(Tcl) WebSocket Connect

Demonstrates how to establish a WebSocket connection. Once the connection is established, messages may be sent back-and-forth. Messages are sent in frames, where the last frame in the message is indicated by a "final" bit. A frame constitutes the entire message if the first frame sent has the "final" bit sent. (In most cases, you'll probably be sending single-frame messages.)

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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.

# --------------------------------------------------
# A WebSocket connection begins life as an HTTP GET request containing a few special header fields,
# such as "Upgrade: websocket".   

# Your application will use the Chilkat Rest class to send the initial HTTP GET.  This allows you
# to use the full capability of the Chilkat Rest class to customize the GET for any particular situation.
# For example:
# 
#   - If custom HTTP request header fields must be added.
#   - If authentication is required, such as OAuth2, OAuth1, Basic HTTP Auth, etc.
#   - If HTTPS, SSH Tunneling, Proxies (HTTP or SOCKS), or other advanced connection or TLS features are required.
# 

set rest [new_CkRest]

set success [CkRest_Connect $rest "someserver.com" 80 0 0]
if {$success != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    exit
}

set ws [new_CkWebSocket]

# Tell the WebSocket to use this connection.
set success [CkWebSocket_UseConnection $ws $rest]
if {$success != 1} then {
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkRest $rest
    delete_CkWebSocket $ws
    exit
}

# Add the standard WebSocket open handshake headers that will be needed.
# (This adds the required HTTP request headers to the rest object.)
CkWebSocket_AddClientHeaders $ws

# Add any additional headers that might be desired.
# Two common WebSocketSpecific headers are "Sec-WebSocket-Protocol" and "Origin".
CkRest_AddHeader $rest "Sec-WebSocket-Protocol" "x-something"
CkRest_AddHeader $rest "Origin" "http://someserver.com"

# Do the open handshake.
set responseBody [CkRest_fullRequestNoBody $rest "GET" "/something"]
if {[CkRest_get_LastMethodSuccess $rest] != 1} then {
    puts [CkRest_lastErrorText $rest]
    delete_CkRest $rest
    delete_CkWebSocket $ws
    exit
}

# If successful, the HTTP response status code should be 101,
# and the response body will be empty. (If it failed, we'll have a look
# at the response body..)
set statusCode [CkRest_get_ResponseStatusCode $rest]
puts "Response status code: $statusCode"

if {$statusCode != 101} then {
    puts "$responseBody"
    puts "-- Failed because of unexpected response status code."
    delete_CkRest $rest
    delete_CkWebSocket $ws
    exit
}

# We have the expected 101 response, so let's now validate the 
# contents of the response, such as the value sent by the server in the
# Sec-WebSocket-Accept header. 
set success [CkWebSocket_ValidateServerHandshake $ws]
if {$success != 1} then {
    puts [CkWebSocket_lastErrorText $ws]
    delete_CkRest $rest
    delete_CkWebSocket $ws
    exit
}

puts "WebSocket connection successful."

# The application may now begin sending and receiving frames on the WebSocket connection.
# (At this point, we're done with the rest object...)

delete_CkRest $rest
delete_CkWebSocket $ws