DataFlex

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.

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoWs
    Variant vRest
    Handle hoRest
    String sResponseBodyIgnored
    Variant vJpgData
    Handle hoJpgData
    Boolean iFinalFrame
    Boolean iReceivedFinalFrame
    Variant vJpgReceivedData
    Handle hoJpgReceivedData
    String sTemp1
    Integer iTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatWebSocket)) To hoWs
    If (Not(IsComObjectCreated(hoWs))) Begin
        Send CreateComObject of hoWs
    End

    // 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.

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End
    // 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.
    Get ComConnect Of hoRest "websockets.chilkat.io" 80 False False To iSuccess
    Get pvComObject of hoRest to vRest
    Get ComUseConnection Of hoWs vRest To iSuccess
    Get ComAddClientHeaders Of hoWs To iSuccess
    Get ComFullRequestNoBody Of hoRest "GET" "/wsChilkatEcho.ashx" To sResponseBodyIgnored
    Get ComValidateServerHandshake Of hoWs To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // This example sends a small JPG file (about 7KB) in a websocket frame.
    Get Create (RefClass(cComChilkatBinData)) To hoJpgData
    If (Not(IsComObjectCreated(hoJpgData))) Begin
        Send CreateComObject of hoJpgData
    End
    Get ComLoadFile Of hoJpgData "qa_data/jpg/starfish.jpg" To iSuccess

    Get ComNumBytes Of hoJpgData To iTemp1
    Showln "Number of bytes to send = " iTemp1

    // Send a frame containing the JPG image data.
    // This will be the first and final frame, and therefore this constitutes the entire message.
    Move True To iFinalFrame
    Get pvComObject of hoJpgData to vJpgData
    Get ComSendFrameBd Of hoWs vJpgData iFinalFrame To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // 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.
    Move False To iReceivedFinalFrame
    While (iReceivedFinalFrame = False)

        // 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.
        Get ComReadFrame Of hoWs To iSuccess
        If (iSuccess <> True) Begin
            Showln "Failed to receive a frame"
            Get ComReadFrameFailReason Of hoWs To iTemp1
            Showln "ReadFrame fail reason = " iTemp1
            Get ComLastErrorText Of hoWs To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        Get ComFinalFrame Of hoWs To iReceivedFinalFrame

        // Show the opcode and final frame bit for the frame just received:
        Get ComFrameOpcode Of hoWs To sTemp1
        Showln "Frame opcode: " sTemp1
        Showln "Final frame: " iReceivedFinalFrame
    Loop

    // Get the accumulated received data.
    Get Create (RefClass(cComChilkatBinData)) To hoJpgReceivedData
    If (Not(IsComObjectCreated(hoJpgReceivedData))) Begin
        Send CreateComObject of hoJpgReceivedData
    End
    Get pvComObject of hoJpgReceivedData to vJpgReceivedData
    Get ComGetFrameDataBd Of hoWs vJpgReceivedData To iSuccess
    Get ComNumBytes Of hoJpgReceivedData To iTemp1
    Showln "Received " iTemp1 " bytes"

    // Save the received JPG to a file so we can check it..
    Get ComWriteFile Of hoJpgReceivedData "qa_output/starfish_ws.jpg" To iSuccess

    // Close the websocket connection.
    Get ComSendClose Of hoWs True 1000 "Closing this websocket." To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Read the Close response.
    Get ComReadFrame Of hoWs To iSuccess
    If (iSuccess <> True) Begin
        Get ComReadFrameFailReason Of hoWs To iTemp1
        Showln "ReadFrame fail reason = " iTemp1
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Should receive the "Close" opcode.
    Get ComFrameOpcode Of hoWs To sTemp1
    Showln "Received opcode: " sTemp1
    // Should be the same status code we sent (1000)
    Get ComCloseStatusCode Of hoWs To iTemp1
    Showln "Received close status code: " iTemp1
    // The server may echo the close reason.  If not, this will be empty.
    Get ComCloseReason Of hoWs To sTemp1
    Showln "Echoed close reason: " sTemp1

    Showln "Success."


End_Procedure