What is a Web Service.?

Web services are small units of code designed to handle a limited set of tasks.

An example of a web service can be a small program designed to supply other applications with the latest stock exchange prices. Another example can be a small program designed to handle credit card payment.

Web services use the standard web protocols HTTP, XML, SOAP, WSDL, and UDDI.

• Web Services Standards (XML-based)
– SOAP (Simple Object Access Protocol)
– WSDL (Web Service Description Language)
– UDDI (Universal Description, Discovery, Integration)
– WS-I (integration), WS-Policy, WS-Security, etc.
• Chances and Challenges
– Application Wrappers to WS
– Web Services Compositions
– Holy Grail: large reusable library of WS with interoperability:
1,000 public WS ~ 1 Million private WS
– ROI (Return of Investments): > 10x ?
– Issues: Privacy, Security, Performance

example:-

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Web;
using System.Web.Services;

namespace WebServiceExample
{
    public class Service1 : System.Web.Services.WebService
    {
        public Service1()
        {
            
            InitializeComponent();
        }
        [WebMethod(Description="This Method prints HelloWorld")]
        public string HelloWorld()
        {
            return "Hello World";
        }
    }

}