<ToolboxItem(False)> _
Public Class Service1
     Inherits System.Web.Services.WebService
 
<WebMethod(EnableSession:=True)> _
     Public Function GetMessage() As String
         Return Session("Message")
     End Function
 
<WebMethod(EnableSession:=True)> _
     Public Sub SetMessage(ByVal pMessage As String)
         Session("Message") = pMessage
     End Sub
 
End Class

Public Class Form1
 
Private myService As New Service1.Service1SoapClient
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
         myService.SetMessage("Das ist ein Test")
 
MsgBox(myService.GetMessage)
     End Sub
End Class