What is an API?

API means Application Programming Interface.

It enables communication and data exchange between two separate software systems.

A software system implementing an API contains functions/sub-routines which can be executed by another software system.

API is 3-dimensional Architecture:

All web services are API’s.

All webservices need internet. But without Internet also API’s Work.

If API performed services through internet is called Webservice API’s.

API’s performed services without internet is called API’s.

What is Web Service?

Web service – Service available over the web.

Enables communication between application over the web.

Provides a standard protocol/format for communication.

Why we use it?

Platform independent communication – using web services two different applications (implementation) can talk to each other and exchange data/information.

Example: In restaurant customer order the food.by ordering he is sending request. His food prepared by chef in the kitchen. How the customer request will reach to the kitchen? Here the Waiter will Receive the customer Request and send that request to the kitchen. Once Food is ready then the waiter will get food from the kitchen and serves to the Customer.

In this example

Client is a Customer, Kitchen is Server, waiter act as an API.

Client sends the request to API and API send the request to server. server process the data, and Respond to the API through delivering requested data. Client will receive the data through API.

API is depending on totally two components. Request and Response.

API is part of our day-to-day life these days. Now a days all applications using API. We have thirty or more tools available to perform this API in the market. The most popular tools are SOAP UI, REST API, Postman. SOAP UI is very older technology. Rest API is recently coming into the market from fast 6 years.it is widely popular than SOAP UI.

These two have differences in Architecture level not in the point of user level. Internally these two webservices use internet. If we need to communicate through internet, we need to use protocol called HTTP.

HTTP: Hyper Text Transfer Protocol

HTTPS: Hyper Text Transfer Protocol System.

Using these two protocols we communicate through Internet.

Let’s see what are the differences between SOAP UI PROTOCOL AND REST API PROTOCOL.

SOPA -Simple Object Access protocol.

· Internally HTTP Protocol used by SOAP UI.

· we POST (send) request in SOAP UI and get response.

· This request and response are only in XML format in the case of SOAP UI.

REST-Representational State Transfer.

· Internally HTTP Protocol used by REST.

· In Rest We get the data by sending request using POST and also GET, PUT, DELETE, PATCH and multiple commands.

· this request and response are in XML, JASON, TEXT and also HTML.

· it supports multiple formats.

· Now a days all applications are used only REST Services not SOAP Services.