Trying to create a web-front end for a Python3 backed application. The application will require bi-directional streaming which sounded like a good opportunity to look into websockets.
My first inclination was to use something already existing, and the example applications from mod-pywebsocket have proved valuable. Unfortunately their API doesn't appear to easily lend itself to extension, and it is Python2.
Looking around the blogosphere many people have written their own websocket server for earlier versions of the websocket protocol, most don't implement the security key hash so dont' work.
Reading RFC 6455 I decided to take a stab at it myself and came up with the following:
#!/usr/bin/env python3
"""
A partial implementation of RFC 6455
http://tools.ietf.org/pdf/rfc6455.pdf
Brian Thorne 2012
"""
import socket
import threading
import time
import base64
import hashlib
def calculate_websocket_hash(key):
magic_websocket_string = b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
result_string = key + magic_websocket_string
sha1_digest = hashlib.sha1(result_string).digest()
response_data = base64.encodestring(sha1_digest)
response_string = response_data.decode('utf8')
return response_string
def is_bit_set(int_type, offset):
mask = 1 << offset
return not 0 == (int_type & mask)
def set_bit(int_type, offset):
return int_type | (1 << offset)
def bytes_to_int(data):
# note big-endian is the standard network byte order
return int.from_bytes(data, byteorder='big')
def pack(data):
"""pack bytes for sending to client"""
frame_head = bytearray(2)
# set final fragment
frame_head[0] = set_bit(frame_head[0], 7)
# set opcode 1 = text
frame_head[0] = set_bit(frame_head[0], 0)
# payload length
assert len(data) < 126, "haven't implemented that yet"
frame_head[1] = len(data)
# add data
frame = frame_head + data.encode('utf-8')
print(list(hex(b) for b in frame))
return frame
def receive(s):
"""receive data from client"""
# read the first two bytes
frame_head = s.recv(2)
# very first bit indicates if this is the final fragment
print("final fragment: ", is_bit_set(frame_head[0], 7))
# bits 4-7 are the opcode (0x01 -> text)
print("opcode: ", frame_head[0] & 0x0f)
# mask bit, from client will ALWAYS be 1
assert is_bit_set(frame_head[1], 7)
# length of payload
# 7 bits, or 7 bits + 16 bits, or 7 bits + 64 bits
payload_length = frame_head[1] & 0x7F
if payload_length == 126:
raw = s.recv(2)
payload_length = bytes_to_int(raw)
elif payload_length == 127:
raw = s.recv(8)
payload_length = bytes_to_int(raw)
print('Payload is {} bytes'.format(payload_length))
"""masking key
All frames sent from the client to the server are masked by a
32-bit nounce value that is contained within the frame
"""
masking_key = s.recv(4)
print("mask: ", masking_key, bytes_to_int(masking_key))
# finally get the payload data:
masked_data_in = s.recv(payload_length)
data = bytearray(payload_length)
# The ith byte is the XOR of byte i of the data with
# masking_key[i % 4]
for i, b in enumerate(masked_data_in):
data[i] = b ^ masking_key[i%4]
return data
def handle(s):
client_request = s.recv(4096)
# get to the key
for line in client_request.splitlines():
if b'Sec-WebSocket-Key:' in line:
key = line.split(b': ')[1]
break
response_string = calculate_websocket_hash(key)
header = '''HTTP/1.1 101 Switching Protocols\r
Upgrade: websocket\r
Connection: Upgrade\r
Sec-WebSocket-Accept: {}\r
\r
'''.format(response_string)
s.send(header.encode())
# this works
print(receive(s))
# this doesn't
s.send(pack('Hello'))
s.close()
s = socket.socket( socket.AF_INET, socket.SOCK_STREAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(('', 9876))
s.listen(1)
while True:
t,_ = s.accept()
threading.Thread(target=handle, args = (t,)).start()
Using this basic test page (which works with mod-pywebsocket):
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Web Socket Example</title>
<meta charset="UTF-8">
</head>
<body>
<div id="serveroutput"></div>
<form id="form">
<input type="text" value="Hello World!" id="msg" />
<input type="submit" value="Send" onclick="sendMsg()" />
</form>
<script>
var form = document.getElementById('form');
var msg = document.getElementById('msg');
var output = document.getElementById('serveroutput');
var s = new WebSocket("ws://"+window.location.hostname+":9876");
s.onopen = function(e) {
console.log("opened");
out('Connected.');
}
s.onclose = function(e) {
console.log("closed");
out('Connection closed.');
}
s.onmessage = function(e) {
console.log("got: " + e.data);
out(e.data);
}
form.onsubmit = function(e) {
e.preventDefault();
msg.value = '';
window.scrollTop = window.scrollHeight;
}
function sendMsg() {
s.send(msg.value);
}
function out(text) {
var el = document.createElement('p');
el.innerHTML = text;
output.appendChild(el);
}
msg.focus();
</script>
</body>
</html>
This receives data and demasks it correctly, but I can't get the transmit path to work.
