I have a scenario where I need to first respond with HTTP 200 to a server request (due to a time limit) and then continue processing with the actual work.
I also can not use threads, processes, tasks, queues or any other method that would allow me to do this by starting a parallel "process".
My approach is to use the build in "Simple HTTP" server and I am looking for a way to force the server to respond with HTTP 200 and then be able to continue processing.
The current code will receive a POST request and print its content after a 3 seconds. I put a placeholder where I would like to send the response.
from http.server import BaseHTTPRequestHandler, HTTPServer
import time
class MyWebServer(BaseHTTPRequestHandler):
def do_POST(self):
content_length = int(self.headers['Content-Length'])
post_data = self.rfile.read(content_length)
self.send_response_only(200)
self.end_headers()
# force server to send request ???
time.sleep(3)
print(post_data)
def run(server_class=HTTPServer, handler_class=MyWebServer, port=8000):
server_address = ('', port)
httpd = server_class(server_address, handler_class)
print('Starting httpd...')
httpd.serve_forever()
if __name__ == "__main__":
run()
I figured out a workaround solution. You can force the server to send a 200 OK and continue processing after with these two commands:
self.finish()
self.connection.close()
This solution is from this SO question: SimpleHTTPRequestHandler close connection before returning from do_POST method
However, this will apparently close the internal IO buffer that the server uses and it won't be able to server any additional requests after that.
To avoid running into an exception it works to terminate the program (which works for me). However this is just a workaround and I would still be looking for a solution that allows the server to keep processing new requests.
from http.server import BaseHTTPRequestHandler, HTTPServer
import time
class MyHandler(BaseHTTPRequestHandler):
def do_POST(self):
content_length = int(self.headers['Content-Length'])
post_data = self.rfile.read(content_length)
self.send_response_only(200)
self.end_headers()
self.finish()
self.connection.close()
time.sleep(3)
print(post_data)
quit()
def run(server_class=HTTPServer, handler_class=MyHandler, port=8000):
server_address = ('', port)
httpd = server_class(server_address, handler_class)
print('Starting httpd...')
httpd.serve_forever()
if __name__ == "__main__":
run()
Related
Can anyone tell me what's the solution for this?
When I run it and load it from the browser... It's only loading and never displaying the "Hello Word!" text.
But the text will appear in the browser after I shutdown the server by triggering the KeyboardInterrupt.
PS: SSL is enabled in python 2.6 interpreter on Linux. Also, it's not working in Windows 7.
Here's the code:
#!/usr/bin/python
from BaseHTTPServer import BaseHTTPRequestHandler,HTTPServer
import ssl
import sys
PORT_NUMBER = int(sys.argv[1])
#This class will handles any incoming request from the browser
class myHandler(BaseHTTPRequestHandler):
#Handler for the GET requests
def do_GET(self):
print(self.requestline)
#print(self.rfile.read(content_length))
self.send_response(200)
self.send_header('Content-type','text/html')
self.end_headers()
# Send the html message
self.wfile.write("Hello World !".encode())
return
try:
#Create a web server and define the handler to manage the
#incoming request
server = HTTPServer(('', PORT_NUMBER), myHandler)
server.socket = ssl.wrap_socket(server.socket, certfile='cert.pem',keyfile='key.pem', server_side=True)
print 'Started httpserver on port ' , PORT_NUMBER
#Wait forever for incoming htto requests
server.serve_forever()
except KeyboardInterrupt:
print '^C received, shutting down the web server'
server.socket.close()
in order to run this in Python 2.x, command: python this_code.py [port]
Example:
python this_code.py 8080
Then navigate to the browser with the address: https://localhost:8080/
If I remove this line, it'll work but it's just running under HTTP protocol and not in HTTPS (which I'm intended to run in):
server.socket = ssl.wrap_socket(server.socket, certfile='cert.pem',keyfile='key.pem', server_side=True)
I use http webserver python script:
class PiFaceWebHandler(http.server.BaseHTTPRequestHandler):
def do_GET(self):
[....]
if __name__ == "__main__":
# get the port
if len(sys.argv) > 1:
port = int(sys.argv[1])
else:
port = DEFAULT_PORT
# set up PiFace Digital
PiFaceWebHandler.pifacedigital = pifacedigitalio.PiFaceDigital()
print("Starting simple PiFace web control at:\n\n"
"\thttp://{addr}:{port}\n\n"
"Change the output_port with:\n\n"
"\thttp://{addr}:{port}?output_port=0xAA\n"
.format(addr=get_my_ip(), port=port))
# run the server
server_address = ('', port)
try:
httpd = http.server.HTTPServer(server_address, PiFaceWebHandler)
httpd.serve_forever()
except KeyboardInterrupt:
print('^C received, shutting down server')
httpd.socket.close()
It's working fine, but i want the script (or another one, ) check some I/O continuously, in a while loop, ie.
And sometimes this I/O could change state with http request.
Currently, I/O changes state on http request, but i don't find the tips to change them on external trigger (another input ie).
How can i do? Where can i code the loop test?
do I make myself clear?
Thanks,
I've written a code in tornado that connects to a server that is pushing an infinite data stream, processes the data stream and sends it out on a websocket server.
