Web Service with Asp.Net

What is Web Service?

Web Service is an application that is designed to interact directly with other applications over the internet. In simple sense, Web Services are means for interacting with objects over the Internet. The Web serivce consumers are able to invoke method calls on remote objects by using SOAP and HTTP over the Web. Web Service is language independent and Web Services communicate by using standard web protocols and data formats, such as

1. HTTP
2. XML
3. SOAP

ASP.NET Web Services:

Web Services are simple and easy to understand. It is possible, in fact, to author a simple application that surfaces data as XML conforming to the SOAP specification. It would also be relatively straightforward to build an application capable of receiving SOAP messages over HTTP and deriving meaningful value out of it. For those of you familiar with PERL, this could simply be a matter of using RegEx to parse the value out of the XML result; it's just another string.

However, just as we use frameworks such as ASP and ASP.NET to build Web applications, we would much rather use a framework for building Web Services. The reasoning is quite logical. We don't need to reinvent the plumbing—that is, at a high level, the capability to serialize our data as XML, transport the data using HTTP, and de-serialize the XML back to meaningful data. Instead, we want a framework that makes building Web Services easy, allowing us to focus on the application logic not the plumbing. ASP.NET provides this framework for us.

From a developer's point of view, if you have ever written application logic, you have the required skills to author ASP.NET Web Services. More importantly, if you're at all familiar with ASP or ASP.NET application services, (application state memory, and so on) you can also leverage these skills when you build ASP.NET Web Services.

Creating a Web Service:

Let us write a simple module that will provide basic arithmetic operations to other applications. The user of our application will have to provide us 2 numbers and we will perform the requested operation like Addition, Subtraction and Multiplication.

So, the first thing we need to do is to create our web service. We can do this by creating a website of type ASP.NETWeb service. This will give us a skeleton to write our web service code in.

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

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

public class Service : System.Web.Services.WebService

{

    public Service () {

        //Uncomment the following line if using designed components

        //InitializeComponent();

    }

    [WebMethod]

    public string HelloWorld() {

        return "Hello World";

    }

}

The attribute Web Service tells that this class contains the code for web service. The namespace is what is used to identify the web service. The Web Method attribute specifies the methods which our web service is providing.

Let us now go ahead and write code to have our functions in this webservice.

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

[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

public class Service : System.Web.Services.WebService

{

    public Service ()

    {

        //Uncomment the following line if using designed components

        //InitializeComponent();

    }

    [WebMethod]

    public int Add(int x, int y)

    {

        return x+y;

    }

    [WebMethod]

    public int Subtract(int x, int y)

    {

        return x - y;

    }

    [WebMethod]

    public int Multiply(int x, int y)

    {

        return x * y;

    }

}

 Also Read :

Multithreading in Asp.Net

Event Handling in Asp.Net

Statemanagement in Asp.Net