(Xojo Plugin) Read Bitfinex WebSocket Ticker Channel

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

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim ws As New 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.

Dim rest As New Chilkat.Rest

//  Connect to api.bitfinex.com
Dim success As Boolean
success = rest.Connect("api.bitfinex.com",443,True,False)
success = ws.UseConnection(rest)
success = ws.AddClientHeaders()

Dim responseBody As String
responseBody = rest.FullRequestNoBody("GET","/ws")
success = ws.ValidateServerHandshake()
If (success <> True) Then
    System.DebugLog(ws.LastErrorText)
    System.DebugLog(responseBody)
    System.DebugLog(rest.ResponseHeader)
    Return
End If

//  After connecting, the bitfinex websocket server will send
//  an info message that contains the actual version of the websocket stream.
//  Receive that message..
success = ws.ReadFrame()
If (success <> True) Then
    System.DebugLog("Failed to receive a frame")
    System.DebugLog("ReadFrame fail reason = " + Str(ws.ReadFrameFailReason))
    System.DebugLog(ws.LastErrorText)
    Return
End If

//  We should get this:
//  {"event":"info","version":1.1,"platform":{"status":1}}
System.DebugLog(ws.GetFrameData())

//  Subscribe to the public ticker feed.
//  See https://docs.bitfinex.com/docs for more information.
Dim json As New Chilkat.JsonObject
success = json.AppendString("event","subscribe")
success = json.AppendString("channel","ticker")
success = json.AppendString("pair","BTCUSD")

Dim finalFrame As Boolean
finalFrame = True
success = ws.SendFrame(json.Emit(),finalFrame)

//  Read the response.
success = ws.ReadFrame()
If (success <> True) Then
    System.DebugLog("Failed to receive a frame")
    System.DebugLog("ReadFrame fail reason = " + Str(ws.ReadFrameFailReason))
    System.DebugLog(ws.LastErrorText)
    Return
End If

//  Examine the response
//  We should get this:
//  {"event":"subscribed","channel":"ticker","chanId":2751,"pair":"BTCUSD"}
System.DebugLog(ws.GetFrameData())

//  Begin reading the ticker feed.
//  We'll just read the 1st 5 updates and then exit..
Dim receivedFinalFrame As Boolean
receivedFinalFrame = False
Dim numUpdatesReceived As Int32
numUpdatesReceived = 0
While numUpdatesReceived < 5

    success = ws.ReadFrame()
    If (success <> True) Then
        System.DebugLog("Failed to receive a frame")
        System.DebugLog("ReadFrame fail reason = " + Str(ws.ReadFrameFailReason))
        System.DebugLog(ws.LastErrorText)
        Return
    End If

    //  The responses we desire are in Text frames, where the opcode = 1.
    If (ws.FrameOpcodeInt = 1) Then
        Dim receivedText As String
        receivedText = ws.GetFrameData()
        System.DebugLog(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
    End If

Wend

//  Close the websocket connection.
success = ws.SendClose(True,1000,"Closing this websocket.")
If (success <> True) Then
    System.DebugLog(ws.LastErrorText)
    Return
End If

//  Read the Close response.
success = ws.ReadFrame()
If (success <> True) Then
    System.DebugLog("ReadFrame fail reason = " + Str(ws.ReadFrameFailReason))
    System.DebugLog(ws.LastErrorText)
    Return
End If

System.DebugLog("Success.")