIs provide local middleware services, such as TAPI and . NET.
3. PROGRAM APIs use RPCs to make remote programs appear local. SOAP is a common example of this type of API. 

**A few other types of APIs include:**

1. SOAP (SIMPLE OBJECT ACCESS PROTOCOL) defines messages in XML format for web application communication.
2. REST (Representational State Transfer) uses HTTP to GET, POST, PUT, or DELETE data to take advantage of the existing data.
3. JSON-RPC is a lightweight remote procedural call that uses JSON for data transfer.
4. XML-RPC uses XML and HTTP for data transfer and is widely used for exchanging information between networks.
 
**How do APIs enable digital transformation?**

Companies are rapidly transforming digitally to stay competitive and meet the demands of their customers. APIs are a valuable tool for digitizing, connecting, and innovating across products and services. In fact, according to research by Change Healthcare, 90% of executives consider APIs to be crucial to their business. By adopting an API-driven approach, companies can foster growth and innovation. Incorporating APIs into business operations can simplify and speed up go-to-market strategy, improve customer experience, increase operational flexibility and speed, and expand revenue, market, and channel opportunities.

**API Testing**

API testing is essential to ensure that an API functions as expected. It involves analyzing an API function as expected. It involves analyzing an API’s functionality, security, performance, and reliability. The **[testing process](https://copperchips.com/quality-engineering/)** includes sending requests to one or more API endpoints and verifying the response. Business logic, data responses, security, and performance bottlenecks are the main areas of focus during API testing. APIs are critical for exchanging data between applications in [software development](https://copperchips.com/). 

**Types of Testing**

1. Unit Testing
2. Security Testing
3. Functional Testing
4. Integration Testing
5. Performance Testing

**API Testing Tools**

1. JMeter
2. Ping API
3. Apigee
4. vREST
5. Soap UI
6. Postman

**What is an API gateway**

An API Gateway is a tool that helps manage APIs for companies that use a variety of back-end services. It takes care of tasks like user authentication, statistics, and rate management that apply to all API calls. It makes things easier for businesses by handling these common tasks so they don't have to.

**How to create an API**

Developing an API that garners approval from other developers and engenders trust requires considerable diligence and effort. The following five steps are essential for creating a high-quality API design:
 
**Plan the API**

It is imperative to meticulously plan API, with API specifications such as OpenAPI offering a blueprint of the API design. Anticipating different use cases in advance and ensuring that the API adheres to current API development standards is highly recommended. 

**Build the API**

API designers use boilerplate code to prototype APIs. After testing the prototype, developers can personalize it to meet internal specifications. 

**Test the API** 

API testing is as vital as software testing and must be performed to prevent bugs and defects. Utilizing API testing tools can be beneficial in conducting a strength test of API against cyber attacks.

**Document the API** 

API documentation is a guide to help users understand how APIs work and use them effectively. It is especially important for APIs that offer a variety of functions and use cases, as they tend to be more popular in service-oriented architecture.
 
**Market the API**

API marketplaces exist for developers to buy and sell other APIs, similar to Amazon’s retail. Developers can list their API to monetize it.  

**Restrictions of Using APIs**

API is not released as software for download. APIs usually have policies that govern their use and access. Three types of policies are commonly used to govern APIs.: 

**Private:** These APIs are made for a single person or entity, such as a company that has invested resources to build or buy them. 

**Partner:** This policy allows some partners or entities to use APIs for their private use. 

**Public:** These APIs are available to everyone in the market, but you may need to have specific API access from an entity that owns private APIs for their internal use. “Windows API by Microsoft” is one of the examples of a public API. 

**Advantages of APIs** 

APIs offer several benefits to organizations, including increased efficiency, agility, and reliability, which surpass the output produced by human beings. Furthermore, APIs provide developers with a fast and flexible method of delivering services tailored to their specific needs.

APIs facilitate the integration of data between various sites, resulting in a more seamless user experience. Moreover, utilizing APIs eliminates the need for human intervention and allows for more automated results.

Developers often discover new tools and functionality while utilizing APIs, which enhances the overall API exchange experience.

**Disadvantages of APIs**

Cost: API development and implementation can be expensive and require ongoing maintenance and support from developers. 
Security issues: Using APIs can increase the risk of security breaches. The more surface area there is to attack, the higher the risk of attacks. Therefore, security issues are common with APIs. 

**Conclusion**

It's important to have a clear understanding of what an API is, how it works, the different types of APIs, and the testing tools used. Once you have grasped these concepts, you can start implementing them in projects to gain practical experience. It's not enough to just have theoretical knowledge - developers must have a deep understanding of APIs to implement them effectively.