As a test to write "Hello" to the socket, the program above calculates the bytes to be written to the socket as:
['0x81', '0x5', '0x48', '0x65', '0x6c', '0x6c', '0x6f']
Which match the hex values given in section 5.7 of the RFC. Unfortunately the frame never shows up in Chrome's Developer Tools.
Any idea what I'm missing? Or a currently working Python3 websocket example?
When I try talking to your python code from Safari 6.0.1 on Lion I get
Unexpected LF in Value at ...
in the Javascript console. I also get an IndexError exception from the Python code.
When I talk to your python code from Chrome Version 24.0.1290.1 dev on Lion I don't get any Javascript errors. In your javascript the onopen() and onclose() methods are called, but not the onmessage(). The python code doesn't throw any exceptions and appears to have receive message and sent it's response, i.e exactly the behavior your seeing.
Since Safari didn't like the trailing LF in your header I tried removing it, i.e
header = '''HTTP/1.1 101 Switching Protocols\r
Upgrade: websocket\r
Connection: Upgrade\r
Sec-WebSocket-Accept: {}\r
'''.format(response_string)
When I make this change Chrome is able to see your response message i.e
got: Hello
shows up in the javascript console.
Safari still doesn't work. Now it raise's a different issue when I attempt to send a message.
websocket.html:36 INVALID_STATE_ERR: DOM Exception 11: An attempt was made to use an object that is not, or is no longer, usable.
None of the javascript websocket event handlers ever fire and I'm still seeing the IndexError exception from python.
In conclusion. Your Python code wasn't working with Chrome because of an extra LF in your header response. There's still something else going on because the code the works with Chrome doesn't work with Safari.
Update
I've worked out the underlying issue and now have the example working in Safari and Chrome.
base64.encodestring() always adds a trailing \n to it's return. This is the source of the LF that Safari was complaining about.
call .strip() on the return value of calculate_websocket_hash and using your original header template works correctly on Safari and Chrome.
Related
So, im trying to make a webserver and processing data with a pico in parallel, my goal is to reach the pico from my browser using the local network ip to see in what step the pico is working and what data is on the current loop, however i have two issues and i have no idea how to make it work:
When running the two process in parallel using _thread, the webserver function hangs until the dataprocess function finish, so i cant see in realtime what is going on, the webserver respond only when the other process is finished and it hangs again, i need to press f5 on my browser at the exact time when the dataprocess function finish and start again only to see part of the process because it hangs if i refresh my browser to see the progress
When running the webserver, the urequets.get function of the dataprocess function does not work, it throws [Errno 103] ECONNABORTED
Here is the part of my code that is not working:
import utime, machine, urequests, json, network, socket, _thread
led = machine.Pin("LED", machine.Pin.OUT)
def connect():
global wlan
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect("SSID", "PASSS")
while wlan.isconnected() == False:
print("Connecting...")
