(DataFlex) Read Bitfinex WebSocket Ticker Channel

Subscribes to the public Bitfinex websocket ticker channel and receives ticker updates.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

Use ChilkatAx-win32.pkg

Procedure Test
    Handle hoWs
    Variant vRest
    Handle hoRest
    Boolean iSuccess
    String sResponseBody
    Handle hoJson
    Boolean iFinalFrame
    Boolean iReceivedFinalFrame
    Integer iNumUpdatesReceived
    String sReceivedText
    String sTemp1
    Integer iTemp1

    // 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 api.bitfinex.com
    Get ComConnect Of hoRest "api.bitfinex.com" 443 True 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" "/ws" To sResponseBody
    Get ComValidateServerHandshake Of hoWs To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoWs To sTemp1
        Showln sTemp1
        Showln sResponseBody
        Get ComResponseHeader Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // After connecting, the bitfinex websocket server will send
    // an info message that contains the actual version of the websocket stream.
    // Receive that message..
    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

    // We should get this:
    // {"event":"info","version":1.1,"platform":{"status":1}}
    Get ComGetFrameData Of hoWs To sTemp1
    Showln sTemp1

    // Subscribe to the public ticker feed.
    // See https://docs.bitfinex.com/docs for more information.
    Get Create (RefClass(cComChilkatJsonObject)) To hoJson
    If (Not(IsComObjectCreated(hoJson))) Begin
        Send CreateComObject of hoJson
    End
    Get ComAppendString Of hoJson "event" "subscribe" To iSuccess
    Get ComAppendString Of hoJson "channel" "ticker" To iSuccess
    Get ComAppendString Of hoJson "pair" "BTCUSD" To iSuccess

    Move True To iFinalFrame
    Get ComEmit Of hoJson To sTemp1
    Get ComSendFrame Of hoWs sTemp1 iFinalFrame To iSuccess

    // Read the response.
    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

    // Examine the response
    // We should get this:
    // {"event":"subscribed","channel":"ticker","chanId":2751,"pair":"BTCUSD"}
    Get ComGetFrameData Of hoWs To sTemp1
    Showln sTemp1

    // Begin reading the ticker feed.
    // We'll just read the 1st 5 updates and then exit..
    Move False To iReceivedFinalFrame
    Move 0 To iNumUpdatesReceived
    While (iNumUpdatesReceived < 5)

        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

        // The responses we desire are in Text frames, where the opcode = 1.
        Get ComFrameOpcodeInt Of hoWs To iTemp1
        If (iTemp1 = 1) Begin
            Get ComGetFrameData Of hoWs To sReceivedText
            Showln sReceivedText
            // Should receive a line of text such as this:
            // [2751,7349,36.34269559,7349.1,41.01777063,-116.2,-0.0156,7349.1,22188.26055319,7560,7270.5]
            Move (iNumUpdatesReceived + 1) To iNumUpdatesReceived
        End

    Loop

    // 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

    Showln "Success."


End_Procedure