B4X

Send and Receive WebSocket Frame

See more WebSocket Examples

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.

B4X

Dim success As Boolean = False

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

Dim ws As ChilkatWebSocket
ws.Initialize("ws")

'  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 ChilkatRest
rest.Initialize("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.
success = rest.Connect("websockets.chilkat.io", 80, False, False)
ws.UseConnection(rest)
ws.AddClientHeaders
Dim responseBodyIgnored As String = rest.FullRequestNoBody("GET", "/wsChilkatEcho.ashx")
success = ws.ValidateServerHandshake
If success <> True Then
    Log(ws.LastErrorText)
    Return
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 = ws.SendFrame("Hello World!", finalFrame)
If success <> True Then
    Log(ws.LastErrorText)
    Return
End If


'  Read an incoming frame.
success = ws.ReadFrame
If success <> True Then
    Log("Failed to receive a frame")
    Log("ReadFrame fail reason = " & ws.ReadFrameFailReason)
    Log(ws.LastErrorText)
    Return
End If


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

'  Close the websocket connection.
success = ws.SendClose(True, 1000, "Closing this websocket.")
If success <> True Then
    Log(ws.LastErrorText)
    Return
End If


'  Read the Close response.
success = ws.ReadFrame
If success <> True Then
    Log("ReadFrame fail reason = " & ws.ReadFrameFailReason)
    Log(ws.LastErrorText)
    Return
End If


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

Log("Success.")