Nrthugu

I am creating a socket client and trying to obtain some data. In order to do so, I need to connect to a web server via socket and the server actually creates another socket which listens and awaits for the data after which sends back to the client.

The problem I have with the code below is that my socket client does not wait for the incoming data from the server and just accepts empty data.

How can I wait for a non-empty data from the server using Python sockets?

My code:

import sys

import json

import socketIO_client

import time



host = 'https://SOME_URL'



socketIO = socketIO_client.SocketIO(host, params={"email" : "edmund@gmail.com"})

def on_connect(*args):

    print "socket.io connected"



def on_disconnect(*args):

    print "socketIO diconnected"



socketIO.on('connect', on_connect)

socketIO.on('disconnect', on_disconnect)



def on_response_state(*args):

    print args # Prints ()



socketIO.emit('receive_state',on_response_state)

socketIO.wait_for_callbacks(seconds=3)

Here's an example using socket. Using s.accept(), the client will wait till a client accepts the connection before starting the while loop to receive data. This should help with your problem.

def receiver():

    PORT = 123

    CHUNK_SIZE = 1024



    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

    s.bind(('0.0.0.0', PORT))

    s.listen(1)

    conn,address=s.accept()  # accept an incoming connection using accept() method which will block until a new client connects



    while True:

        datachunk = conn.recv(CHUNK_SIZE) # reads data chunk from the socket in batches using method recv() until it returns an empty string

        if not datachunk:

            break  # no more data coming in, so break out of the while loop

        data.append(datachunk)  # add chunk to your already collected data



    conn.close()

    print(data)

    return



receiver()

put the recv socket in a while thread.

like this:

  def rec(self):



    while 1:

        sleep 0.01

        rdata = self.clientsocket.recv(self.buffsize)



        print("rec from server: ", rdata.decode('utf8'),'n','press enter to continue')

....

t2 = threading.Thread(target=y.rec, name="rec") 



t2.start()

Since you're using the SocketIO library to include parameters (achieved using requests), and want to emit a message, you can wait indefinitely for a response by not specifying a wait time.

with SocketIO(host, params={"email" : "edmund@gmail.com"}) as socketIO:

    def on_response_state(*args):

        print args # Prints ()



    socketIO.emit('receive_state', on_response_state)

    socketIO.wait()