B4X

Subscribe to Multiple Bitfinex Tickers on One Connection

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Subscribes to multiple ticker symbols on the public Bitfinex websocket ticker channel and receives ticker updates. B4X

Dim success As Boolean = False

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

Dim ws As ChilkatWebSocket
ws.Initialize("ws")

'  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 ChilkatRest
rest.Initialize("rest")

'  Connect to api.bitfinex.com
success = rest.Connect("api.bitfinex.com", 443, True, False)
ws.UseConnection(rest)
ws.AddClientHeaders

Dim responseBody As String = rest.FullRequestNoBody("GET", "/ws")
success = ws.ValidateServerHandshake
If success <> True Then
    Log(ws.LastErrorText)
    Log(responseBody)
    Log(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
    Log("Failed to receive a frame")
    Log("ReadFrame fail reason = " & ws.ReadFrameFailReason)
    Log(ws.LastErrorText)
    Return
End If


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

'  Subscribe to the BTCUSD ticker feed.
'  See https://docs.bitfinex.com/docs for more information.
Dim json1 As ChilkatJsonObject
json1.Initialize
json1.AppendString("event", "subscribe")
json1.AppendString("channel", "ticker")
json1.AppendString("pair", "BTCUSD")

Dim finalFrame As Boolean = True
success = ws.SendFrame(json1.Emit, finalFrame)

'  Subscribe to the ETHUSD ticker feed.
Dim json2 As ChilkatJsonObject
json2.Initialize
json2.AppendString("event", "subscribe")
json2.AppendString("channel", "ticker")
json2.AppendString("pair", "ETHUSD")

success = ws.SendFrame(json2.Emit, 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..
Dim receivedFinalFrame As Boolean = False
Dim numUpdatesReceived As Int = 0
Do While numUpdatesReceived < 7

    success = ws.ReadFrame
    If success <> True Then
        Log("Failed to receive a frame")
        Log("ReadFrame fail reason = " & ws.ReadFrameFailReason)
        Log(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 = ws.GetFrameData
        Log(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
    End If


Loop

'  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 = ws.SendClose(True, 1000, "Closing this websocket.")
If success <> True Then
    Log(ws.LastErrorText)
    Return
End If


'  Read the Close response.
success = ws.ReadFrame
If success <> True Then
    Log("ReadFrame fail reason = " & ws.ReadFrameFailReason)
    Log(ws.LastErrorText)
    Return
End If


Log("Success.")