(CkPython) Send and Receive WebSocket Messages

This example how to send and receive websocket messages.

A WebSocket message can be composed of one or more frames. The simple case is where a single frame is both the first and last frame in a message. This is the case where the 1st frame in the message has the "final frame" bit set.

This example demonstrates sending and receiving multi-frame messages.

Note: The websockets.chilkat.io server imposes the following limitations:
Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.

Chilkat Python Downloads install with pip pip3 install chilkat or download... Python Module for Windows, MacOS, Linux, Alpine Linux, Solaris

import sys
import chilkat

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

ws = chilkat.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.

rest = chilkat.CkRest()
# Connect to websockets.chilkat.io
# IMPORTANT: websockets.chilkat.io accepts frames of up to 16K in size and echoes them back.
# IMPORTANT: The websockets.chilkat.io server imposes the following limitations: 
# ---------- Messages must be 16K or less, and each connection is limited to a max of 16 echoed messages.
success = rest.Connect("websockets.chilkat.io",80,False,False)
ws.UseConnection(rest)
ws.AddClientHeaders()
responseBodyIgnored = rest.fullRequestNoBody("GET","/wsChilkatEcho.ashx")
success = ws.ValidateServerHandshake()
if (success != True):
    print(ws.lastErrorText())
    sys.exit()

# This example demonstrates sending and receiving a multi-frame message.

# The websocket message will be composed of three text lines, each frame will contain a single line.

# Send the 1st frame in the message.
finalFrame = False
success = ws.SendFrame("This is the 1st frame\r\n",finalFrame)
if (success != True):
    print(ws.lastErrorText())
    sys.exit()

# Send the 2nd frame in the message.
success = ws.SendFrame("This is the 2nd frame\r\n",finalFrame)
if (success != True):
    print(ws.lastErrorText())
    sys.exit()

# Send the 3rd and final frame in the message.
finalFrame = True
success = ws.SendFrame("This is the 3rd frame\r\n",finalFrame)
if (success != True):
    print(ws.lastErrorText())
    sys.exit()

# Read an incoming frames until we receive the final frame.
# Note: It may be that the echo server (websockets.chilkat.io) responds with 
# the full message in a single final frame.
receivedFinalFrame = False
while receivedFinalFrame == False :

    success = ws.ReadFrame()
    if (success != True):
        print("Failed to receive a frame")
        print("ReadFrame fail reason = " + str(ws.get_ReadFrameFailReason()))
        print(ws.lastErrorText())
        sys.exit()

    receivedFinalFrame = ws.get_FinalFrame()

    # Show the opcode and final frame bit for the frame just received:
    print("Frame opcode: " + ws.frameOpcode())
    print("Final frame: " + str(receivedFinalFrame))

# Return the message accumulated in the above calls to ReadFrame.
receivedMsg = ws.getFrameData()
print("Received: " + receivedMsg)

# Close the websocket connection.
success = ws.SendClose(True,1000,"Closing this websocket.")
if (success != True):
    print(ws.lastErrorText())
    sys.exit()

# Read the Close response.
success = ws.ReadFrame()
if (success != True):
    print("ReadFrame fail reason = " + str(ws.get_ReadFrameFailReason()))
    print(ws.lastErrorText())
    sys.exit()

# Should receive the "Close" opcode.
print("Received opcode: " + ws.frameOpcode())
# Should be the same status code we sent (1000)
print("Received close status code: " + str(ws.get_CloseStatusCode()))
# The server may echo the close reason.  If not, this will be empty.
print("Echoed close reason: " + ws.closeReason())

print("Success.")