The problem is that the way I implemented it the server became blocked on a particular function and doesn't accept any more clients since it never exits the function serving the data to the websocket. I want the connection to the server and the data retrieved from it processed only once but send the processed data to all the clients that connect to my tornado server. Could someone please help me, I can't figure out a way to do it. Here's my code with processing of data removed:
import socket
import ssl
import tornado.httpserver
import tornado.websocket
import tornado.ioloop
import tornado.web
websockets = []
class WSHandler(tornado.websocket.WebSocketHandler):
def readData(self):
while True:
line = self.ssl_sock.read()
#PROCESS THE READ LINE AND CONVERT INTO RESULTING DATA
if(toSend):
self.write_message(result)
def makeConnection(self):
self.ssl_sock.connect(self.address)
self.readData()
def open(self):
print 'New connection was opened'
self.s=socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.ssl_sock=ssl.wrap_socket(self.s, cert_reqs=ssl.CERT_NONE)
self.address=('SERVER_ADDRESS',5000)
self.nodes=[]
self.edges=[]
if self not in websockets:
print ('added')
websockets.append(self)
if(len(websockets)==1):
print('executing make conn')
self.makeConnection()
else:
self.readData()
print('executing read data')
def on_message(self, message):
print 'Incoming message:', message
self.write_message("You said: " + message)
def on_close(self):
print 'Connection was closed...'
application = tornado.web.Application([
(r'/ws', WSHandler),
])
if __name__ == "__main__":
http_server = tornado.httpserver.HTTPServer(application)
http_server.listen(8888)
tornado.ioloop.IOLoop.instance().start()
Tornado is an asynchronous framework, that is, all your IO must be run within its event loop, otherwise the whole server gets stuck.
Try having a look at Tornado Async Client.
I'd like to be able to respond to a GET by immediately returning a message and then starting a process to run in the background and finish a task. This works fine with BaseHTTPServer.HTTPServer and extending BaseHTTPRequestHandler. However, when I follow the instructions here to add SSL to the server, the response isn't sent until the subprocess finishes. Assuming that Firefox is displaying what it receives as it receives it, and double-checking with Firebug, it looks like nothing at all is sent until the subprocess completes. I tested in Chrome and saw the same result. Code below; I'm at a loss for how to continue debugging.
class SecureHTTPServer(HTTPServer):
def __init__(self, server_address, HandlerClass):
BaseServer.__init__(self, server_address, HandlerClass)
ctx = SSL.Context(SSL.SSLv3_METHOD)
ctx.use_privatekey_file(SSL_CERT)
ctx.use_certificate_file(SSL_CERT)
self.socket = SSL.Connection(ctx, socket.socket(self.address_family, self.socket_type))
self.server_bind()
self.server_activate()
def shutdown_request(self, request):
request.shutdown()
class RecordingHandler(BaseHTTPRequestHandler):
def setup(self):
self.connection = self.request
self.rfile = socket._fileobject(self.request, "rb", self.rbufsize)
self.wfile = socket._fileobject(self.request, "wb", self.wbufsize)
def do_GET(self):
key = 'abc'
p = Process(target = some_func, args = (key,))
# Some_func takes ~15 seconds to complete, and it logs its progress so that it's clear that the response is only sent after some_func is complete.
p.daemon = True
p.start()
self.send_response(200)
self.end_headers()
self.wfile.write('recording key ' + key)
def run():
try:
server = SecureHTTPServer(('', 8080), RecordingHandler)
print 'Waiting for input on port 8080.'
server.serve_forever()
except KeyboardInterrupt:
print 'Received keyboard interrupt, exiting.'
server.shutdown()
Apparently I just needed to give up, restart, and try googling things again. I found this solution:
import BaseHTTPServer, SimpleHTTPServer
import ssl
httpd = BaseHTTPServer.HTTPServer(('localhost', 4443), SimpleHTTPServer.SimpleHTTPRequestHandler)
httpd.socket = ssl.wrap_socket (httpd.socket, certfile='path/to/localhost.pem', server_side=True)
httpd.serve_forever()
I still have no idea what was wrong with the previous setup, but this works just fine.
Code:
from socket import *
sP = 14000
servSock = socket(AF_INET,SOCK_STREAM)
servSock.bind(('',sP))
servSock.listen(1)
while 1:
connSock, addr = servSock.accept()
connSock.send('HTTP/1.0 200 OK\nContent-Type:text/html\nConnection:close\n<html>...</html>')
connSock.close()
When I go to the browser and type in localhost:14000, I get an error 101- ERR_CONNECTION_RESET The connection was reset? Not sure why! What am I doing wrong
Several bugs, some more severe than others ... as #IanWetherbee already noted, you need an empty line before the body. You also should send \r\n not just \n. You should use sendall to avoid short sends. Last, you need to close the connection once you're done sending.
Here's a slightly modified version of the above:
from socket import *
sP = 14000
servSock = socket(AF_INET,SOCK_STREAM)
servSock.bind(('',sP))
servSock.listen(1)
while 1:
connSock, addr = servSock.accept()
connSock.sendall('HTTP/1.0 200 OK\r\nContent-Type:text/html\r\nConnection:close\r\n\r\n<html><head>foo</head></html>\r\n')
connSock.close()
Running your code, I have similar errors and am unsure on their origins too. However, rather than rolling your own HTTP server, have you considered a built in one? Check out the sample below. This can also support POST as well (have to add the do_POST method).
Simple HTTP Server
from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
class customHTTPServer(BaseHTTPRequestHandler):
def do_GET(self):
self.send_response(200)
self.send_header('Content-type', 'text/html')
self.end_headers()
self.wfile.write('<HTML><body>Hello World!</body></HTML>')
return
def main():
try:
server = HTTPServer(('',14000),customHTTPServer)
print 'server started at port 14000'
server.serve_forever()
except KeyboardInterrupt:
server.socket.close()
if __name__=='__main__':
main()