Visual FoxPro

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.

Visual FoxPro

LOCAL lnSuccess
LOCAL loWs
LOCAL loRest
LOCAL lcResponseBodyIgnored
LOCAL lnFinalFrame
LOCAL lcReceivedStr

lnSuccess = 0

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

loWs = CreateObject('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.

loRest = CreateObject('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.
lnSuccess = loRest.Connect("websockets.chilkat.io",80,0,0)
loWs.UseConnection(loRest)
loWs.AddClientHeaders()
lcResponseBodyIgnored = loRest.FullRequestNoBody("GET","/wsChilkatEcho.ashx")
lnSuccess = loWs.ValidateServerHandshake()
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* 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.
lnFinalFrame = 1
lnSuccess = loWs.SendFrame("Hello World!",lnFinalFrame)
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* Read an incoming frame.
lnSuccess = loWs.ReadFrame()
IF (lnSuccess <> 1) THEN
    ? "Failed to receive a frame"
    ? "ReadFrame fail reason = " + STR(loWs.ReadFrameFailReason)
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* Show the string that was received.
lcReceivedStr = loWs.GetFrameData()
? "Received: " + lcReceivedStr

* Close the websocket connection.
lnSuccess = loWs.SendClose(1,1000,"Closing this websocket.")
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* Read the Close response.
lnSuccess = loWs.ReadFrame()
IF (lnSuccess <> 1) THEN
    ? "ReadFrame fail reason = " + STR(loWs.ReadFrameFailReason)
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* Should receive the "Close" opcode.
? "Received opcode: " + loWs.FrameOpcode
* Should be the same status code we sent (1000)
? "Received close status code: " + STR(loWs.CloseStatusCode)
* The server may echo the close reason.  If not, this will be empty.
? "Echoed close reason: " + loWs.CloseReason

? "Success."

RELEASE loWs
RELEASE loRest