Visual FoxPro

Read Bitfinex WebSocket Ticker Channel

See more WebSocket Examples

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

LOCAL lnSuccess
LOCAL loWs
LOCAL loRest
LOCAL lcResponseBody
LOCAL loJson
LOCAL lnFinalFrame
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 public ticker feed.
* See https://docs.bitfinex.com/docs for more information.
loJson = CreateObject('Chilkat.JsonObject')
loJson.AppendString("event","subscribe")
loJson.AppendString("channel","ticker")
loJson.AppendString("pair","BTCUSD")

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

* Read the response.
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 loJson
    CANCEL
ENDIF

* Examine the response
* We should get this:
* {"event":"subscribed","channel":"ticker","chanId":2751,"pair":"BTCUSD"}
? loWs.GetFrameData()

* Begin reading the ticker feed.
* We'll just read the 1st 5 updates and then exit..
lnReceivedFinalFrame = 0
lnNumUpdatesReceived = 0
DO WHILE lnNumUpdatesReceived < 5

    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 loJson
        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]
        lnNumUpdatesReceived = lnNumUpdatesReceived + 1
    ENDIF

ENDDO

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

? "Success."

RELEASE loWs
RELEASE loRest
RELEASE loJson