Web Services in ASP.NET

Web Service represent the business logic encapsulated in a component. Since these services are hosted on a http server these are referred as web services.

Web Services are stateless in nature. i.e. Every request treated as a new client.

The request and response data is transmitted using XML. Hence, they are architecture neutral. i.e. A web service developed using JAVA(JSP) may be consumed by an ASP.NET web page.

The underlying protocol used is SOAP(Simple object access protocol) SOAP envelope consist of SOAP Header and SOAP Body.

Note:

A WebService class is derived from System.Web.Services.WebService

The attribute [WebService]  marked for the class indicates that the class will act as a web service.

The web service class may consist of several methods but only those methods which are marked by the attribute [WebMethod] will be exposed to the web service consumer.

A Consumer is the web application that will send request to the web service and obtain a response.

The attribute [WebService] has a property Namespace whose ideal value may be URL of the web service where it is hosted conventionally, otherwise it may be set to any non-existent URL.

Example:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Services;

[WebService(Namespace = "http://tempuri.org/")]

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.

// [System.Web.Script.Services.ScriptService]

public class Service : System.Web.Services.WebService

{

    public Service () {

        //Uncomment the following line if using designed components

        //InitializeComponent();

    }

    [WebMethod]

    public int Addition(int x,int y)

    {

        return x + y;

    }  

}

Consume a Web Service into ASP.NET Web Application

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page

{

    protected void Page_Load(object sender, EventArgs e)

    {

    }

    protected void Button1_Click(object sender, EventArgs e)

    {

        int a = Convert.ToInt32(TextBox1.Text);

        int b = Convert.ToInt32(TextBox2.Text);

        MyWebservice.Service affy = new MyWebservice.Service();

        int c = affy.Addition(a, b);

        TextBox3.Text = c.ToString();

    }

}

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