Web services is a way of communications or technology which allows us to develop interoperable distributed applications.
Interoperable – means Platform Independent & Language Independent.
Web services are required to communicate a different language application with a different language application. So, web services enables the communication between two different language based applications.
Distributed applications are server side applications. It exposes the objects on the networks.
Web Applications – A web application is a server side application and communicate with the end user directly. For web applications, end user is a client. In web application, end user sends the request directly to the web application, and the web application directly response to the end user only.
End users always use browser software to send the request to a web application.
Web Services – Web services is a server side application which always takes request from some other applications and response back to some other application. Web services program does not interact directly with the end user.
In Web services, other application acts as a client, directly end user does not act a client.
Web services always a distributed applications.
Web services are the client server model.
Client (e.g. mobile app) sends a request to the server with the response data, e.g. name of the city to find the current weather of this city. Data could be in any format – XML or JSON etc.
Server processes the request as per the requested data (name of the city) and returns the weather details from the database.
Then sends the data back to the client (mobile application) and client shows the response.
SOAP – Simple Object Access Protocol
REST – Representational State Transfer