led.off()
utime.sleep_ms(100)
led.on()
utime.sleep_ms(100)
led.off()
utime.sleep_ms(100)
led.on()
utime.sleep_ms(100)
led.on()
ip = wlan.ifconfig()[0]
print(f'Connected on {ip}')
return ip
def open_socket(ip):
address = (ip, 80)
connection = socket.socket()
connection.bind(address)
connection.listen(1)
return connection
def webpage(steps):
html = f"""
<!DOCTYPE html>
<html>
<head>
<title>Pico 2</title>
</head>
<body>
<p>{steps}</p>
</body>
</html>
"""
return str(html)
def pushgetdata():
while wlan.isconnected() == True:
try:
global steps
led.off()
utime.sleep_ms(300)
led.on()
steps = "Step 1: Reading values from sensor one...<br>"
#function to read data from one sensor here
#...
#...
#...
led.off()
utime.sleep_ms(100)
led.on()
steps = steps + "Step 2: Reading values from sensor two...<br>"
#function to read data from other sensor here
#...
#...
#...
led.off()
utime.sleep_ms(100)
led.on()
steps = steps + "Step 3: Pushing and getting results...<br>"
jsondata = urequests.get("https://xxx.xxx.xxx/api/?device=pico2&sensor1=valulesfromsensor1&sensor2=valuesfromsensor2")
proceseddata = jsondata.json()
steps = steps + proceseddata + "<br>"
steps = steps + "Step 4: Doing things with results...<br>"
#function to do conditions and things with results...
#...
#...
#...
jsondata.close()
steps = steps + "Step 5: Finished, sleeping for the next round...<br>"
utime.sleep_ms(100)
led.off()
utime.sleep_ms(100)
led.on()
utime.sleep(900)
except OSError as e:
steps = steps + e
def serve(connection):
while True:
try:
client, addr = connection.accept()
print('client connected from', addr)
request = client.recv(1024)
request = str(request)
html = webpage(steps)
client.send('HTTP/1.0 200 OK\r\nContent-type: text/html\r\n\r\n')
client.send(html)
client.close()
except OSError as e:
client.close()
def webserver():
ip = connect()
connection = open_socket(ip)
_thread.start_new_thread(serve,(connection,))
try:
webserver()
pushgetdata()
except KeyboardInterrupt:
machine.reset()
I'm not sure exactly what's going on with your code, but using the same threading idea, please find here my solution for a similar problem I've encountered today if it helps.
from machine import Pin
from time import sleep
import wlan_data, network
import socket, _thread
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
wlan.connect(wlan_data.SSID, wlan_data.PASSWORD)
print("WLAN is connected: " + str(wlan.isconnected()))
page = open("index.html", "r")
html = page.read()
page.close()
sta_if = network.WLAN(network.STA_IF)
print(sta_if.ifconfig()[0])
def setUpSocket():
addr = socket.getaddrinfo('0.0.0.0', 80)[0][-1]
s = socket.socket()
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(addr)
s.listen(1)
return s
def serve(s):
while True:
try:
cl, addr = s.accept()
cl_file = cl.makefile('rwb', 0)
while True:
line = cl_file.readline()
if not line or line == b'\r\n':
break
response = html
cl.send('HTTP/1.0 200 OK\r\nContent-type: text/html\r\n\r\n')
cl.send(response)
cl.close()
except OSError as e:
cl.close()
def webserver():
s = setUpSocket()
_thread.start_new_thread(serve,(s,))
webserver()
led = machine.Pin("LED", machine.Pin.OUT)
led.toggle()
while 1:
led.toggle()
sleep(10)
_thread library is experimental and buggy. From the micropython documentation https://docs.micropython.org/en/latest/library/_thread.html
This module is highly experimental and its API is not yet fully settled and not yet described in this documentation.
