Eu estou tentando criar o servidor WebSocket mais simples com VB.NET. Consigo implementar o handshake, mas não consigo enviar mensagens após o handshake. O seguinte é meu código:

Dim serverTcp As TcpListener
Dim serverThread As Thread

Sub Main()
    '' Start server
    serverThread = New Thread(AddressOf serverProc)
    serverThread.Start()
End Sub

Private Sub serverProc()
    '' Listen to port 8181
    serverTcp = New TcpListener(8181)
    serverTcp.Start()

    Console.WriteLine("Listen to port 8181 ...")

    '' Accept any connection
    While (True)
        Dim curSocket As Socket = serverTcp.AcceptSocket()
        Dim thread As New Thread(AddressOf clientProc)
        thread.Start(curSocket)
    End While
End Sub

Private Sub clientProc(ByVal sck As Socket)
    Dim netStream As New NetworkStream(sck)
    Dim netReader As New IO.StreamReader(netStream)
    Dim netWriter As New IO.StreamWriter(netStream)

    Dim key As String = ""

    Console.WriteLine("Accept new connection ...")

    '' Reading handshake message
    While (True)
        Dim line As String = netReader.ReadLine()
        If line.Length = 0 Then
            Exit While
        End If

        If (line.StartsWith("Sec-WebSocket-Key: ")) Then
            key = line.Split(":")(1).Trim()
        End If

        Console.WriteLine("Data: " & line)
    End While

    '' Calculate accept-key
    key += "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
    key = getSHA1Hash(key)

    '' Response handshake message
    Dim response As String
    response = "HTTP/1.1 101 Switching Protocols" & vbCrLf
    response &= "Upgrade: websocket" & vbCrLf
    response &= "Connection: Upgrade" & vbCrLf
    response &= "Sec-WebSocket-Accept: " & key & vbCrLf & vbCrLf
    netWriter.Write(response)
    netWriter.Flush()

    '' Sending Hello World message
    Dim message As String = "Hello World"
    Dim messageByte() As Byte = System.Text.Encoding.UTF8.GetBytes(message)
    Dim startByte() As Byte = {&H0}
    Dim endByte() As Byte = {&HFF}

    sck.Send(startByte, 1, 0)
    sck.Send(messageByte)
    sck.Send(endByte, 1, 0)
End Sub

Function getSHA1Hash(ByVal strToHash As String) As String
    Dim sha1Obj As New Security.Cryptography.SHA1CryptoServiceProvider
    Dim bytesToHash() As Byte = System.Text.Encoding.ASCII.GetBytes(strToHash)
    Dim result As String

    bytesToHash = sha1Obj.ComputeHash(bytesToHash)
    result = Convert.ToBase64String(bytesToHash)

    Return result
End Function

O padrão diz que preciso enviar0x00 byte, seguido por byte de UTF8 e terminar com0xFF byte. Eu fiz como diz ainda meu cliente HTML não pode receber a mensagem.

O seguinte é o meu código HTML5:

<script>
if('WebSocket' in window){
  connect('ws://localhost:8181/service');
}

function connect(host) {
  var ws = new WebSocket(host);
  ws.onopen = function () {
    alert('connected');
  };

  ws.onmessage = function (evt) {  
    alert('reveived data:'+evt.data);
  };

  ws.onclose = function () {
    alert('socket closed');
  };
};
</script>