Web Service Description
A web service is a software system designed to support interoperable machine-to-machine interaction over a network. A web service can be thought of as a collection of interfaces that are published (made available) to other machines via HTTP(s). These interfaces follow specific rules that allow them to interact with each other.
Web Service Implementation
The implementation of a web service involves two parts: the interface definition and the actual implementation. The interface definition describes how messages should be formatted and sent across the network. This description is called the WSDL file. The implementation of this interface is done using a programming language that supports XML. The WSDL file contains information about the methods, inputs, outputs, and message types.
Web Service Client
A client uses a web service by sending requests to the server. The request includes the method name, input parameters, output parameters, and any other relevant data. The server processes the request and returns a response containing the results.