CkPython

WebSocket Send/Receive Binary Data

See more WebSocket Examples

Demonstrates how to send and receive binary data on a websocket. This example uses Chilkat's websocket test echo server at ws://websockets.chilkat.io/wsChilkatEcho.ashx

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.

CkPython

import sys
import chilkat

success = False

# 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 sends a small JPG file (about 7KB) in a websocket frame.
jpgData = chilkat.CkBinData()
success = jpgData.LoadFile("qa_data/jpg/starfish.jpg")

print("Number of bytes to send = " + str(jpgData.get_NumBytes()))

# Send a frame containing the JPG image data.
# This will be the first and final frame, and therefore this constitutes the entire message.
finalFrame = True
success = ws.SendFrameBd(jpgData,finalFrame)
if (success != True):
    print(ws.lastErrorText())
    sys.exit()

# Read the echoed binary frame(s).
# (We sent the JPG file in a single frame, but we may receive the echo in multiple frames, but it will be one message.)
# Read an incoming frames until we receive the final frame.
receivedFinalFrame = False
while receivedFinalFrame == False :

    # The ws object is accumulating the received data internally.  Once we get the final frame, we'll get the 
    # accumulated data which should constitute the entire JPG.
    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))

# Get the accumulated received data.
jpgReceivedData = chilkat.CkBinData()
ws.GetFrameDataBd(jpgReceivedData)
print("Received " + str(jpgReceivedData.get_NumBytes()) + " bytes")

# Save the received JPG to a file so we can check it..
jpgReceivedData.WriteFile("qa_output/starfish_ws.jpg")

# 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.")