Send/Receive messages at the same time socket python

Question

I have been working on a simple python socket chat room where the client and server can send messages to each other. The issue that I came across was that the server and client can only send one message at a time. I want it to work like any other chat room, where I could receive a message when I am sending a message, any help will help greatly

Server.py

import socket
import sys

s = socket.socket()
host = socket.gethostname()
print(" server will start on host : ", host)
port = 8080
s.bind((host,port))
name = input(str("Please enter your username: "))
print("")
print("Server is waiting for incoming connections")
print("")
s.listen(1)
conn, addr = s.accept()
print("Recieved connection")
print("")
s_name = conn.recv(1024)
s_name = s_name.decode()
print(s_name, "has joined the chat room")
conn.send(name.encode())

while 1:
    message = input(str("Please enter your message: "))
    conn.send(message.encode())
    print("Sent")
    print("")
    message = conn.recv(1024)
    message = message.decode()
    print(s_name, ":" ,message)
    print("")

Client.py

import socket
import sys

s = socket.socket()
host = input(str("Please enter the hostname of the server : "))
port = 8080
s.connect((host,port))
name = input(str("Please enter your username : "))
print(" Connected to chat server")

s.send(name.encode())
s_name = s.recv(1024)
s_name = s_name.decode()
print("")
print(s_name, "has joined the chat room ")

while 1:
    message = s.recv(1024)
    message = message.decode()
    print(s_name, ":" ,message)
    print("")
    message = input(str("Please enter your message: "))
    message = message.encode()
    s.send(message)
    print("Sent")
    print("")

and once again, wrong use of tcp sockets. you cannot use messages this way. — Daniel, Feb 10 '19 at 21:03
protocol are rules, that define messages. Some tutorial: https://realpython.com/python-sockets/ — Daniel, Feb 10 '19 at 21:20

Armali · Accepted Answer · 2019-02-15T07:57:33.673

CaSper has given me the server code where multiple clients can connect to the server but the problem now is that the clients can not talk to each other …

That's primarily because your client wants s_name = s.recv(1024), while CaSper's server doesn't send its name. Here's a variant of your client (expecting host and port as command arguments) which works with CaSper's server and also addresses your original issue (client can only send one message at a time) by using separate threads:

import socket
import sys

s = socket.socket()
s.connect((sys.argv[1], int(sys.argv[2])))
name = input(str("Please enter your username : "))
print(" Connected to chat server")
s.send(name.encode())

def receive_and_print():
    for message in iter(lambda: s.recv(1024).decode(), ''):
        print(":", message)
        print("")
import threading
background_thread = threading.Thread(target=receive_and_print)
background_thread.daemon = True
background_thread.start()

while 1:
    s.send(input("Please enter your message: ").encode())
    print("Sent")
    print("")

Note that CaSper's server has a series of deficiencies:

Even now that your clients can send messages at any time, the server waits for a message from one by one client, i. e. when it waits for client A, client B can send a message, but the server receives and broadcasts it only after client A has sent something.
It doesn't handle client disconnects.
It goes into a busy loop when all clients disconnected.

For a better server example, see the question Handle multiple requests with select.

… could you possibly change my server so that it works …

Here's a variant of your server which works with this client, also using separate threads for input and reception:

import socket
import sys

s = socket.socket()
host = socket.gethostname()
print(" server will start on host : ", host)
port = 8080
s.bind((host,port))
name = input(str("Please enter your username: "))
print("")
print("Server is waiting for incoming connections")
print("")
s.listen(1)
conn, addr = s.accept()
print("Recieved connection")
print("")
s_name = conn.recv(1024)
s_name = s_name.decode()
print(s_name, "has joined the chat room")

def input_and_send():
    while 1:
        message = name+" : "+input(str("Please enter your message: "))
        conn.send(message.encode())
        print("Sent")
        print("")
import threading
background_thread = threading.Thread(target=input_and_send)
background_thread.daemon = True
background_thread.start()

for message in iter(lambda: conn.recv(1024).decode(), ''):
    print(s_name, ":", message)
    print("")

@system123456 - Which server do you mean - yours, CaSper's, or the one in the linked question? — Armali, Feb 13 '19 at 06:42
When I use your client code that you gave and CaSper server code It still won't let me send messages to other clients — Hass786123, Feb 13 '19 at 19:42
@system123456 - When I use them, it will. Did you start the clients with the right hostname and port of the server? Did you take the mentioned deficiencies into account? This means e. g. that other clients may have to send a message before one client's message is received and broadcasted. Of course I do not recommend using CaSper's server. — Armali, Feb 14 '19 at 09:36
Using CaSper's server might be causing this problem so could you possibly change my server so that it works please — Hass786123, Feb 14 '19 at 16:33
@system123456 - I added the changed server to the answer. Changes are only after the `print(s_name, "has joined the chat room")`. — Armali, Feb 15 '19 at 07:57
What would I add so that more than one client can connect and how would i make it so that when the server sends a message to the client it gets sent striaght away without the client typing a message first? — Hass786123, Feb 15 '19 at 15:42
@system123456 - Which server do you mean? The server variant in this answer **already** _sends a message to the client it gets sent striaght away without the client typing a message first_. — Armali, Feb 18 '19 at 06:48

score 0 · Answer 2 · answered Feb 10 '19 at 21:14

0

Did you try to used Threading module or time module maybe.This happen because both scripts send messages in same time.Try Ex(Client wait message from server frist, then client sent message to server).

answered Feb 10 '19 at 21:14

CaSper

1
2

I have looked at it but I just don't know how to implement it into my code is it possible for you to show me how to? – Hass786123 Feb 10 '19 at 21:19
When I run the server and run the clients the server sayes that they have connected but how do I make it so that the clients can talk together? – Hass786123 Feb 11 '19 at 20:21

score -2 · Answer 3 · edited Feb 13 '19 at 21:23

THIS IS SERVER

import socket
import threading as th

def accept_client():
    while True:
        # ACCEPTING    
        cli_sock, cli_add = ser_sock.accept()
        uname = cli_sock.recv(1024)
        CONN_LIST.append((uname, cli_sock))
        print('%s is now connected' %uname)

def broadcast_usr():
    while True:
        for i in range(len(CONN_LIST)):
            try:
                data = CONN_LIST[i][1].recv(1024)
                if data:
                    b_usr(CONN_LIST[i][1], CONN_LIST[i][0], data)
            except Exception as x:
                print(x.message)
                break

def b_usr(cs_sock, sen_name, msg):
    for i in range(len(CONNECTION_LIST)):
        if (CONN_LIST[i][1] != cs_sock):
            CONN_LIST[i][1].send(sen_name)
            CONN_LIST[i][1].send(msg)


if __name__ == "__main__":    
    CONN_LIST = []

    # SOCKET
    ser_sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

    # BINDING
    host = '192.168.x.x' #LOCAL HOST
    port = 4444
    ser_sock.bind((host, port))

    # LISTENING    
    ser_sock.listen(1)
    print('Chat server started on port : ' + str(port))

    thread_ac = th.Thread(target = accept_client)
    thread_ac.start()

    thread_bs = th.Thread(target = broadcast_usr)
    thread_bs.start()

`… in b_usr for i in range(len(CONNECTION_LIST)): NameError: global name 'CONNECTION_LIST' is not defined ` — Armali, Feb 12 '19 at 08:36

Send/Receive messages at the same time socket python

Server.py

Client.py

3 Answers3

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