From my own testing, some of the functionality works for a while, then you might add another import and things stop working. Best to steer clear until it is no longer an experimental feature.
I am trying to add a procedure to pop-up a modal dialog inside a plug-in.
Its purpose is to query a response at designated steps within the control-flow of the plug-in (not just acquire parameters at its start).
I have tried using gtk - I get a dialog but it is asynchronous - the plugin continues execution. It needs to operate as a synchronous function.
I have tried registering a plugin in order to take advantage of the gimpfu start-up dialogue for same. By itself, it works; it shows up in the procedural db when queried. But I never seem to be able to actually invoke it from within another plug-in - its either an execution error or wrong number of arguments no matter how many permutations I try.
[Reason behind all of this nonsense: I have written a lot of extension Python scripts for PaintShopPro. I have written a App package (with App.Do, App.Constants, Environment and the like that lets me begin to port those scripts to GIMP -- yes it is perverse, and yes sometimes the code just has to be rewritten, but for a lot of what I actual use in the PSP.API it is sufficient.
However, debugging and writing the module rhymes with witch. So. I am trying to add emulation of psp's "SetExecutionMode" (ie interactive). If
set, the intended behavior is that the App.Do() method will "pause" after/before it runs the applicable psp emulation code by popping up a simple message dialog.]
A simple modal dialogue within a gimp python-fu plug-in can be implemented via gtk's Dialog interface, specifically gtk.MessageDialog.
A generic dialog can be created via
queryDialogue = gtk.MessageDialog(None, gtk.DIALOG_DESTROY_WITH_PARENT \
gtk.MESSAGE_QUESTION, \
gtk.BUTTONS_OK_CANCEL, "")
Once the dialog has been shown,
a synchronous response may be obtained from it
queryDialogue.show()
response = queryDialogue.run()
queryDialogue.hide()
The above assumes that the dialog is not created and thence destroyed after each use.
In the use case (mentioned in the question) of a modal dialog to manage single stepping through a pspScript in gimp via an App emulator package, the dialogue message contents need to be customized for each use. [Hence, the "" for the message argument in the Constructor. [more below]]
In addition, the emulator must be able to accept a [cancel] response to 'get out of Dodge' - ie quit the entire plug-in (gracefully). I could not find a gimpfu interface for the latter, (and do not want to kill the app entirely via gimp.exit()). Hence, this is accomplished by raising a custom Exception class [appTerminate] within the App pkg and catching the exception in the outer-most scope of the plugin. When caught, then, the plug-in returns (exits).[App.Do() can not return a value to indicate continue/exit/etc, because the pspScripts are to be included verbatim.]
The following is an abbreviated skeleton of the solution -
a plug-in incorporating (in part) a pspScript
the App.py pkg supplying the environment and App.Do() to support the pspScript
a Map.py pkg supporting how pspScripts use dot-notation for parameters
App.py demonstrates creation, customization and use of a modal dialog - App.doContinue() displays the dialogue illustrating how it can be customized on each use.
App._parse() parses the pspScript (excerpt showing how it determines to start/stop single-step via the dialogue)
App._exec() implements the pspScript commands (excerpt showing how it creates the dialogue, identifies the message widget for later customization, and starts/stops its use)
# App.py (abbreviated)
#
import gimp
import gtk
import Map # see https://stackoverflow.com/questions/2352181/how-to- use-a-dot-to-access-members-of-dictionary
from Map import *
pdb = gimp.pdb
isDialogueAvailable = False
queryDialogue = None
queryMessage = None
Environment = Map({'executionMode' : 1 })
_AutoActionMode = Map({'Match' : 0})
_ExecutionMode = Map({'Default' : 0}, Silent=1, Interactive=2)
Constants = Map({'AutoActionMode' : _AutoActionMode}, ExecutionMode=_ExecutionMode ) # etc...
