WebMethodAttribute Class

Methods within a class that have this attribute set are called XML Web service methods. The method and class must be public and running inside an ASP.NET Web application.

In the example below the method GetMachineName can be remotely called across the Web, because it has a WebMethodAttribute. GetUserName cannot be called remotely, because it does not have a WebMethodAttribute, even though it is public.

<%@ WebService Language="C#" Class="Util"%>
    using System;
    using System.Web.Services;
    public class Util: WebService {
       public string GetUserName() {
          return User.Identity.Name;
       }

       [ WebMethod(Description="Obtains the Server Machine Name",
       EnableSession=true)]
       public string GetMachineName() {
          return Server.MachineName;
       }
    }

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference