(VB.NET UWP/WinRT) Send and Receive WebSocket Frame

Demonstrates how to send a websocket text frame to a websocket echo server. This example uses Chilkat's websocket test echo server at ws://websockets.chilkat.io/wsChilkatEcho.ashx

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim ws As New Chilkat.WebSocket

' For brevity, this example does not check for errors when etablishing the WebSocket connection.
' See Establish WebSocket Connection for more complete sample code for making the connection.

Dim rest As New Chilkat.Rest
' Connect to websockets.chilkat.io
' IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
' IMPORTANT: The websockets.chilkat.io server imposes the following limitations: 
' ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
Dim success As Boolean = Await rest.ConnectAsync("websockets.chilkat.io",80,False,False)
ws.UseConnection(rest)
ws.AddClientHeaders()
Dim responseBodyIgnored As String = Await rest.FullRequestNoBodyAsync("GET","/wsChilkatEcho.ashx")
success = ws.ValidateServerHandshake()
If (success <> True) Then
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


' This example demonstrates sending a frame and receiving a text frame.


' Send a frame containing the string "Hello World!"
' This will be the first and final frame, and therefore this constitutes the entire message.
Dim finalFrame As Boolean = True
success = Await ws.SendFrameAsync("Hello World!",finalFrame)
If (success <> True) Then
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


' Read an incoming frame.
success = Await ws.ReadFrameAsync()
If (success <> True) Then
    Debug.WriteLine("Failed to receive a frame")
    Debug.WriteLine("ReadFrame fail reason = " & ws.ReadFrameFailReason)
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


' Show the string that was received.
Dim receivedStr As String = ws.GetFrameData()
Debug.WriteLine("Received: " & receivedStr)

' Close the websocket connection.
success = Await ws.SendCloseAsync(True,1000,"Closing this websocket.")
If (success <> True) Then
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


' Read the Close response.
success = Await ws.ReadFrameAsync()
If (success <> True) Then
    Debug.WriteLine("ReadFrame fail reason = " & ws.ReadFrameFailReason)
    Debug.WriteLine(ws.LastErrorText)
    Exit Sub
End If


' Should receive the "Close" opcode.
Debug.WriteLine("Received opcode: " & ws.FrameOpcode)
' Should be the same status code we sent (1000)
Debug.WriteLine("Received close status code: " & ws.CloseStatusCode)
' The server may echo the close reason.  If not, this will be empty.
Debug.WriteLine("Echoed close reason: " & ws.CloseReason)

Debug.WriteLine("Success.")