PureBasic

WebSocket Send/Receive Binary Data

See more WebSocket Examples

Demonstrates how to send and receive binary data on a websocket. 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.

PureBasic

IncludeFile "CkBinData.pb"
IncludeFile "CkRest.pb"
IncludeFile "CkWebSocket.pb"

Procedure ChilkatExample()

    success.i = 0

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

    ws.i = CkWebSocket::ckCreate()
    If ws.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; 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.

    rest.i = CkRest::ckCreate()
    If rest.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; 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 = CkRest::ckConnect(rest,"websockets.chilkat.io",80,0,0)
    CkWebSocket::ckUseConnection(ws,rest)
    CkWebSocket::ckAddClientHeaders(ws)
    responseBodyIgnored.s = CkRest::ckFullRequestNoBody(rest,"GET","/wsChilkatEcho.ashx")
    success = CkWebSocket::ckValidateServerHandshake(ws)
    If success <> 1
        Debug CkWebSocket::ckLastErrorText(ws)
        CkWebSocket::ckDispose(ws)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; This example sends a small JPG file (about 7KB) in a websocket frame.
    jpgData.i = CkBinData::ckCreate()
    If jpgData.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkBinData::ckLoadFile(jpgData,"qa_data/jpg/starfish.jpg")

    Debug "Number of bytes to send = " + Str(CkBinData::ckNumBytes(jpgData))

    ; Send a frame containing the JPG image data.
    ; This will be the first and final frame, and therefore this constitutes the entire message.
    finalFrame.i = 1
    success = CkWebSocket::ckSendFrameBd(ws,jpgData,finalFrame)
    If success <> 1
        Debug CkWebSocket::ckLastErrorText(ws)
        CkWebSocket::ckDispose(ws)
        CkRest::ckDispose(rest)
        CkBinData::ckDispose(jpgData)
        ProcedureReturn
    EndIf

    ; Read the echoed binary frame(s).
    ; (We sent the JPG file in a single frame, but we may receive the echo in multiple frames, but it will be one message.)
    ; Read an incoming frames until we receive the final frame.
    receivedFinalFrame.i = 0
    While receivedFinalFrame = 0

        ; The ws object is accumulating the received data internally.  Once we get the final frame, we'll get the 
        ; accumulated data which should constitute the entire JPG.
        success = CkWebSocket::ckReadFrame(ws)
        If success <> 1
            Debug "Failed to receive a frame"
            Debug "ReadFrame fail reason = " + Str(CkWebSocket::ckReadFrameFailReason(ws))
            Debug CkWebSocket::ckLastErrorText(ws)
            CkWebSocket::ckDispose(ws)
            CkRest::ckDispose(rest)
            CkBinData::ckDispose(jpgData)
            ProcedureReturn
        EndIf

        receivedFinalFrame = CkWebSocket::ckFinalFrame(ws)

        ; Show the opcode and final frame bit for the frame just received:
        Debug "Frame opcode: " + CkWebSocket::ckFrameOpcode(ws)
        Debug "Final frame: " + Str(receivedFinalFrame)
    Wend

    ; Get the accumulated received data.
    jpgReceivedData.i = CkBinData::ckCreate()
    If jpgReceivedData.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkWebSocket::ckGetFrameDataBd(ws,jpgReceivedData)
    Debug "Received " + Str(CkBinData::ckNumBytes(jpgReceivedData)) + " bytes"

    ; Save the received JPG to a file so we can check it..
    CkBinData::ckWriteFile(jpgReceivedData,"qa_output/starfish_ws.jpg")

    ; Close the websocket connection.
    success = CkWebSocket::ckSendClose(ws,1,1000,"Closing this websocket.")
    If success <> 1
        Debug CkWebSocket::ckLastErrorText(ws)
        CkWebSocket::ckDispose(ws)
        CkRest::ckDispose(rest)
        CkBinData::ckDispose(jpgData)
        CkBinData::ckDispose(jpgReceivedData)
        ProcedureReturn
    EndIf

    ; Read the Close response.
    success = CkWebSocket::ckReadFrame(ws)
    If success <> 1
        Debug "ReadFrame fail reason = " + Str(CkWebSocket::ckReadFrameFailReason(ws))
        Debug CkWebSocket::ckLastErrorText(ws)
        CkWebSocket::ckDispose(ws)
        CkRest::ckDispose(rest)
        CkBinData::ckDispose(jpgData)
        CkBinData::ckDispose(jpgReceivedData)
        ProcedureReturn
    EndIf

    ; Should receive the "Close" opcode.
    Debug "Received opcode: " + CkWebSocket::ckFrameOpcode(ws)
    ; Should be the same status code we sent (1000)
    Debug "Received close status code: " + Str(CkWebSocket::ckCloseStatusCode(ws))
    ; The server may echo the close reason.  If not, this will be empty.
    Debug "Echoed close reason: " + CkWebSocket::ckCloseReason(ws)

    Debug "Success."


    CkWebSocket::ckDispose(ws)
    CkRest::ckDispose(rest)
    CkBinData::ckDispose(jpgData)
    CkBinData::ckDispose(jpgReceivedData)


    ProcedureReturn
EndProcedure