Visual FoxPro

Subscribe to Multiple Bitfinex Tickers on One Connection

See more WebSocket Examples

Subscribes to multiple ticker symbols on the public Bitfinex websocket ticker channel and receives ticker updates. Visual FoxPro

LOCAL lnSuccess
LOCAL loWs
LOCAL loRest
LOCAL lcResponseBody
LOCAL loJson1
LOCAL lnFinalFrame
LOCAL loJson2
LOCAL lnReceivedFinalFrame
LOCAL lnNumUpdatesReceived
LOCAL lcReceivedText

lnSuccess = 0

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

loWs = CreateObject('Chilkat.WebSocket')

* 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.

loRest = CreateObject('Chilkat.Rest')

* Connect to api.bitfinex.com
lnSuccess = loRest.Connect("api.bitfinex.com",443,1,0)
loWs.UseConnection(loRest)
loWs.AddClientHeaders()

lcResponseBody = loRest.FullRequestNoBody("GET","/ws")
lnSuccess = loWs.ValidateServerHandshake()
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    ? lcResponseBody
    ? loRest.ResponseHeader
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* After connecting, the bitfinex websocket server will send
* an info message that contains the actual version of the websocket stream.
* Receive that message..
lnSuccess = loWs.ReadFrame()
IF (lnSuccess <> 1) THEN
    ? "Failed to receive a frame"
    ? "ReadFrame fail reason = " + STR(loWs.ReadFrameFailReason)
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    CANCEL
ENDIF

* We should get this:
* {"event":"info","version":1.1,"platform":{"status":1}}
? loWs.GetFrameData()

* Subscribe to the BTCUSD ticker feed.
* See https://docs.bitfinex.com/docs for more information.
loJson1 = CreateObject('Chilkat.JsonObject')
loJson1.AppendString("event","subscribe")
loJson1.AppendString("channel","ticker")
loJson1.AppendString("pair","BTCUSD")

lnFinalFrame = 1
lnSuccess = loWs.SendFrame(loJson1.Emit(),lnFinalFrame)

* Subscribe to the ETHUSD ticker feed.
loJson2 = CreateObject('Chilkat.JsonObject')
loJson2.AppendString("event","subscribe")
loJson2.AppendString("channel","ticker")
loJson2.AppendString("pair","ETHUSD")

lnSuccess = loWs.SendFrame(loJson2.Emit(),lnFinalFrame)

* 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..
lnReceivedFinalFrame = 0
lnNumUpdatesReceived = 0
DO WHILE lnNumUpdatesReceived < 7

    lnSuccess = loWs.ReadFrame()
    IF (lnSuccess <> 1) THEN
        ? "Failed to receive a frame"
        ? "ReadFrame fail reason = " + STR(loWs.ReadFrameFailReason)
        ? loWs.LastErrorText
        RELEASE loWs
        RELEASE loRest
        RELEASE loJson1
        RELEASE loJson2
        CANCEL
    ENDIF

    * The responses we desire are in Text frames, where the opcode = 1.
    IF (loWs.FrameOpcodeInt = 1) THEN
        lcReceivedText = loWs.GetFrameData()
        ? lcReceivedText
        * 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"}
        lnNumUpdatesReceived = lnNumUpdatesReceived + 1
    ENDIF

ENDDO

* 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.
lnSuccess = loWs.SendClose(1,1000,"Closing this websocket.")
IF (lnSuccess <> 1) THEN
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    RELEASE loJson1
    RELEASE loJson2
    CANCEL
ENDIF

* Read the Close response.
lnSuccess = loWs.ReadFrame()
IF (lnSuccess <> 1) THEN
    ? "ReadFrame fail reason = " + STR(loWs.ReadFrameFailReason)
    ? loWs.LastErrorText
    RELEASE loWs
    RELEASE loRest
    RELEASE loJson1
    RELEASE loJson2
    CANCEL
ENDIF

? "Success."

RELEASE loWs
RELEASE loRest
RELEASE loJson1
RELEASE loJson2