class appTerminate(Exception): pass
def Do(eNvironment, procedureName, options = {}):
global appTerminate
img = gimp.image_list()[0]
lyr = pdb.gimp_image_get_active_layer(img)
parsed = _parse(img, lyr, procedureName, options)
if eNvironment.executionMode == Constants.ExecutionMode.Interactive:
resp = doContinue(procedureName, parsed.detail)
if resp == -5: # OK
print procedureName # log to stdout
if parsed.valid:
if parsed.isvalid:
_exec(img, lyr, procedureName, options, parsed, eNvironment)
else:
print "invalid args"
else:
print "invalid procedure"
elif resp == -6: # CANCEL
raise appTerminate, "script cancelled"
pass # terminate plugin
else:
print procedureName + " skipped"
pass # skip execution, continue
else:
_exec(img, lyr, procedureName, options, parsed, eNvironment)
return
def doContinue(procedureName, details):
global queryMessage, querySkip, queryDialogue
# - customize the dialog -
if details == "":
msg = "About to execute procedure \n "+procedureName+ "\n\nContinue?"
else:
msg = "About to execute procedure \n "+procedureName+ "\n\nDetails - \n" + details +"\n\nContinue?"
queryMessage.set_text(msg)
queryDialogue.show()
resp = queryDialogue.run() # get modal response
queryDialogue.hide()
return resp
def _parse(img, lyr, procedureName, options):
# validate and interpret App.Do options' semantics vz gimp
if procedureName == "Selection":
isValid=True
# ...
# parsed = Map({'valid' : True}, isvalid=True, start=Start, width=Width, height=Height, channelOP=ChannelOP ...
# /Selection
# ...
elif procedureName == "SetExecutionMode":
generalOptions = options['GeneralSettings']
newMode = generalOptions['ExecutionMode']
if newMode == Constants.ExecutionMode.Interactive:
msg = "set mode interactive/single-step"
else:
msg = "set mode silent/run"
parsed = Map({'valid' : True}, isvalid=True, detail=msg, mode=newMode)
# /SetExecutionMode
else:
parsed = Map({'valid' : False})
return parsed
def _exec(img, lyr, procedureName, options, o, eNvironment):
global isDialogueAvailable, queryMessage, queryDialogue
#
try:
# -------------------------------------------------------------------------------------------------------------------
if procedureName == "Selection":
# pdb.gimp_rect_select(img, o.start[0], o.start[1], o.width, o.height, o.channelOP, ...
# /Selection
# ...
elif procedureName == "SetExecutionMode":
generalOptions = options['GeneralSettings']
eNvironment.executionMode = generalOptions['ExecutionMode']
if eNvironment.executionMode == Constants.ExecutionMode.Interactive:
if isDialogueAvailable:
queryDialogue.destroy() # then clean-up and refresh
isDialogueAvailable = True
queryDialogue = gtk.MessageDialog(None, gtk.DIALOG_DESTROY_WITH_PARENT, gtk.MESSAGE_QUESTION, gtk.BUTTONS_OK_CANCEL, "")
queryDialogue.set_title("psp/APP.Do Emulator")
queryDialogue.set_size_request(450, 180)
aqdContent = queryDialogue.children()[0]
aqdHeader = aqdContent.children()[0]
aqdMsgBox = aqdHeader.children()[1]
aqdMessage = aqdMsgBox.children()[0]
queryMessage = aqdMessage
else:
if isDialogueAvailable:
queryDialogue.destroy()
isDialogueAvailable = False
# /SetExecutionMode
else: # should not get here (should have been screened by parse)
raise AssertionError, "unimplemented PSP procedure: " + procedureName
except:
raise AssertionError, "App.Do("+procedureName+") generated an exception:\n" + sys.exc_info()
return
A skeleton of the plug-in itself. This illustrates incorporating a pspScript which includes a request for single-step/interactive execution mode, and thus the dialogues. It catches the terminate exception raised via the dialogue, and then terminates.
