(PureBasic) Subscribe to Multiple Bitfinex Tickers on One Connection

Subscribes to multiple ticker symbols on 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 BTCUSD ticker feed.
    ;  See https://docs.bitfinex.com/docs for more information.
    json1.i = CkJsonObject::ckCreate()
    If json1.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckAppendString(json1,"event","subscribe")
    CkJsonObject::ckAppendString(json1,"channel","ticker")
    CkJsonObject::ckAppendString(json1,"pair","BTCUSD")

    finalFrame.i = 1
    success = CkWebSocket::ckSendFrame(ws,CkJsonObject::ckEmit(json1),finalFrame)

    ;  Subscribe to the ETHUSD ticker feed.
    json2.i = CkJsonObject::ckCreate()
    If json2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::ckAppendString(json2,"event","subscribe")
    CkJsonObject::ckAppendString(json2,"channel","ticker")
    CkJsonObject::ckAppendString(json2,"pair","ETHUSD")

    success = CkWebSocket::ckSendFrame(ws,CkJsonObject::ckEmit(json2),finalFrame)

    ;  Begin reading the ticker feed.
    ; / This will include a single confirmation response for each subscription.

    ;  We'll just read the 1st 5 updates and then exit..
    receivedFinalFrame.i = 0
    numUpdatesReceived.i = 0
    While numUpdatesReceived < 7

        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(json1)
            CkJsonObject::ckDispose(json2)
            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]
            ;  Initially, a single confirmation response for each subscription would be received, such as this:
            ;  {"event":"subscribed","channel":"ticker","chanId":810,"pair":"BTCUSD"}
            numUpdatesReceived = numUpdatesReceived + 1
        EndIf

    Wend

    ;  This is sample output:
    ;  You can see that the 1st message received is the subscription confirmation for the BTCUSD subscribe request.
    ;  The next message is a BTCUSD ticker update.
    ;  The next message is the confirmation for the ETHUSD subscription.
    ;  The next message is an ETHUSD update.
    ;  The BTCUSD channel ID is "537", and the ETHUSD channel ID is "700".  The channel IDs are provided in the
    ;  subscription confirmation messages.  Each ticker update begins with the channel ID..

    ;  {"event":"subscribed","channel":"ticker","chanId":537,"pair":"BTCUSD"}
    ;  [537,6457.9,79.59102302,6458,22.49395741,-24.1,-0.0037,6457.9,13644.52820029,6540,6370.76958739]
    ;  {"event":"subscribed","channel":"ticker","chanId":700,"pair":"ETHUSD"}
    ;  [700,496.9,247.24493326,496.92,284.09636979,-2.47,-0.0049,496.9,74154.05945261,502.85,486.96]
    ;  [537,"hb"]
    ;  [700,"hb"]
    ;  [700,496.92,233.34338276,496.93,431.78867277,-2.45,-0.0049,496.92,74167.99173586,502.85,486.96]

    ;  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(json1)
        CkJsonObject::ckDispose(json2)
        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(json1)
        CkJsonObject::ckDispose(json2)
        ProcedureReturn
    EndIf

    Debug "Success."


    CkWebSocket::ckDispose(ws)
    CkRest::ckDispose(rest)
    CkJsonObject::ckDispose(json1)
    CkJsonObject::ckDispose(json2)


    ProcedureReturn
EndProcedure