(Tcl) 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 Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

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

set ws [new_CkWebSocket]

# 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.

set rest [new_CkRest]

# Connect to api.bitfinex.com
set success [CkRest_Connect $rest "api.bitfinex.com" 443 1 0]
CkWebSocket_UseConnection $ws $rest
CkWebSocket_AddClientHeaders $ws

set responseBody [CkRest_fullRequestNoBody $rest "GET" "/ws"]
set success [CkWebSocket_ValidateServerHandshake $ws]
if {$success != 1} then {
    puts [CkWebSocket_lastErrorText $ws]
    puts "$responseBody"
    puts [CkRest_responseHeader $rest]
    delete_CkWebSocket $ws
    delete_CkRest $rest
    exit
}

# After connecting, the bitfinex websocket server will send
# an info message that contains the actual version of the websocket stream.
# Receive that message..
set success [CkWebSocket_ReadFrame $ws]
if {$success != 1} then {
    puts "Failed to receive a frame"
    puts "ReadFrame fail reason = [CkWebSocket_get_ReadFrameFailReason $ws]"
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkWebSocket $ws
    delete_CkRest $rest
    exit
}

# We should get this:
# {"event":"info","version":1.1,"platform":{"status":1}}
puts [CkWebSocket_getFrameData $ws]

# Subscribe to the BTCUSD ticker feed.
# See https://docs.bitfinex.com/docs for more information.
set json1 [new_CkJsonObject]

CkJsonObject_AppendString $json1 "event" "subscribe"
CkJsonObject_AppendString $json1 "channel" "ticker"
CkJsonObject_AppendString $json1 "pair" "BTCUSD"

set finalFrame 1
set success [CkWebSocket_SendFrame $ws [CkJsonObject_emit $json1] $finalFrame]

# Subscribe to the ETHUSD ticker feed.
set json2 [new_CkJsonObject]

CkJsonObject_AppendString $json2 "event" "subscribe"
CkJsonObject_AppendString $json2 "channel" "ticker"
CkJsonObject_AppendString $json2 "pair" "ETHUSD"

set success [CkWebSocket_SendFrame $ws [CkJsonObject_emit $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..
set receivedFinalFrame 0
set numUpdatesReceived 0
while {$numUpdatesReceived < 7} {

    set success [CkWebSocket_ReadFrame $ws]
    if {$success != 1} then {
        puts "Failed to receive a frame"
        puts "ReadFrame fail reason = [CkWebSocket_get_ReadFrameFailReason $ws]"
        puts [CkWebSocket_lastErrorText $ws]
        delete_CkWebSocket $ws
        delete_CkRest $rest
        delete_CkJsonObject $json1
        delete_CkJsonObject $json2
        exit
    }

    # The responses we desire are in Text frames, where the opcode = 1.
    if {[CkWebSocket_get_FrameOpcodeInt $ws] == 1} then {
        set receivedText [CkWebSocket_getFrameData $ws]
        puts "$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"}
        set numUpdatesReceived [expr $numUpdatesReceived + 1]
    }

}

# 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.
set success [CkWebSocket_SendClose $ws 1 1000 "Closing this websocket."]
if {$success != 1} then {
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkWebSocket $ws
    delete_CkRest $rest
    delete_CkJsonObject $json1
    delete_CkJsonObject $json2
    exit
}

# Read the Close response.
set success [CkWebSocket_ReadFrame $ws]
if {$success != 1} then {
    puts "ReadFrame fail reason = [CkWebSocket_get_ReadFrameFailReason $ws]"
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkWebSocket $ws
    delete_CkRest $rest
    delete_CkJsonObject $json1
    delete_CkJsonObject $json2
    exit
}

puts "Success."

delete_CkWebSocket $ws
delete_CkRest $rest
delete_CkJsonObject $json1
delete_CkJsonObject $json2