def generateWebImageSet(dasImage, dasLayer, title, mode):
try:
img = dasImage.duplicate()
# ...
bkg = img.layers[-1]
frameWidth = 52
start = bkg.offsets
end = (start[0]+bkg.width, start[1]+frameWidth)
# pspScript: (snippet included verbatim)
# SetExecutionMode / begin interactive single-step through pspScript
App.Do( Environment, 'SetExecutionMode', {
'GeneralSettings': {
'ExecutionMode': App.Constants.ExecutionMode.Interactive
}
})
# Selection
App.Do( Environment, 'Selection', {
'General' : {
'Mode' : 'Replace',
'Antialias' : False,
'Feather' : 0
},
'Start': start,
'End': end
})
# Promote
App.Do( Environment, 'SelectPromote' )
# und_so_weiter ...
except App.appTerminate:
raise AssertionError, "script cancelled"
# /generateWebImageSet
# _generateFloatingCanvasSetWeb.register -----------------------------------------
#
def generateFloatingCanvasSetWeb(dasImage, dasLayer, title):
mode="FCSW"
generateWebImageSet(dasImage, dasLayer, title, mode)
register(
"generateFloatingCanvasSetWeb",
"Generate Floating- Frame GW Canvas Image Set for Web Page",
"Generate Floating- Frame GW Canvas Image Set for Web Page",
"C G",
"C G",
"2019",
"<Image>/Image/Generate Web Imagesets/Floating-Frame Gallery-Wrapped Canvas Imageset...",
"*",
[
( PF_STRING, "title", "title", "")
],
[],
generateFloatingCanvasSetWeb)
main()
I realize that this may seem like a lot of work just to be able to include some pspScripts in a gimp plug-in, and to be able to single-step through the emulation. But we are talking about maybe 10K lines of scripts (and multiple scripts).
However, if any of this helps anyone else with dialogues inside plug-ins, etc., so much the better.
I want to built a function that sends a request from ModBus to serial in hex. I more o less have a working function but have two issues.
Issue 1
[b'\x06', b'\x1c', b'\x00!', b'\r', b'\x1e', b'\x1d\xd3', b'\r', b'\n', b'\x1e', b'\x1d']
I cant remove this part b'\r', b'\n', using the .split('\r \n') method since It's not a string.
Issue 2
When getting a value from holding register 40 (33) and i try to use the .to_bytes() method I keep getting b'\x00!', b'\r' and I'm expecting b'\x21'
r = client.read_holding_registers(40)
re = r.registers[0]
req = re.to_bytes(2, 'big')
My functions to generate my request and to send trough pyserial.
def scanned_code():
code = client.read_holding_registers(0)
# code2= client.re
r = code.registers[0]
return r
def send_request(data):
""" Takes input from create_request() and sends data to serial port"""
try:
for i in range(data):
serial_client.write(data[i])
# serial_client.writelines(data[i])
except:
print('no se pudo enviar el paquete <<<--------------------')
def create_request(job):
""" Request type is 33 looks for job
[06]
[1c]
req=33[0d][0a]
job=30925[0d][0a][1e]
[1d]
"""
r = client.read_holding_registers(40)
re = r.registers[0]
req = re.to_bytes(2, 'big')
num = job.to_bytes(2, 'big')
data = [
b'\x06',
b'\x1C',
req,
b'\x0D',
b'\x1E',
num,
b'\x0D',
b'\x0A',
b'\x1E',
b'\x1D'
]
print(data)
while True:
# verify order_trigger() is True.
while order_trigger() != False:
print('inside while loop')
# set flag coil back to 0
reset_trigger()
# get Job no.
job = scanned_code()
# check for JOB No. dif. than 0
if job != 0:
print(scanned_code())
send_request(create_request(job))
# send job request to host to get job data
# send_request()
# if TRUE send job request by serial to DVI client
# get job request data
# translate job request data to modbus
# send data to plc
else:
print(' no scanned code')
break
time.sleep(INTERNAL_SLEEP_TIME)
print('outside loop')
time.sleep(EXTERNAL_SLEEP_TIME)
As an additional question is this the proper way of doing things?
