Visual Basic 6.0

Send and Receive WebSocket Messages

See more WebSocket Examples

This example how to send and receive websocket messages.

A WebSocket message can be composed of one or more frames. The simple case is where a single frame is both the first and last frame in a message. This is the case where the 1st frame in the message has the "final frame" bit set.

This example demonstrates sending and receiving multi-frame messages.

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.

Visual Basic 6.0

Dim success As Long
success = 0

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

Dim ws As New ChilkatWebSocket

' 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 ChilkatRest
' 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.
success = rest.Connect("websockets.chilkat.io",80,0,0)
success = ws.UseConnection(rest)
success = ws.AddClientHeaders()
Dim responseBodyIgnored As String
responseBodyIgnored = rest.FullRequestNoBody("GET","/wsChilkatEcho.ashx")
success = ws.ValidateServerHandshake()
If (success <> 1) Then
    Debug.Print ws.LastErrorText
    Exit Sub
End If

' This example demonstrates sending and receiving a multi-frame message.

' The websocket message will be composed of three text lines, each frame will contain a single line.

' Send the 1st frame in the message.
Dim finalFrame As Long
finalFrame = 0
success = ws.SendFrame("This is the 1st frame" & vbCrLf,finalFrame)
If (success <> 1) Then
    Debug.Print ws.LastErrorText
    Exit Sub
End If

' Send the 2nd frame in the message.
success = ws.SendFrame("This is the 2nd frame" & vbCrLf,finalFrame)
If (success <> 1) Then
    Debug.Print ws.LastErrorText
    Exit Sub
End If

' Send the 3rd and final frame in the message.
finalFrame = 1
success = ws.SendFrame("This is the 3rd frame" & vbCrLf,finalFrame)
If (success <> 1) Then
    Debug.Print ws.LastErrorText
    Exit Sub
End If

' Read an incoming frames until we receive the final frame.
' Note: It may be that the echo server (websockets.chilkat.io) responds with 
' the full message in a single final frame.
Dim receivedFinalFrame As Long
receivedFinalFrame = 0
Do While receivedFinalFrame = 0

    success = ws.ReadFrame()
    If (success <> 1) Then
        Debug.Print "Failed to receive a frame"
        Debug.Print "ReadFrame fail reason = " & ws.ReadFrameFailReason
        Debug.Print ws.LastErrorText
        Exit Sub
    End If

    receivedFinalFrame = ws.FinalFrame

    ' Show the opcode and final frame bit for the frame just received:
    Debug.Print "Frame opcode: " & ws.FrameOpcode
    Debug.Print "Final frame: " & receivedFinalFrame
Loop

' Return the message accumulated in the above calls to ReadFrame.
Dim receivedMsg As String
receivedMsg = ws.GetFrameData()
Debug.Print "Received: " & receivedMsg

' Close the websocket connection.
success = ws.SendClose(1,1000,"Closing this websocket.")
If (success <> 1) Then
    Debug.Print ws.LastErrorText
    Exit Sub
End If

' Read the Close response.
success = ws.ReadFrame()
If (success <> 1) Then
    Debug.Print "ReadFrame fail reason = " & ws.ReadFrameFailReason
    Debug.Print ws.LastErrorText
    Exit Sub
End If

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

Debug.Print "Success."