What is an API?

API full form is an Application Programming Interface that is a collection of communication protocols and subroutines used by various programs to communicate between them. A programmer can make use of various API tools to make their program easier and simpler. Also, an API facilitates programmers with an efficient way to develop their software programs. Thus Api meaning is when an API helps two programs or applications to communicate with each other by providing them with the necessary tools and functions. It takes the request from the user and sends it to the service provider and then again sends the result generated from the service provider to the desired user.

A developer extensively uses APIs in his software to implement various features by using an API call without writing complex codes for the same. We can create an API for an operating system , database system , hardware system, JavaScript file , or similar object-oriented files. Also, an API is similar to a GUI(Graphical User Interface) with one major difference. Unlike GUIs, an application program interface helps software developers to access web tools while a GUI helps to make a program easier to understand for users.

How do APIs Work?

The working of an API can be clearly explained with a few simple steps. Think of a client-server architecture where the client sends the request via a medium to the server and receives the response through the same medium. An API acts as a communication medium between two programs or systems for functioning. The client is the user/customer (who sends the request), the medium is the application interface programming , and the server is the backend (where the request is accepted and a response is provided). Steps followed in the working of APIs –

• The client initiates the requests via the APIs URI (Uniform Resource Identifier)
• The API makes a call to the server after receiving the request
• Then the server sends the response back to the API with the information
• Finally, the API transfers the data to the client

APIs are considered safe in terms of attacks as it includes authorization credentials and an API gateway to limit access so as to minimize security threats. To provide additional security layers to the data, HTTP headers, query string parameters, or cookies are used.

If we talk about the architectures, API’s architectures are:

• REST (Representational State Transfer)
• SOAP (Simple Object Access Protocol)

Both define a standard communication protocol for the exchange of messages in XML (Extensible Markup Language).

How is an API Different From a Web Application?

An API acts as an interface that allows proper communication between two programs whereas a web application is a network-based resource responsible for completing a single task. Also, it’s important to know that “All web services are APIs, but not all APIs are web”.

The difference between an API and a web application is that API allows two-way communication and web applications are just a way for users to interact through a web browser. A web application may have an API to complete the requests.

Types of APIs

There are three basic forms of API –

1. WEB APIs

A Web API also called Web Services is an extensively used API over the web and can be easily accessed using the HTTP protocols. A Web application programming interface is an open-source interface and can be used by a large number of clients through their phones, tablets, or PCs.

2. LOCAL APIs

In this type of API, the programmers get the local middleware services. TAPI (Telephony Application Programming Interface), and .NET are common examples of Local APIs.

3. PROGRAM APIs

It makes a remote program appear to be local by making use of RPCs (Remote Procedural Calls). SOAP is a well-known example of this type of API.

Few other types of APIs:

• SOAP (SIMPLE OBJECT ACCESS PROTOCOL): It defines messages in XML format used by web applications to communicate with each other.
• REST (Representational State Transfer): It makes use of HTTP to GET, POST, PUT, or DELETE data. It is basically used to take advantage of the existing data.
• JSON-RPC: It uses JSON for data transfer and is a lightweight remote procedural call defining a few data structure types.
• XML-RPC: It is based on XML and uses HTTP for data transfer. This API is widely used to exchange information between two or more networks.

What are REST APIs?

REST stands for Representational State Transfer, and follows the constraints of REST architecture allowing interaction with RESTful web services. It defines a set of functions (GET, PUT, POST, DELETE) that clients use to access server data. The functions used are:

• GET (retrieve a record)
• PUT (update a record)
• POST (create a record)
• DELETE (delete the record)

Its main feature is that REST API is stateless, i.e., the servers do not save clients’ data between requests.

What is a Web API?

Web API Is simply an API for the web. It is an API that can be accessed using the HTTP protocol. It can be built using Java, .nET, etc. It is implemented to extend the functionality of a browser, simplify complex functions, and provide easy syntax to complex code.

The four main types of web APIs are:

• Open API
• Partner API
• Internal API
• Composite API