I met an error when running codes at the bottom. It's like a simple ftp.
I use python2.6.6 and CentOS release 6.8
In most linux server, it gets right results like this:(I'm very sorry that I have just sign up and couldn't )
Clinet:
[root#Test ftp]# python client.py
path:put|/home/aaa.txt
Server:
[root#Test ftp]# python server.py
connected...
pre_data:put|aaa.txt|4
cmd: put
file_name: aaa.txt
file_size: 4
upload successed.
But I get errors in some server(such as my own VM in my PC). I have done lots of tests(python2.6/python2.7, Centos6.5/Centos6.7) and found this error is not because them. Here is the error imformation:
[root#Lewis-VM ftp]# python server.py
connected...
pre_data:put|aaa.txt|7sdfsdf ###Here gets the wrong result, "sdfsdf" is the content of /home/aaa.txt and it shouldn't be sent here to 'file_size' and so it cause the "ValueError" below
cmd: put
file_name: aaa.txt
file_size: 7sdfsdf
----------------------------------------
Exception happened during processing of request from ('127.0.0.1', 10699)
Traceback (most recent call last):
File "/usr/lib64/python2.6/SocketServer.py", line 570, in process_request_thread
self.finish_request(request, client_address)
File "/usr/lib64/python2.6/SocketServer.py", line 332, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "/usr/lib64/python2.6/SocketServer.py", line 627, in __init__
self.handle()
File "server.py", line 30, in handle
if int(file_size)>recv_size:
ValueError: invalid literal for int() with base 10: '7sdfsdf\n'
What's more, I found that if I insert a time.sleep(1) between sk.send(cmd+"|"+file_name+'|'+str(file_size)) and sk.send(data) in client.py, the error will disappear. I have said that I did tests in different system and python versions and the error is not because them. So I guess that is it because of some system configs? I have check about socket.send() and socket.recv() in python.org but fount nothing helpful. So could somebody help me to explain why this happend?
The code are here:
#!/usr/bin/env python
#coding:utf-8
################
#This is server#
################
import SocketServer
import os
class MyServer(SocketServer.BaseRequestHandler):
def handle(self):
base_path = '/home/ftp/file'
conn = self.request
print 'connected...'
while True:
#####receive pre_data: we should get data like 'put|/home/aaa|7'
pre_data = conn.recv(1024)
print 'pre_data:' + pre_data
cmd,file_name,file_size = pre_data.split('|')
print 'cmd: ' + cmd
print 'file_name: '+ file_name
print 'file_size: '+ file_size
recv_size = 0
file_dir = os.path.join(base_path,file_name)
f = file(file_dir,'wb')
Flag = True
####receive 1024bytes each time
while Flag:
if int(file_size)>recv_size:
data = conn.recv(1024)
recv_size+=len(data)
else:
recv_size = 0
Flag = False
continue
f.write(data)
print 'upload successed.'
f.close()
instance = SocketServer.ThreadingTCPServer(('127.0.0.1',9999),MyServer)
instance.serve_forever()
#!/usr/bin/env python
#coding:utf-8
################
#This is client#
################
import socket
import sys
import os
ip_port = ('127.0.0.1',9999)
sk = socket.socket()
sk.connect(ip_port)
while True:
input = raw_input('path:')
#####we should input like 'put|/home/aaa.txt'
cmd,path = input.split('|')
file_name = os.path.basename(path)
file_size=os.stat(path).st_size
sk.send(cmd+"|"+file_name+'|'+str(file_size))
send_size = 0
f= file(path,'rb')
Flag = True
#####read 1024 bytes and send it to server each time
while Flag:
if send_size + 1024 >file_size:
data = f.read(file_size-send_size)
Flag = False
else:
data = f.read(1024)
send_size+=1024
sk.send(data)
f.close()
sk.close()
The TCP is a stream of data. That is the problem. TCP do not need to keep message boundaries. So when a client calls something like
connection.send("0123456789")
connection.send("ABCDEFGHIJ")
then a naive server like
while True;
data = conn.recv(1024)
print data + "_"
may print any of:
0123456789_ABCDEFGHIJ_
0123456789ABCDEFGHIJ_
0_1_2_3_4_5_6_7_8_9_A_B_C_D_E_F_G_H_I_J_
The server has no chance to recognize how many sends client called because the TCP stack at client side just inserted data to a stream and the server must be able to process the data received in different number of buffers than the client used.
