(Tcl) Read Bitfinex WebSocket Ticker Channel

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

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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 public ticker feed.
# See https://docs.bitfinex.com/docs for more information.
set json [new_CkJsonObject]

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

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

# Read the response.
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 $json
    exit
}

# Examine the response
# We should get this:
# {"event":"subscribed","channel":"ticker","chanId":2751,"pair":"BTCUSD"}
puts [CkWebSocket_getFrameData $ws]

# Begin reading the ticker feed.
# We'll just read the 1st 5 updates and then exit..
set receivedFinalFrame 0
set numUpdatesReceived 0
while {$numUpdatesReceived < 5} {

    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 $json
        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]
        set numUpdatesReceived [expr $numUpdatesReceived + 1]
    }

}

# 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 $json
    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 $json
    exit
}

puts "Success."

delete_CkWebSocket $ws
delete_CkRest $rest
delete_CkJsonObject $json