(PureBasic) Read Bitfinex WebSocket Ticker Channel

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

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkRest.pb"
IncludeFile "CkJsonObject.pb"
IncludeFile "CkWebSocket.pb"

Procedure ChilkatExample()

    ;  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 api.bitfinex.com
    success.i = CkRest::ckConnect(rest,"api.bitfinex.com",443,1,0)
    CkWebSocket::ckUseConnection(ws,rest)
    CkWebSocket::ckAddClientHeaders(ws)

    responseBody.s = CkRest::ckFullRequestNoBody(rest,"GET","/ws")
    success = CkWebSocket::ckValidateServerHandshake(ws)
    If success <> 1
        Debug CkWebSocket::ckLastErrorText(ws)
        Debug responseBody
        Debug CkRest::ckResponseHeader(rest)
        CkWebSocket::ckDispose(ws)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

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

    ;  We should get this:
    ;  {"event":"info","version":1.1,"platform":{"status":1}}
    Debug CkWebSocket::ckGetFrameData(ws)

    ;  Subscribe to the public ticker feed.
    ;  See https://docs.bitfinex.com/docs for more information.
    json.i = CkJsonObject::ckCreate()
    If json.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckAppendString(json,"event","subscribe")
    CkJsonObject::ckAppendString(json,"channel","ticker")
    CkJsonObject::ckAppendString(json,"pair","BTCUSD")

    finalFrame.i = 1
    success = CkWebSocket::ckSendFrame(ws,CkJsonObject::ckEmit(json),finalFrame)

    ;  Read the response.
    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)
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    EndIf

    ;  Examine the response
    ;  We should get this:
    ;  {"event":"subscribed","channel":"ticker","chanId":2751,"pair":"BTCUSD"}
    Debug CkWebSocket::ckGetFrameData(ws)

    ;  Begin reading the ticker feed.
    ;  We'll just read the 1st 5 updates and then exit..
    receivedFinalFrame.i = 0
    numUpdatesReceived.i = 0
    While numUpdatesReceived < 5

        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)
            CkJsonObject::ckDispose(json)
            ProcedureReturn
        EndIf

        ;  The responses we desire are in Text frames, where the opcode = 1.
        If CkWebSocket::ckFrameOpcodeInt(ws) = 1
            receivedText.s = CkWebSocket::ckGetFrameData(ws)
            Debug receivedText
            ;  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]
            numUpdatesReceived = numUpdatesReceived + 1
        EndIf

    Wend

    ;  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)
        CkJsonObject::ckDispose(json)
        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)
        CkJsonObject::ckDispose(json)
        ProcedureReturn
    EndIf

    Debug "Success."


    CkWebSocket::ckDispose(ws)
    CkRest::ckDispose(rest)
    CkJsonObject::ckDispose(json)


    ProcedureReturn
EndProcedure