[SecurityPermissionAttribute(SecurityAction.Demand, Unrestricted = true)]

internal static object GetWebService(string webServiceAsmxUrl, string serviceName)

{

    WebClient client = new WebClient();

    // Connect To the web service

    Stream stream = client.OpenRead(webServiceAsmxUrl + "?wsdl");

    // Now read the WSDL file describing a service.

    ServiceDescription description = ServiceDescription.Read(stream);

    ///// LOAD THE DOM /////////

    // Initialize a service description importer.

    ServiceDescriptionImporter importer = new ServiceDescriptionImporter();

    importer.ProtocolName = "Soap12"; // Use SOAP 1.2.

    importer.AddServiceDescription(description, null, null);

    // Generate a proxy client.

    importer.Style = ServiceDescriptionImportStyle.Client;

    // Generate properties to represent primitive values.

    importer.CodeGenerationOptions = System.Xml.Serialization.CodeGenerationOptions.GenerateProperties;

    // Initialize a Code-DOM tree into which we will import the service.

    CodeNamespace nmspace = new CodeNamespace();

    CodeCompileUnit unit1 = new CodeCompileUnit();

    unit1.Namespaces.Add(nmspace);

    // Import the service into the Code-DOM tree. This creates proxy code that uses the service.

    ServiceDescriptionImportWarnings warning = importer.Import(nmspace, unit1);

    if (warning == 0) // If zero then we are good to go

    {

        // Generate the proxy code

        CodeDomProvider provider1 = CodeDomProvider.CreateProvider("CSharp");

        // Compile the assembly proxy with the appropriate references

        string[] assemblyReferences = new string[5]

                                                {

                                                    "System.dll",

                                                    "System.Web.Services.dll",

                                                    "System.Web.dll",

                                                    "System.Xml.dll",

                                                    "System.Data.dll"

                                                };

        CompilerParameters parms = new CompilerParameters(assemblyReferences);

        CompilerResults results = provider1.CompileAssemblyFromDom(parms, unit1);

        // Check For Errors

        if (results.Errors.Count > 0)

        {

            throw new System.Exception("Compile Error Occured calling webservice. Check Debug ouput window.");

        }

        // Finally, Invoke the web service method

        object wsvcClass = results.CompiledAssembly.CreateInstance(serviceName);

        return wsvcClass;

    }

    else

    {

        return null;

    }

}

internal static string[] Methods(object webService)

{

    var list = webService.GetType().GetMethods().

            Where(x => x.GetCustomAttributes(typeof(SoapDocumentMethodAttribute), false).Length > 0).

            Select(y => y.Name).ToArray();

    return list;

}

internal static List<KeyValuePair<string, Type>> GetParameters(object service, string methodeName)

{

    var list = new List<KeyValuePair<string, Type>>();

    MethodInfo mi = service.GetType().GetMethod(methodeName);

    foreach (var parameter in mi.GetParameters())

    {

        list.Add(new KeyValuePair<string, Type>(parameter.Name, parameter.ParameterType));

    }

    return list;

}

internal static object Invoke(object service, string methodName, object[] parameters)

{

    return service.GetType().GetMethod(methodName).Invoke(service, parameters);

}

public class MyWebService : System.Web.Services.WebService

{

    [WebMethod]

    public string HelloWorld()

    {

        return "Hello World";

    }

    [WebMethod]

    public int Add(int a, int b)

    {

        return a + b;

    }

}

<table id="tblParam" runat="server">

</table>

protected void ddlService_SelectedIndexChanged(object sender, EventArgs e)

{

    ddlMethod.Items.Clear();

    ddlMethod.Items.Add("Select Method");

    if (Session[ddlService.SelectedValue] == null)

    {

        Session[ddlService.SelectedValue] =

                WsProxy.GetWebService(ddlService.SelectedItem.Text, ddlService.SelectedItem.Value);

    }

    ddlMethod.Items.AddRange(WsProxy.Methods(Session[ddlService.SelectedValue]).

                            Select(x => new ListItem(x)).ToArray());

}

protected void ddlMethod_SelectedIndexChanged(object sender, EventArgs e)

{

    var parameters = WsProxy.GetParameters(Session[ddlService.SelectedValue], ddlMethod.Text);

    foreach (var item in parameters)

    {

        HtmlTableRow row = new HtmlTableRow();

        HtmlTableCell cell = new HtmlTableCell();

        cell.InnerHtml = string.Format("{0} ({1}): <input type='text' name='{2}'/>",

                                        item.Key, item.Value.Name, item.Key);

        row.Cells.Add(cell);

        tblParam.Rows.Add(row);

    }

}

protected void btnInvoke_Click(object sender, EventArgs e)

{

    object service = Session[ddlService.SelectedValue];

    var parameters = WsProxy.GetParameters(service, ddlMethod.Text);

    object[] @params = new object[parameters.Count];

    for (int i = 0; i < parameters.Count; i++)

    {

        var data = Request[parameters[i].Key];

        @params[i] = Convert.ChangeType(data, parameters[i].Value);

    }

    var res = WsProxy.Invoke(service, ddlMethod.Text, @params);

}