<%@ WebService Language="VB" class="MyUser" %>
Imports System
Imports System.Web.Services
Imports System.Web.Services.Protocols

Public Class MyUser
    Inherits WebService    

    <SoapDocumentMethod(Action := "http://www.contoso.com/Sample", _
    RequestNamespace := "http://www.contoso.com/Request", _
    RequestElementName := "GetUserNameRequest", _
    ResponseNamespace := "http://www.contoso.com/Response", _
    ResponseElementName := "GetUserNameResponse"), _
    WebMethod(Description := "Obtains the User Name")> _
    Public Function GetUserName() As UserName

        Dim temp As String
        Dim pos As Integer
        Dim NewUser As New UserName()

        ' Get the full user name, including the domain name if applicable.
        temp = User.Identity.Name

        ' Deterime whether the user is part of a Domain by searching for a backslash.
        pos = temp.IndexOf("\")

        ' Parse the domain name out of the string, if one exists.
        If pos <= 0 Then
            NewUser.Name = User.Identity.Name
        Else
            NewUser.Name = temp.Remove(0, pos + 1)
            NewUser.Domain = temp.Remove(pos, temp.Length - pos)
        End If
        Return NewUser
    End Function
End Class 

Public Class UserName

    Public Name As String
    Public Domain As String
End Class

<%@ WebService Language="C#" class="MyUser" %>
 using System;
 using System.Web.Services;
 using System.Web.Services.Protocols;

 public class MyUser : WebService {

       [ SoapDocumentMethod(Action="http://www.contoso.com/Sample", 
           RequestNamespace="http://www.contoso.com/Request",
           RequestElementName="GetUserNameRequest",
           ResponseNamespace="http://www.contoso.com/Response",
           ResponseElementName="GetUserNameResponse")]
      [ WebMethod(Description="Obtains the User Name") ]
      public UserName GetUserName() {
           string temp;
           int pos;
           UserName NewUser = new UserName();

           // Get the full user name, including the domain name if applicable.
           temp = User.Identity.Name;

           // Deterime whether the user is part of a domain by searching for a backslash.
           pos = temp.IndexOf("\\");

           // Parse the domain name out of the string, if one exists.
           if (pos <= 0)
                 NewUser.Name = User.Identity.Name;
           else {
               NewUser.Name = temp.Remove(0,pos+1);
                 NewUser.Domain = temp.Remove(pos,temp.Length-pos);
           } 
       return NewUser;
      }

 }   

 public class UserName {

     public string Name;
     public string Domain;
 }