Your server must contain a logic to separate the header and the data. All of application protocols based on TCP use a mechanism to identify application level boundaries. For example HTTP separates headers and body by an empty line and it informs about the body length in a separate header.
Your program works correctly when server receives a header with the command, name and size in a separate buffer it it fails when client is fast enough and push the data into stream quickly and the server reads header and data in one chunk.
I am working on a project, to control a RC car with Raspberry Pi and have done it with he help of WeiOPi.
Now I wanted to add a Ultrasonic Range Finder on it (I have HC-SR04).
I googled in internet about it and didn't find much information, I have a question.
How I can combine the python code with java-script and html to print the Distance on the web page.
Thanks in advance,
Any Help will be appreciated.
Regards,
H.M
P.S, I am only 13 and new to Programming.
EDIT:
Unfinished Code:
The python code is:
import webiopi
import RPi.GPIO as GPIO
import time
GPIO.setmode(GPIO.BCM)
TRIG = 23
ECHO = 24
print "Distance Measurement In Progress"
GPIO.setup(TRIG,GPIO.OUT)
GPIO.setup(ECHO,GPIO.IN)
GPIO.output(TRIG, False)
print "Waiting For Sensor To Settle"
time.sleep(2)
GPIO.output(TRIG, True)
time.sleep(0.00001)
GPIO.output(TRIG, False)
while GPIO.input(ECHO)==0:
pulse_start = time.time()
while GPIO.input(ECHO)==1:
pulse_end = time.time()
pulse_duration = pulse_end - pulse_start
distance = pulse_duration * 17150
# _____________________________________________________________________
# I want to print the following string (distance) to print on html page
# ---------------------------------------------------------------------
#webiopi.macro
def getSensor(channel):
percent = round(distance, 2)
return "%.2f%%" % percent
#Instantiate the server on the port 8000, it starts immediately in its own thread
server = webiopi.Server(port=8000)
# Run our loop until CTRL-C is pressed or SIGTERM received
webiopi.runLoop()
# -------------------------------------------------- #
# Termination part #
# -------------------------------------------------- #
# Stop the server
server.stop()
The html code:
<script type="text/javascript" src="/webiopi.js"></script>
<script type="text/javascript">
webiopi().ready(init);
// defines function passed previously to webiopi().ready()
function init() {
// automatically refresh UI each seconds
setInterval(updateUI, 1000);
}
// function called through setInterval
function updateUI() {
webiopi().callMacro("getSensor", 0, sensorCallback);
webiopi().callMacro("getSensor", 1, sensorCallback);
webiopi().callMacro("getSensor", 2, sensorCallback);
webiopi().callMacro("getSensor", 3, sensorCallback);
}
// callback function used to display sensor data
function sensorCallback(macroName, channel, data) {
// use jQuery to change spans content
$("#sensor"+channel).text(data);
}
</script>
</head>
<body>
<div align="center">
<div>Sensor 0: <span id="sensor0"></span></div>
<div>Sensor 1: <span id="sensor1"></span></div>
<div>Sensor 2: <span id="sensor2"></span></div>
<div>Sensor 3: <span id="sensor3"></span></div>
</div>
</body>
</html>