' This is the program entry point. It allows the user to enter 
' a server name that is used to locate its current homepage.
Public Shared Sub Main(ByVal args() As String)
    Dim proxy As String = Nothing
    Dim port As Integer = 80

    ' Define a regular expression to parse the user's input.
    ' This is a security check. It allows only
    ' alphanumeric input strings between 2 to 40 characters long.
    Dim rex As New Regex("^[a-zA-Z]\w{1,39}$")

    If args.Length = 0 Then
        ' Show how to use this program.
        showUsage()
        Return
    End If

    proxy = args(0)
    If (Not (rex.Match(proxy)).Success) Then
        Console.WriteLine("Input string format not allowed.")
        Return
    End If

    ' Create a proxy object.  
    Dim proxyAdd As String
    proxyAdd = "http://" + proxy + ":" + port.ToString()


    Dim DefaultProxy As New WebProxy(proxyAdd, True)

    ' Set the proxy that all HttpWebRequest instances use.
    WebRequest.DefaultWebProxy = DefaultProxy


    ' Get the base interface for proxy access for the 
    ' WebRequest-based classes.
    Dim Iproxy As IWebProxy = WebRequest.DefaultWebProxy

    ' Set the maximum number of ServicePoint instances to maintain.
    ' Note that, if a ServicePoint instance for that host already 
    ' exists when your application requests a connection to
    ' an Internet resource, the ServicePointManager object
    ' returns this existing ServicePoint. If none exists 
    ' for that host, it creates a new ServicePoint instance.
    ServicePointManager.MaxServicePoints = 4

    ' Set the maximum idle time of a ServicePoint instance to 10 seconds.
    ' After the idle time expires, the ServicePoint object is eligible for
    ' garbage collection and cannot be used by the ServicePointManager.
    ServicePointManager.MaxServicePointIdleTime = 10000


    ServicePointManager.UseNagleAlgorithm = True
    ServicePointManager.Expect100Continue = True
    ServicePointManager.CheckCertificateRevocationList = True
    ServicePointManager.DefaultConnectionLimit = _
        ServicePointManager.DefaultPersistentConnectionLimit
    ' Create the Uri object for the resource you want to access.
    Dim MS As New Uri("http://msdn.microsoft.com/")

    ' Use the FindServicePoint method to find an existing 
    ' ServicePoint object or to create a new one.   
    Dim servicePoint As ServicePoint = ServicePointManager.FindServicePoint(MS, Iproxy)
    ShowProperties(servicePoint)
    Dim hashCode As Integer = servicePoint.GetHashCode()
    Console.WriteLine(("Service point hashcode: " + hashCode.ToString()))

    ' Make a request with the same scheme identifier and host fragment
    ' used to create the previous ServicePoint object.
    makeWebRequest(hashCode, "http://msdn.microsoft.com/library/")

End Sub